Industrial Rope Access Investigation Into Items Of Personal Protective Equipment
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AlBx0VH d f8 d6tRX2 p0 8Xd6 P hHP dDP8t8dAp0 8p0 d6tlB2 l0F dDPHxJp00h8tF dD P00 x JAhHPAl8Pp0 8J 2 x4 pBP 2 x4 pBP 2 x4 pBP 2 dP8tpF dP6X4p6F Bt6 tp xAhgD 3L nqpRlI0v0hH 0 RESEARCH REPORTAdam Long Malcolm Lyon and Graham LyonLyon Equipment LimitediiCrown copyright for reproduction should be made in writing toCopyright Unit Her Majestys Stationery OfficeSt Clements House 216 Colegate Norwich NR3 1BQFirst published 2001ISBN 0 7176 2091 3All rights reserved No part of this publication may bereproduced stored in a retrieval system or transmittedin any form or by any means electronic recording or permission of the copyright owneriii CONTENTS 1 PRINCIPLES1 11 INTRODUCTION1 12 AIMS OBJECTIVES AND SCOPE13 QUESTIONNAIRE3 14 TESTING3 2 ROPES7 21 INTRODUCTION7 22 ROPE TYPES7 23 ULTIMATE STATIC STRENGTH9 24 ROPES SUMMARY10 3 KNOTS11 31 INTRODUCTION11 32 METHODS11 33 RESULTS12 34 CONTAMINATED ROPE TESTS204 ANCHOR FORCES23 41 INTRODUCTION23 42 ABSEILING23 43 ASCENDING24 44 WORK POSITIONING25 45 WORKING26 46 RIGGING27 47 RAPIDLY28 48 SUMMARY28 5 ROPE PROTECTORS29 51 INTRODUCTION29 52 METHODS29 53 UNPROTECTED29 54 ROLL MODULE PETZL30 55 CANVAS SHEATH30 56 POLYVINYL CHLORIDE PVCATED FABRIC SHEATH30 57 COMPRESSED AIR FLEXIBLE HOSE PIPE31 58 CARPET31 59 PVC COATED FABRIC SCRAPS SIMULATED ROPE BAG32 510 ROPE PROTECTORS SUMMARY32 6 ROPE ADJUSTMENT DEVICES35 61 INTRODUCTION35 62 TYPE A BACKUP DEVICES35 63 TYPE B ASCENDER DEVICES64 TYPE C DESCENDER DEVICES637 ATTACHMENT LANYARDS COWS TAILS79 71 INTRODUCTION79 72 METHODS79 73 KNOTTED ROPE COWS TAILS874 PETZL JANE SEWN TERMINATION COWS TAILS81 75 KNOTTED TAPE COWS TAILS76 COWS TAILS SUMMARY81 8 LANYARDS FALL ARREST83 81 INTRODUCTION83 82 BEAL BEP ENERGY ABSORBER84 83 BH SALA85 84 CHARLET MOSER85 85 PAMMENTER PETRIE P P86 PETZL ABSORBICA87 87 PETZL ABSORBICA I87 88 MILLER DALLOZ88 89 SPANSET88 810 LANYARDS CONCLUSIONS89 9 PRUSIK KNOTS91 91 INTRODUCTION91 92 TESTS91 93 BACHMANN KNOT92 94 BLAKE KNOT93 95 FRENCH PRUSIK94 96 KLEIMHEIST KNOT95 97 PRUSIK KNOT96 98 SUMMARY96 10 CONCLUSIONS97 101 GENERAL CONCLUSIONS AND COMMENT97 11 FUTURE WORK99 12 APPENDICES101 121 APPENDIX 1 PERSONNEL INVOLVED IN THE PROJECT103 122 APPENDIX 2 QUESTIONNAIRE SUMMARY OF REPLIES105 123 APPENDIX 3 ROPE ABRASION111 124 APPENDIX 4 TEST MACHINES LOCATIONS AND METHODS113 125 APPENDIX 5 ABRASION TESTS RECORDED RESULTS121 126 APPENDIX 6 KNOTS STRENGTH TESTS129 127 APPENDIX 7 LANYARDS STATIC TESTS133 128 APPENDIX 8 TYPE A BACKUP DEVICES MINIMUM STATIC STRENGTH TEST135 129 APPENDIX 9 TYPE A BACKUP DEVICES DYNAMIC TESTS137 1210 APPENDIX 10 TYPE A BACKUP DEVICES MINIMUM WORKING STRENGTH141 1211 APPENDIX 11 TYPE B DEVICES ASCENDERS BODY TEST143 1212 APPENDIX 12 TYPE B DEVICES ASCENDERS DYNAMIC TESTS145 1213 APPENDIX 13 TYPE B DEVICES ASCENDERS MINIMUM WORK147 1214 APPENDIX 14 TYPE C DEVICES DESCENDERS STATIC TESTS149 1215 APPENDIX 15 TYPE C DEVICES DESCENDERS DYNAMIC TEST151 1216 APPENDIX 16 TYPE C DEVICES DESCENDERS WORKING STRENGTH153 1217 APPENDIX 17 LANYARD DYNAMIC TESTS155 1218 APPENDIX 18 PRUSIK KNOTS157 11 INTRODUCTION Developments in equipment and techniques for climbing and potholing during the 1970s led to new faster and lighter ways of moving around in vertical environments These sporting developments were adopted for use in the workplace after appropriate modifications and development of the techniques including the addition of extra safety measures This method of work became known as rope access Rope access has taken the last decade to become generally accepted as a valid way to work at height Initial reservations were fuelled by a perceived danger of workers dangling from insubstantial ropes and by the employment of cavers and climbers without specific industrial training Perhaps the now archaic French term for rope access travaux acrobatiques sums up these old perceptions The approach adopted by the United Kingdoms Industrial Rope Access Trade Association IRATA may be summed up as the integration of rigorous work procedures and operator training This coupled with a growing statistical record of safe work has led to a gradual reassessment of rope access in the workplace It enables workers undertaking temporary work to access difficult places quickly and relatively cheaply and to undertake inspections and a wide range of stabilising and other works Because this is a relatively new field of work there has been little coordinated research into the equipment employed which is presently governed largely by standards for fall arrest and for mountaineering equipment This research undertaken for the Health Safety Executive HSE is designed to shed light into the capabilities and limitations of some of the main components in the work system In addition to rope access the versatility of the new methods and equipment is influencing the techniques used by steeplejacks theatre riggers and others The results of this research will thus also have some relevance to work at height in general however it is performed A vital concept in understanding the equipment used in rope access is that of the safety chain whereby no one component is more important than the others in the system Like any work system the rope access work system must be inspected at regular intervals for weak links in the chain so that any problems can then be eliminated To make all the equipment used in work at height intrinsically foolproof would be to make work methods impractically slow cumbersome and expensive and would inhibit innovation and development As a result all the equipment is open to misuse making proper training vital With the right training work situations perceived to be potentially dangerous can be tackled with minimal risk A key feature of equipment for rope access is versatility Almost all rope adjustment devices will have secondary uses especially during rigging for rescues etc This reduces the amount of hardware an operative has to carry and increases their operational abilities and safety margin INDUSTRIAL ROPE ACCESS TRADE House235 Ash Road Aldershot Hampshire GU12 4DD 12 AIMS OBJECTIVES AND SCOPE 121 Aim The aim of the research was to examine the and behaviour of certain items of Personal Protective Equipment PPE122 Objectives The objective was to obtain knowledge of the performance of the equipment and to comment on ways that it might be improved 123 Scope The research covered equipment used in the following areas of work Rope access Work positioning Fall arrest Arboriculture 124 Equipment The following types of equipment were tested Backup devices Ascenders Descenders Lanyards fall arrest and cows tails Knots termination and prusik Anchorage loadings Rope protectors Equipment beyond this core section of the safety chain eg harnesses and helmetst covered Similarly the connectors eg karabiners and screw link connectors used as links within the chain were also beyond the remit of the project Although these areas were not investigated this does not imply there is no scope for work on them Anchorages themselves were not tested although the forces applied to them in a typical work situation were studied The criteria used in selecting equipment for test were as follows products currently in use Deduced by circulation of a questionnaire see Appendix 2 for a summary of the replies new or soon to be available products products available on the United Kingdom market and working on different principles to those in the two categories above 13 QUESTIONNAIRE A questionnaire was circulated to industrial users of rope access equipment This included and theatre riggers as well as rope access technicians The objective was to gain an insight into what equipment was being used in the workplace how it was being used and why Within rope access the techniques are fairly standard although variations exist In the worlds of arboriculture and theatre rigging however techniques are far more varied A summary of the replies is provided in the Appendix The summary includes both statistics and comments provided by the respondents The questionnaire was circulated primarily to rope access workers The comments are particularly useful as technicians often use equipment provided and chosen by their employers Hence data on what equipment is in use do not necessarily reflect user choice It was not possible to circulate the questionnaire more widely 14 TESTING 141 General A variety of tests was used to assess the performance of the equipment Where appropriate these were taken from either established or provisional standards However in some circumstances new tests had to be devised The aim was always to produce results that were both relevant and impartial ie the tests must not have been designed to favour a particular device 142 Criteria It was clearly important to test items of PPE against standards It also seemed prudent to roadtest them in the manner in which they would be used Items that produce impressive test results on paper may well prove to be impractical and ultimately unusable in a work situation This is due to a number of factors Firstly standards do not specify a method of use In order to produce comparable results all items were tested in the same manner irrespective of their recommended method of use Clearly this would not allow some items to perform as well as they might Therefore both the tests and the results had to be carefully assessed in accordance with the relevant method of use Secondly the ease of use of the item had to be considered Irrespective of test performance and methods of use a key measure of the value of a piece of equipment is its acceptability by the user the device will not be used if it is not userfriendly It is therefore inevitable that this aspect of the test programme was to some extent a product review from the users point of view While this type of test will always be less objective than scientific tests and preferences will always vary from person to person impartiality was of paramount importance and every attempt was made to limit subjectivity To give new products a chance against established favourites all devices were used by both IRATA level 3 and level 1 Rope Access Technicians While the level 3 Technicians expertise and experience were invaluable in such a test the level 1 Technician is likely to be less familiar with all the equipment and therefore hopefully less biased against unfamiliar equipment and will be more open to changeWhile in some circumstances the practical performance will outweigh the test results ideally items of equipment needed to excel in both practical and technical areas 143 Verification For the tests to be valid it was essential to make them reproducible allowing for verification of results either by the test team or by anyone with similar test facilities To achieve this all test setups were made to be as simple as possible Replicating tests usually 3 timeshlighted tests where variations were likely Where initial tests indicated that the results would not vary such replication was curtailed 144 Methods In the device testing programme the Provisional European Standard prEN2841 May 2000was used as the starting point for the test methods Results were not correlated directly to the requirements of what is at the time of writing a draft standard The concern was with relative performance rather than the simple pass or fail criteria of the draft standard Only tests that dealt directly with the function of the devices were attempted All the tests were performed on new equipment with no attempts made to replicate wear or contamination by mud dust etc Tests specified in prEN 12841 but beyond the scope of the project for example conditioning to oil were not attempted During the tests monitoring included not only the performance of the devices but also that of the test itself This allowed assessment of the suitability of the tests for the devices concerned During the test programme the rationale behind some of the specified test parameters from prEN 12841 was unclear Attempts were made in these cases to discover the original justifications behind them In the report therefore every attempt is made to explain the purpose of each test Additional tests were then designed to address areas not covered by prEN 12841 In most cases a document search revealed applicable tests in previous standards but in a few cases notably edge protection new tests had to be designed For a detailed description of test methods machines and locations see the Appendix 145 Limitations of results All tests suffer from attempts to standardise real situations Practical deployment of the types of equipment to be tested involves differing weights directions of loading combinations of items etc No two operatives are exactly the same size and weight and no two falls will load the equipment in exactly the same manner On the other hand the tests performed have to isolate the component in question be standardised and be repeatable In order to address this the aim was to examine only the worstcase scenario The unavoidable result of this is that the tests were by necessity harsh In addition worstcase scenarios often occur when equipment is subject to slight misuse The magnitude of this was carefully examined when designing the tests The level of misuse had to be conceivable during normal operation arising for example from carelessness or haste More serious levels of misuse could not be addressed since they become irrelevant in normal operation by trained personnel In some cases the final tests may represent morethan worstcase scenarios for example where all elasticity is taken out of a test but would always be present to dampen peak forces in a real situation Thus the results from these tests reflect the harshest of possible regimes In all cases results are presented in the report in an interpreted form Raw data is available in the Appendices However without an exhaustive understanding of the test methods and recording equipment used interpretation can be difficult BRITISH STANDARDS INSTITUTION BSI prEN 12841 May 2000 Personal protective equipment for prevention of falls from a height Rope Access Work positioning systems Rope adjustment devicesAll the results are strictly comparative ie good results and bad results relate only to better or worse performance when compared to other devices Bad results do not therefore necessarily mean a device is dangerous but that other devices will be more effective in a similar situation Where devices do perform in a manner that could prove dangerous this is clearly indicated Good test performance is only part of what makes a safe device If the device is not userfriendly experience has shown that it will not be used 6 21 INTRODUCTION Ropes are the primary element in a rope access system They are the highway along which the operative travels up down and even sideways They are the core of the progression and the safety systems They must be selected and used with care Ropes used for the suspension of persons require a significant degree of shockload absorbency In this respect rope technology has reached a plateau with no fundamental changes in the textiles or constructions used in the past two decades In fact just one polymer predominates polyamide Other materials may be used in particular circumstances polyester steel but only with special safeguards due to their lack of appropriate elasticity and ability to absorb energy It was beyond the scope of this project to conduct exhaustive tests of ropes in isolation Rope technology and standards are well developed and understood Rope representative of the types used in rope access was used in conjunction with all the rope adjustment devices and with knotted terminations The performance of the combination of rope and device together is of key importance 22 ROPE TYPES There are two standards relevant to ropes for use in climbing and the suspension of personnel Both are of kernmantel sheath and core constructions Figure 1 Kernmantel rope showing sheath and core construction of low stretch rope For most rope access purposes the appropriate Standard is BS EN 1891 BRITISH STANDARDS INSTITUTION BS EN 1891 1998Personal protective equipment for the prevention of falls from a height Low stretch kernmantel ropes This standard has two categories or types A and B Only type A ropes are recommended for work purposes Both types of rope have low extension during normal working procedures but they have sufficient stretch to dissipate the type of forces likely to be generated by the progression of operatives along them up to those generated by a fall from the anchor point This severity of fall where the distance travelled before arrest equals the length of rope arresting the fall is known as fall factor 1 The sheath on lowstretch ropes is generally thicker than that of dynamic ropes specifically to withstand the wear and tear of rope adjustment devices Type A ropes to BS EN 1891 can be from 10 mm to 16 mm in diameter However the industry norm is 105 mm and so three different ropes of this diameter were chosen for the tests Table 1 Details of the Type A low stretch ropes used in the tests Manufacturer Rope name Diameter mm nominalWeight gmm Static strength kN Sheathcore ratio Beal Antipodes 105 650 270 38 62 Edelrid Softstatic 105 670 299 41 59 Marlow Static 105 697 329 37 63 All figures are from manufacturers data sheets except where marked this was measured during the project All were soaked in tap water and dried conditioned before use according to the manufacturers instructions In certain applications where greater elasticity is required the appropriate rope will be a dynamic rope complying with BS EN 892 This standard specifies single half and twin ropes Only single dynamic rope is generally applicable to work purposes It should be deployed in circumstances where a fall greater than Factor 1 could be encountered in simple terms a fall from above the position of the anchor In practical terms this means where ropes are used for lead climbing or to make cows tails a type of attachment lanyard or link Single dynamic ropes on the market vary in diameter from 94 mm to 11 mm A rope at the upper end of this size range is recommended for work use The following table shows the rope which was chosen as being reasonably representative of this type of rope Table 2 Details of dynamic rope used during the tests Manufacturer name Diameter mm nominalWeight gmm Impact force FF2 80 kg masskN Sheathcore ratio Beal Apollo 11 78 74 30 70 All figures are manufacturers stated except where marked measured during the project FF2 means fall factor 2BRITISH STANDARDS INSTITUTION BS EN 892 1997 Mountaineering equipment Dynamic mountaineering ropes Safety requirements and test methods The ropes are all fundamentally of the same construction Parameters that vary slightly between manufacturers include sheath thickness expressed as a percentage of the total rope mass tightness of the sheath the tightness of the sheath on to the core and core construction These combine to give the rope its feel and character To create dynamic rope similar original fibres are used but they are heattreated before construction of the rope This makes them retract shrink and become more elastic giving them better ability to absorb dynamic shock loads Different uses require ropes of different constructions for heavyduty use eg in arboriculture a thicker sheath may be required to counter the high levels of abrasion All the tests except on prusik knotsrried out with new unused ropes which were conditioned before testing The behaviour of ropes may be expected to change during their lifetime Investigation of the performance of used ropes will require further research During the test programme attempts were made to investigate the effect that various environmental factors have on rope strength One sample of ropes was subjected to weathering one to rust and one to both weathering and bird droppings Ideally these ropes should then have had the worst sections subjected to an ultimate static strength test However due to the difficulty of achieving this see section 23he ropes were tested as short lanyards consisting of two overhand knots A full description of the method is included under the heading of Knots see Chapter 3s the method was then identical for the termination knots the results could be directly compared 23 ULTIMATE STATIC STRENGTH By using Beals static test rig in Vienne France it was possible to test ropes to their ultimate static breaking strength Obtaining the ultimate static strength of a low stretch rope requires a special arrangement for gripping the ends of the rope Each end of the rope is wrapped around a capstan before being fixed in a clamp In this way the load in the rope at the clamp is reduced and slippage at the clamps is avoided Due to time restraints only a small number of samples were tested however these were sufficient to gain a representative result The aim was to test both new samples of rope and some that had been damaged during the dynamic tests The ropes that had been used in the dynamic tests on the Petzl Microcender rope adjustment device were chosen as they showed localised damage to the sheath which appeared to be severe By placing the damaged section between the test capstans it was possible to ascertain whether the damage affected the ultimate strength of the rope Two initial tests carried out on new Edelrid 105 mm rope gave peak forces of 284 kN and 289 kN A sample that had suffered light glazing showed no decrease in strength while the sample that had been damaged in the Microcender tests showed a very slight strength decrease breaking at 27 kN Tests on a section of Beal 105 mm showed a lower strength of 245 kN In the final test a piece of lightly glazed Marlow 105 mm rope was tested which gave a high peak force of 31 kN As all these figures are higher than even the strongest knot it is reasonable to assume that even heavy glazing will not cause weakening of the rope to a point where it becomes dangerous These figures may be compared to the manufacturers stated breaking strengths given in Table 1 Table 3 Ultimate strngth of low stretch ropes Manufacturer Diameter mm kN Condition of rope all low stretch Edelrid 105 284 289 New unused Edelrid 105 280 300 Light glazing Edelrid 105 270 Nominal damage Microcender dynamic test Beal 105 245 Nominal damage Microcender dynamic test Marlow 105 310 Light glazing 24 ROPES SUMMARY Throughout the device testing programme clear differences were observed between the low stretch ropes The Edelrid rope was the supplest and the most slick while the Marlow rope was much stiffer Devices on the latter tended to slip less In dynamic tests on Type A and Type C rope adjustment devices the greatest slippage was seen on Edelrid the least on Marlow and with intermediate slippage on Beal These differences can be explained by differences in manufacture The main difference is that Edelrid ropes are in effect dry treated during their manufacture although they are not marketed as such This treatment reduces the effect of the conditioning that was given to all the ropes before testing This is reflected in the manufacturers figures for shrinkage in water Edelrid 23 Beal 4 Marlow 32 When the ropes are soaked the sheath shrinks and tightens around the core resulting in a stiffer rope In the case of the Edelrid rope this does not occur to the same extent and the rope remains supple allowing easier slippage of devices It can be surmised that slippage is likely to decrease with use although this remains to be tested As only one dynamic rope was used in the test programme comparative testing was not possible The main use was to test the strength and abilities of knots The other use was to test the performance of backup devices if used on such a rope 31 INTRODUCTION Termination knots enable a termination to be made at any point along the ropes length Most create loops which are then used to attach the rope to anchors Exceptions are firstly ropeconnecting knots which do just that The double fishermans was the only knot of this type tested Secondly hitching knots for hitching to a post The post can be anything from a tree trunk to the 10 mm bar of a karabiner Again only one knot of this type was tested the clove hitch Different knots are used in different situations The tests produced ultimate force strength figures for each knot By comparing these figures to the ultimate breaking force of the rope itself a percentage figure can also be presented for the strength of the knot Slight variations above and below a knots average strength are inevitable These may or may not be related to how the knot is tied In a simple knot such as a bowline it is difficult to see any difference between one knot and another whereas in a figureofeight subtle differences can be identified These are largely due to slight twists imparted as the rope is tied These may even be present in a well dressed knot A knots strength depends largely on the radius of the first bend as the loaded end of the rope enters the knot A very tight bend will result in a weaker knot than one with a more gradual In the more complex knots several parameters can be altered within the internal geometry of the knot by tying them slightly differently Preliminary tests were carried out to identify how these variations affect strength In the main tests these variations were considered see section 32 Methods paragraph 3 32 METHODS The knots were tested by making up a short lanyard with approximately 200 mm length of rope between two near identical knots at each end This was then pretensioned on the test rig to a force of 2 kN It was then left to relax for a minimum of thirty minutes No standard exists for testing knots the standard for slings BS EN 566 1997 specifies an extension rate of 500 mm per minute This rate was used to test the knots The lanyard was then tested to destruction and the maximum force sustained was recorded This was repeated three times for each knot and rope combination to illustrate the potential for varying strengths and to reduce the risk of inaccuracies Where knots are complex enough to allow slight permutations this setup enables them to be tested against each other to find the weakest By using the strongest permutation at both ends the maximum possible strength for the knot can be found and viceversa for the weakest As each test consisted of three samples a representative crosssection of results could then be produced for each knot BRITISH STANDARDS INSTITUTION BS EN 5661997 Mountaineering equipment Slings Safety requirements and test methods 33 RESULTS The main body of results is presented in graphical form as both absolute and percentage figures see Figures 12 13Numerical results can be found in the Appendix The principal conclusion of the tests is that there is no cause for concern over knots No knot was found to reduce rope strength to less than 55 of its absolute strength with the majority being considerably stronger While one knots average strength may be greater than that of anothers there is considerable variation between individual test values For example it cannot be guaranteed that a figureofnine knot will always be stronger than an overhand knot Larger variations are generally due to the permutations mentioned above in the simpler knots the reasons are less obvious 331 Double overhand knot Figure 2 Double overhand knot This is the simplest knot that forms a secure loop in the rope It is very easy to tie but very difficult to undo after loading In all cases failure occurs in the same place where the loaded rope first rounds the loop Whether it rounds the loop above or below the loose end can affect strength by up to 10 In the overhand knot it is stronger if the working rope lies above the rope end In the tests overhand knots retained between 58 and 68 of the rope full strength 332 Double figureofeight knot Figure 3 Double figureofeight knot Adding an extra halfturn to a double overhand knot creates a double figureofeight knot a very common knot in both rope access and mountaineering It is both stronger and easier to undo than the doubleoverhand knot while still being of fairly low bulk First bend of ropeUnlike the double overhand and double figureofnine knots the rope positions in the first bend do not appear to have a marked effect on diminution of strength In the tests the double figureofeight knot retained between 66 and 77 of the ropes full strength 333 Double figureofnine knot Figure 4 Double figureofnine knot Another halfturn to the double figureofeight creates the double figureofnine It is slightly stronger again and even easier to undo Again it is very common in rope access particularly for securing to anchors where ease of undoing is more important than bulk Unlike the double overhand it is stronger if the loaded end lies underneath the loose end in the knot In the tests it had the widest range of test values of all the knots tested with values ranging from 68 to 84 of the ropes full strength 334 Double figureoften knot Figure 5 Double figureoften knot Adding another halfturn to a double figureofnine making two full turns in total creates this very bulky knot Although it is slightly stronger than a double figureofnine its bulk and the amount of rope needed to tie it mean that it is not commonly used in either industry or sport As with the double figureofnine it is stronger if the loaded end lies below the loose end in the knot It produced only one test value higher than the figureofnine but averages were higher with variations from 73 to 87 335 Double figureofeight on the bight Figure 6 Double figureofeight on a bight Often called a bunny knot this knot is useful as it creates two loops that can be used to equalise anchors As the name suggests it is based on a double figureofeight with an adaptation to create two loops These can be easily adjusted and it is widely used in both industry and caving to make loads equal when a rope is secured to two anchors The knot can be dressed in a variety of ways some of which compromise strength In the tests the loops were tested individually This established that the loop closest to the loaded end tends to be slightly stronger than the other The knot is also stronger if the bight between the two loops is dressed towards the top of the knot In the tests the double figureofeight on the bight retained between 61 and 77 of the ropes full strength Further work on its ability to equalise forces between the two loops would be interesting 336 Bowline Figure 7 Bowline knot A common versatile knot quick to tie and very easy to undo which is useful for tying around large anchors It is very common in many areas particularly sailing It is unique in that it can be easily untied even after very large forces have been applied For example during the tests one knot will always break before the other in the lanyard This means the other has withstood a force very close to its breaking force Despite this the unbroken knot can be easily untied This knot showed the greatest variation in strength between the different ropes 55 to 74 337 Alpine butterfly Figure 8 Alpine butterfly knot This knot is frequently used as it can be used to create a loop in the middle of a rope that unlike the double figureofknots can accept loading in any orientation without deformation It is commonly used in industry to create a midrope belay or to isolate damaged portions of the It was tested for loop strength as with the other termination knots Loop strengths were comparable to the overhand knot In the tests it retained between 61 and 72 of the ropes full strength Further work on its effect on midrope strength would be of interest 338 Barrel knot Figure 9 Barrel knot This is commonly used in cows tails as it is small and forms a slip loop that tightens around the karabiner holding it in the correct orientation It can also be tied while under slight tension although the clove hitch is better for this purpose Due to its slipknot nature it has good energy absorbing abilities and gave the lowest impact forces in the knotted cows tails dynamic tests In the static tests breaking strength was found to be high comparable with a figureofeight at between 67 and 77 of the ropes full strength 339 Double fishermans Figure 10 Double fishermans knot This knot is used to join two rope ends either to extend a rope or to create a rope sling It is very difficult to untie if it has been heavily loaded Due to the amount of stretch when knots are heavily loaded it was only possible to test the double fishermans as part of a rope sling On all the tests the rope broke before the knot at forces of around 40 kN This is most likely due to the friction created around the pins at each end of the sling As the force is applied the knot tightens releasing rope into that side of the sling and hence reducing the force This extra rope must slip around the pins to equalise the forces on either side Inevitably friction impedes this process and the side of the sling without the knot is subjected to higher forces As the pins used have a very low coefficient of surface roughness this process would be exaggerated in a real situation Although the knot did not break it was subjected to very high forces and was one of the strongest tested By halving the maximum force reached during the test on the loop it can be stated that 20 kN will be the minimum figure that the double fishermans knot will hold on the particular rope tested 3310 Clove hitch Figure 11 Clove hitch knot Used to secure a rope directly to a post or bar it does not create a termination loop but instead grips the anchor directly Unlike any of the other knots tested it can be tied while the rope is loaded On most of the tests with lowstretch rope the clove hitches slipped without breaking at widely varying forces only partly dependent on the manufacturing process Interestingly with the dynamic rope the knots broke on every test at forces comparable with the overhand knot Overhand Figureof8 Figureof9 Figureof10 Bowline Figureof8 on bight Alpine Butt Barrel Figure 12 Knot strengths percent of manufacturers stated strength Overhand Figureof8 Figureof9 Figureof10 Bowline Alpine 13 Knot strength absolute kN34 CONTAMINATED ROPE TESTS A limited number of tests were carried out on sections of rope that had been exposed to contaminants The choice of contaminants was based on those which are likely to be routinely encountered on a work site Direct contamination such as chemical spills battery acid and engine oil were not considered as they are firstly easily avoidable and recognisable and secondly already subject to published data Two contaminants likely to be found on an industrial work site and on which little data was available were studied rust and bird droppings 341 Rust Sections of rope were left in a bucket filled with water along with around 1 kg of steel swarf metal shavingser about six months the sections were removed and left to dry Rust staining was seen on all the sections The worst affected parts were then tied up into lanyards using double overhand knots These were then tested in the same way as the other knots described previously When compared to the double overhand knot tests tied in new rope no additional reduction in strength was found This does not necessarily mean rust has no effect on polyamide ropes The amount of rusting that occurred was limited by the amount of oxygen dissolved in the water After some time this was used up and rusting slowed considerably Periodically removing the rope allowing it to dry and then reimmersing it would have resulted in far worse degrees of rusting This would also be a more accurate simulation of the conditions likely to be encountered in rope access Also whilst the rust itself may not cause damage the iron would form chelates with the organic acids that are likely to be formed in such wetting and drying scenario Both the chelates and the organic acids would be very likely to cause weakening of the nylon fibres More research in this complex area would be necessary before any definite conclusions could be drawn Table 4 Strength of rope contaminated by rust Type Diameter mm Average breaking force kN Rust contaminated rope Average breaking force kN Beal Lowstretch 105 1828 1834 Edelrid Lowstretch 105 1905 1947 Marlow Lowstretch 105 1979 1983 Beal Dynamic 110 1492 1457 CHELATE a chemical compound whose molecules contain a closed ring of atoms of which one is a metal atom 342 Bird droppings Sections of rope were left hanging on a tower where large numbers of birds roost To check that any effects where caused by the droppings rather than simply weathering more sections of rope were hung on an adjacent fence where no birds roost After about three months all the sections were examined The sections from the roost area showed staining and smelt strongly The sections from the fence were in good condition and were little different from new Again the worst affected sections were tied up into lanyards with double overhand knots and tested in the same manner as the other knots When compared to tests on new rope the rope showed a slight reduction in strength of around 2 This is most likely to be caused by the rope fibres being damaged by the organic acids in the bird droppings Again it would be interesting to investigate this further When compared to the tests on new rope both the weathered and the rusted Edelrid rope actually showed a slight increase in strength This is not as unlikely as it sounds the rope is not necessarily in its strongest form directly after it has been made A period of hanging or soaking is ideal to allow rope to relax and for any differential tensions created in the manufacturing process to be resolved This is one of the reasons why manufacturers suggest soaking and drying the rope before use the shrinking helping the rope to find its natural shape Whilst this is adequate for the other ropes the Edelrids waterproof coating means longer periods of relaxation and soaking are necessary Table 5 Strength of rope contaminated by bird droppings New rope Weathered rope Bird dropping contaminated rope Rope brand Average breaking force kN Average breaking force kN Average breaking force kN Edelrid 105 mm lowstretch 1905 1934 1774 343 Knots summary The knotted strength of a new polyamide kernmantel rope may be taken to be at least 55 of its ultimate breaking force This investigation therefore confirms that calculating the practical breaking load of a rope to be 50 of the ultimate breaking load will give a good margin of safety in all cases The overhand knot and the bowline are the least strong of the single loop knots The figureofeight is probably the best compromise between strength and complexity both in its double form simple loopon a bight double loopIn all the knot tests the dynamic rope was significantly weaker than the lowstretch rope This was to be expected as the treatment of the yarn to give greater elasticity also reduces its tensile strength However at the same time it also showed less variation between similar knots and gave more consistent results across different knots The static breaking load of knots in dynamic rope requires a different interpretation Single dynamic ropes complying with BS EN 892 do not have a stated static breaking load The relevant measurement is the maximum dynamic load sustained by the rope given a fallfactor 2 drop with a mass of 80 kg The knots in dynamic rope all held more than 150 of this figure Dynamic ropes carrying the weight of one person are never liable to break at the knot nor are they liable to break at the knot when used for raising or lowering with the weight of two persons on a rescue However their elasticity and resultant bounce limit their suitability for load hauling BRITISH STANDARDS INSTITUTION BS EN 892 1997 Mountaineering equipment Dynamic mountaineering ropes Safety requirements and test methods 4 ANCHOR FORCES 41 INTRODUCTION The object of these tests was to investigate the forces that anchors receive during a typical days access work Although the tests were of limited scope they gave a valuable insight into the loads involved While these tests are labelled anchor forces they also represent the forces that pass into the users harness Work was carried out at Firbank Viaduct Sedbergh Cumbria A portable load cell was installed on the working rope where it held the full weight of the technician A level 3 IRATA technician then performed a variety of operations and a laptop computer was used to continuously record the forces The operations and peak forces were as follows 42 ABSEILING From the anchor point the technician abseiled approximately 10 metres at a speed of 1 metre per second The average force was 075 kN the weight of the operative Slight jerks meant the force varied from 065 kN to 090 kN Figure 14 Graph showing forces generated when abseiling seconds43 ASCENDING The technician ascended back to the anchor point using the normal technique of hand and chest ascenders Again the average force was 075 kN but the maximum and minimum forces covered a greater range from 035 kN to 105 kN Figure 15 Graph showing forces generated when ascending The sequence of climbing is put weight onto footloop and stand up sit down to transfer the weight onto the chest jammer and finally bend leg whilst moving the hand ascender up the rope The peaks and troughs coincide with these movements which were then repeated Figure 16 Graph showing forces generated when changing from ascent to descent secondsForce WORK POSITIONING A combination of hand ascender and descender were used to ascend the rope a not unusual work positioning technique Forces were similar to those produced by normal ascent but slightly wider ranging from 030 kN to 110 kN Figure 17 Graph showing forces generated when ascending using a combination of ascender and descender The sequence of climbing was the same as in Figure 15 Ascending except that a hand ascender was not used In this case the footloop was attached to a descender and to move this upwards the slack rope was pulled through the descender secondsForce kN45 WORKING The technician remained at one point on the rope around 5 m below the anchor and performed a variety of simple work operations Again average forces were 075 kN with values ranging from 045 kN to 100 kN Figure 18 Graph showing forces generated whilst working at a single point seconds46 RIGGING The technician remained stationary in one position around 5 m below the anchor while carrying out a variety of rigging procedures such as tying knots and placing strops and slings around the structure The forces varied very little from 072 kN to 078 kN Figure 19 Graph showing forces generated when tying knots in one place operative stationary on seconds47 RAPIDLY Attempts were made to generate higher forces by carrying out conceivable poor practices such as abseiling jerkily and ascending as fast as possible Higher forces and low forces representing bounces were seen ranging from 035 kN to 160 kN Figure 20Graph showing forces generated when ascending and descending rapidly 48 SUMMARY In normal operations loads on anchors should not exceed 150 of the gross weight of the operative ie the weight of the operative and hisher equipment It is possible to increase peak forces to 200 of the gross weight of the operative by moving abruptly or braking Rescue procedures where static loading may be doubled should always be carried out as smoothly as possible The further down the rope from the anchor the operations were carried out the more rope was available to stretch and absorb peaks and troughs in the loading thus reducing force fluctuations seconds5 ROPE PROTECTORS 51 INTRODUCTION Textile ropes are softer than virtually any building or structural material with the exception of wood Therefore it is essential to protect ropes against abrasion wherever they run over a hard surface In the case of the protection is equally important but here it is to protect the trees cambium layer from the ropeariety of materials and devices are used in an attempt at edgeprotection These are often improvised for example rope bags scraps of carpet etc Purpose made protection devices range from metal rollers to simple canvas sleeves Test results will certainly vary if repeated with different ropes edges forces reciprocation times and speeds and different protectors It would be impossible to test all possible combinations However the results obtained give a sufficiently clear picture for good indifferent and poor protectors to be identified with some degree of certainty Before detailing the test methods and results it should be stated that the first line of rope protection should be to avoid all contact with sharp or abrasive edges whenever possible 52 METHODS Because all ropes commonly used in rope access are made from similar yarn and are of similar construction all the tests were conducted using the same type of low stretch rope Beal 105 mm Antipodes Three edges were used A rounded concrete edge coping stone radius approximately 10 mm concrete edge paving slab cut edge steel edge 50 mm by 50 mm steel angle radius 1 mmA mass of 875 kg was suspended from the rope This was cycled vertically through 50 mm over the edge at a speed of 500 mm per minute at a rate of 5 cycles per minute The machine was left to cycle and the rope was inspected at intervals for damage The levels of damage were classed as follows Slight damage any visible damage to the sheath such as cut or melted fibres Damage of this type often developed very slowly Severe damage cut bunches of sheath fibres or large melted areas While slight damage could slowly progress into severe damage beyond a certain point things would progress more quickly This was due to parts of the sheath beginning to catch on the edge causing rapidly escalating damage to the sheath When the test was continued beyond this point the sheath was usually quickly cut to the extent that it no longer protected the core If ropes reached this state the tests were stopped 53 UNPROTECTED Over an unprotected rightangled edge the rate of abrasion was in all cases rapid Over the sharp concrete edge it took 8 cycles to destroy the sheath Over the steel edge it took 15 cycles to destroy the sheath The results over the rounded concrete coping however were very different After approximately 600 cycles taking 2 hours only slight sheath damage was seen The rope slowly polished the concrete and abrasion only occurred because of a small bubble imperfection in the edge This was particularly surprising because in some subsequent tests with an edgeprotector in place far worse damage was seen over this same edge The only conclusion that could be drawn was that the protectors themselves were causing the damage 54 ROLL MODULE PETZL This device consists of a series of U shaped roller cages linked by screw link connectors maillon rapidesWithin the cages the rope is prevented from touching the abrasive surface by aluminium rollers with side rollers to prevent lateral movement By linking the appropriate number of cages together any variety of abrasive edge can be traversed safely by the rope Just two cages in the case of a rightangled edge more for gradual edgesAlthough the test was performed on all three of the edges the edge material is largely irrelevant as the rope does not touch it In the tests the only effects on the rope were flattening and black marks from the aluminium rollers The longest test was run for two hours a total of 600 cyclesThis result may be taken as representative of the use of any type of smooth rollers the only difference may be in practicability of use not in the totalegree of protection given 55 CANVAS SHEATH A rectangular strip of 15 oz natural shrunk canvas secured as a tube by means of velcro strips fixed around the rope Compared to other types of fabric protectors performance was impressive taking 270 cycles 54 minutes over the steel edge to wear through both the protector and the rope sheath Over the sharp concrete edge only slight wear was seen after 450 cycles 90 minutes56 POLYVINYL CHLORIDE PVC COATED FABRIC SHEATH Identical in construction to the canvas rope protector except that it was made out of a PVC coated polyester fabric 6 oz CAFLEX however was nowhere near as good as plain canvas with severe rope damage occurring after only 75 cycles on the steel edge It fared little better on the sharp concrete edge wearing through after 75 cycles with sheath failure occurring after 100 cycles Over the rounded concrete edge the protector did not wear through but the PVC coating rubbed off leaving stains on the rope and increasing friction and hence heat Damage then occurred due to melting rather than abrasion After 300 cycles the protector was not in a reusable state and the rope was both stained and glazed 57 COMPRESSED AIR FLEXIBLE HOSE PIPE This was chosen as being representative of the kind of improvised protector that could be made from materials commonly found on construction sites Although appearances suggest the pipe to be very robust it actually fared very badly in the tests Over the sharp edges the pipe wore through within the first 25 cycles 5 minutesthe rounded edge within 50 cycles 10 minutesg these periods the rope suffered much damage becoming coated in rubber and abraded Over the rounded concrete edge these constituted far worse effects than those caused by an unprotected edge 58 CARPET This is a form of improvised protector commonly used in the workplace There are many combinations of carpet construction and material mixes eg Axminster 80 wool20 polyamide Tufted 50 wool50 polypropylene Naturally performance as a rope protector will vary depending on the combination In this test programme only two types were tested The first was foambacked with nylon pile The second was a stiffer hessian backed type again with nylon pile Neither had particularly deep pile and they were obtained from active level three IRATA technicians as being typical of those in use However they were not felt to represent the height of durability 581 Carpet 1 Foambacked This performed very badly Over the steel edge it took a mere 25 cycles 5 minutesto wear through both the carpet and the rope sheath Over the concrete edges it was a little better surviving around 50 cycles 10 minutes before sheath damage began A point worth noting is that over the rounded concrete edge the rope suffered more abrasive damage than if it had been left unprotected 582 Carpet 2 Hessianbacked This performed slightly differently Over the steel angle it deteriorated very quickly taking less than 10 cycles to wear through both the carpet and sheath of the rope This was particularly surprising as the deterioration appears to be quicker than on the unprotected edge This could be due to the edge being slightly sharper at that particular point or it could be due to friction caused by the carpet heating the rope and allowing the edge to cut the fibres more easily Further investigation would be necessary to determine exactly what occurredOver the rounded concrete edge the hessian backed carpet lasted much longer than the foam backed variety wearing through after about 130 cycles As with the foambacked carpet slightly more damage was seen to the rope than with the same edge and no protection Over the sharper concrete edge sheath damage began after about 70 cycles Although the carpets were tested in single layers the providers of the samples suggested that in doubtful situations the carpet would always be used folded at least once 59 PVC COATED FABRIC SCRAPS SIMULATED ROPE BAG These were used to simulate a rope bag or similar being used for protection which the questionnaire highlighted as being commonly used The material used was the same as that used to make the PVC sheaths Using several layers of material was beneficial even on the steel edge no holes were created even after 300 cycles 60 minuteser as with the PVC sheath the coating rubbed off at an alarming rate Eventually a state was reached where the rope ran directly over the fibres of the fabric This increased friction and the rope did not run smoothly It seems the thickness of the four layers increases the edge radius sufficiently to prevent wear at a single point The condition of the material at the end of the tests was however poor The layers were fused together losing all their PVC at the wear point If this were a rope bag several uses as a rope protector would soon render it unusable 510 ROPE PROTECTORS SUMMARY Two types of damage were seen Firstly abrasion damage consisting of rope fibres cut by a sharp edge Secondly heat damage consisting of melting of rope fibres caused by friction between the rope and the rope protector The first conclusion is that protection is vital over any sharp edge While the roll module provides the highest level of rope protection canvas sheaths provide superb protection for their price A double layer of these would provide peace of mind in almost any situation From the tests it is also apparent that even a slight smoothing of an edge will dramatically reduce abrasion effects Any type of rope protection over these edges will appear to be working even though the protection is not actually required Over rounded edges some protectors will actually increase the risk of damage due to friction between the rope and the protector The PVC protectors provide little protection but are still better than nothing over a sharp edge Similarly the improvised protectors pipes carpet or rope bags will all provide some degree of protection in an emergency but are far from ideal In properly planned rope access work this situation should never arise Movement over edges is dependent on the relative positions of the anchors edge and load Where both the load and edge are far from the anchor point rope stretch will cause exaggerated movement over the edge Where the edge is close to the anchors but the load well below the majority of the stretch will occur below the edge causing limited movement over the edge What is less obvious is that large amounts of movement may be preferable as wear is spread over a longer section of rope Due to time constraints only parapetedge situations were investigated where movement is perpendicular to the edge Projections from the wall partway down the rope would need to be protected differently as would any situation where a sawing action across the edge was possible These areas would benefit from further study Another point to recognise is that any protector is only as good as the method used to hold it in place The PVC protectors in particular do not allow the rope to slide smoothly over them but instead adhere to the rope and move up and down with it gradually creeping out of position In rope access prevention is always better than cure In situations where ropes run over sharp edges the initial reaction should be an attempt to rerig the ropes to avoid them If this fails a rope protector may then be used Rerigging or deviations should always remain the preferred option On the basis of the tests carried out this would ideally be a roll module for a parapet edge and quality canvas sheaths for protection lower down the rope Other types of protectors such as 100 wool carpet and 50 mm diameter scaffold tubes may provide protection equal to if not better than canvas These could be the subject of further investigation 34 6 ROPE ADJUSTMENT DEVICES 61 INTRODUCTION There is an increasing range of devices on the market some originating in sport some designed specifically for industry As in prEN 12841 rope adjustment devices are divided into three categories Type A Backup devices Type B Ascenders Type C Descenders A key feature of equipment for rope access is versatility Almost all rope adjustment devices will have secondary uses especially during rigging for rescues etc This reduces the amount of hardware an operative has to carry and increases their operational abilities and safety margin Some newer devices are not as versatile as those currently in use and this must detract from their suitability for rope access Their specialist nature may however make them more suitable for certain specific purposes The line diagrams in the following sections are intended to show the principles of operation of the devices they are not intended to illustrate the entire device The diagrams are partial sections and have been reproduced at approximately 35 full size 62 TYPE A BACKUP DEVICES 621 Introduction The adoption of tworope systems one for progression the working roped one for security the backup or safety ropeuires that a third device be installed on the safety rope It must slide when required and lock on to the rope when required This is the origin and the function of the backup device The adopted definition of backup devices differs slightly from that in the standard prEN 12841 where they are called Type A Rope adjustment devices For the purposes of this report the definition adopted is A rope adjustment device for a safety line which accompanies the user during changes of position allows adjustment of the safety line and which locks automatically to the safety line under static or dynamic loading and which can be intentionally released while under load The performance and limitations of the backup device were one of the HSEs main concerns when commissioning this project Over the years the Petzl Shunt has become almost universally accepted as the industry standard and was stated as meriting particular attention At present the backup system incorporating the Petzl Shunt is effectively standardised by the IRATA Guidelines The Shunt is connected to the harness with a cows tail made from dynamic rope tied to the users required length The Shunt remains where it is placed on the secondary safety rope and must be repositioned whenever the user moves upwards or downwards When ascending this is done by pushing it up the rope ahead of the user When descending users fit the Shunt with a short cord to enable it to be towed downwards INDUSTRIAL ROPE ACCESS TRADE ASSOCIATION General requirements for the certification of personnel engaged in industrial rope access methods Edition 2 1998The IRATA Guidelines state that the Shunt should be maintained above waist level at all times to prevent fall factors above one The system works well and when used in accordance with the training has a good safety record However the Shunt has four potential drawbacks some of which may be shared by all of the devices The principal concern is that grabbing the body of the Shunt itself negates the cam action and prevents it arresting a fall As a grabbing action is a known reflex in fall situations this constitutes a potential danger in the Shunts performance However in normal use the ability to release a loaded Shunt by the same action is a very useful feature It adds to the versatility of the device and encourages the user to keep the Shunt in a safe high position without himher having to worry about whether it will become clamped to the rope and thus prevent descent when required The question is whether users can be trained to overcome the grabbing reflex in a fall incident B The second concern is the use of a cord to tow the Shunt when descending If this is either caught in the users equipment or simply remains held by the user during a fall the cam action is again negated IRATA members use various methods of holding the cord that are designed to prevent this but it remains a significant risk The third concern is over the Shunts relatively weak body strength The Shunt is designed to slip when overloaded and can be used on double or single ropes The slipping function negates the need for a strong body as high forces should be impossible to reach However if the Shunt is loaded when it is only a short distance above a knot on the rope it will be prevented from slipping by the knot and high forces could be achieved This situation is possible in rope access and could result in the Shunt releasing the rope at forces as low as 4 kN The problem is exacerbated when the device is used on a single rope as would be the case in rope access The fourth concern is the low force required to cause the Shunt to slip While this reduces the need for a very strong body it has one of the lowest sliding force of all the devices tested In a dynamic loading situation the Shunt could slip well in excess of 2 metres When combined with rope stretch the risk of a falling operative hitting the ground or structure during the fall is greatly increased These problems are largely the result of the adoption of a device that was not specifically designed for the purpose So what are the alternatives to the Shunt At present the alternatives can be split into two groups The first group is work positioning devices which are used in the same manner as the Shunt The second group replaces the work backup system with a fall arrest system which consists of a freerunning device that accompanies the user during changes of position Both alternatives have their advantages and disadvantages and require devices to fulfil different requirements 622 Backup devices What they must do or must not do general The backup device used in rope access is just as much a work tool as any other part of the system It must be under the control of the operator for proper effectiveness It should be possible to deploy it as a spare ascender should the need arise This means that a fallarrester device which simply follows the movements of the vertical worker reacting only to gravity or the removal of the effect of gravity by a freefall is not entirely appropriate for the job It may well be possible for freerunning fallarresters to incorporate features which allow them to switch to backup function Some fallarrest systems and techniques require the deployment of a guided type fall arrester for a flexible anchorage line This type of fall arrester defined in BS EN 3532 has to travel along the anchorage line accompanying the user without requiring manual adjustment during upward or downward changes of position but locking onto the line when a fall occurs The main advantage of a fall arrest system over a work positioning system is that it allows faster movement both up and down the rope Some devices can also work independently with no input from the user The backup system device can be ignored while the user changes position However as it hangs below the user and may not grab until the user has fallen some distance fall factors related to the device can be greater than two and the device must be able to handle the resultant forces safely To limit the length of the fall the link or cows tailto the harness should be as short as possible This system has the following drawbacks The backup device should be positioned to minimise any fall which may be incurred To this end it should always be positioned at or above the attachment point of the connecting linkor cows tail to the operative To allow for this positioning the backup device must have a positive hold on the rope so that the operative can slide it up or down the rope position it and know that it will stay there until he or she moves it The force necessary to tow the device or to dislodge it from its position should be known With a work positioning system movement may not be as simple but the user should always be in a safer position particularly if the user remains in one place for any length of time The backup system can then be adjusted so that an actual fall is prevented Some manufacturers have recognised these issues and have attempted to create fall arrest devices that can be locked in position when required One of these is the Komet Stick Run which features a catch that adds or removes the cams sprung action Without the spring the device runs very freely when it is installed it will not Similarly the instructions for the Troll Rocker illustrate how a second karabiner can be used to prevent the device moving freely on To be able to slide up and down the rope without snagging it is virtually certain that a device without aggressive teeth will be needed This is also a factor in considering what effect the device might have on the rope should a limited fall occur The device should be such that no possible fall could damage the rope to the point of stripping the sheath It is essential that the device can be attached to and removed from the rope at any point It then follows that this method of attachment should be practical in everyday use and that it should be secure It is highly desirable that the device should be deliberately releasable while under load This makes it far more practical as backup during descent so that if the device does become loaded it can be recovered without the user having to climb back up the rope At the same time it must be certain that either by product design or by operator training any possibility of the device slipping because of panic grabbing is eliminated There may be reasons to deploy the backup device on a link or cows tail lanyard length from a few centimetres eg a connecter up to the reach of the individual operator It is highly desirable that the backup device can be deployed at the end of lanyards covering this range Say 10 cm to 100 cmBRITISH STANDARDS INSTITUTION BS EN 3532 1993 Personal protective equipment against falls from a height guided type fall arresters Part 2 Specification for guided type fall arresters on a flexible anchorage line Devices certified to BS EN 567 Ascenders others certified to BS EN 3532 are currently being used as backup devices in rope access The disadvantages of some BS EN 567 ascenders are that they cannot be released while loaded and even when unloaded they are difficult to move down the rope This makes them particularly difficult to use during descent The disadvantages of some BS EN 3532 fall arresters are that by definition they cannot be positioned on the rope by the user as they only grab the rope in a freefall situation They cannot be used for fallprevention or work positioning without modification It is clear that neither standard is totally appropriate It is hoped that when prEN 12841 is finalised it will become the definitive standard for backup devices The devices tested fall into two groups Work positioning Petzl Microcender Petzl Rescucender Petzl Shunt and Wild Country Ropeman All of which are certified to BS EN 567 mountaineering ascendersFall arrest Ushba StopLock Komet Stick Run SSE Stop Go Tractel Stopfor D Troll Rocker All of which are certified to BS EN 3532 guided type fall arresters except the Ushba StopLock which does not carry the Certificate European CEarkThe devices come from a wide range of design backgrounds These vary from purpose designed mobile fall arrest devices to mountaineering ascenders Despite this the range of design principles is small The majority of devices Komet Stick Run Petzl Microcender and Rescucender Petzl Shunt Tractel Stopfor D are cam loaded rope clamps Force applied to the attachment point is transmitted via a pivot to a cam that traps the rope against the body of the device In all but the Petzl Shunt the pivot lies between the applied force and the cam In the Petzl Shunt the cam lies between the pivot and the applied force This design principle has been used for both work positioning and fall arrest devices Figure 21 Typical cam loaded and Petzl Shunt backup devices BRITISH STANDARDS INSTITUTION BS EN 567 1997 Mountaineering equipment Rope clamps Safety requirements and test methodsTypical cam loadedPetzl the other main principle Ushba StopLock SSE Stop Go Troll Rockerthe force is applied to the body of the device This features a fixed smooth block that traps the rope against a second pivoting block The upper end of the block is forced upwards by the rope attempting to straighten under load This force is transmitted through the pivot to the lower end of the block trapping the rope These three devices all run fairly freely on the rope Figure 22 Troll Rocker leftpeman from Wild Country backup devices latter shown with karabiner attached The Wild Country Ropeman is different again working on a bodyloaded principle most common in Type B devices ascenders A sprung toothed cam contacts the rope that lies in a channel When force is applied to the body of the device the ridgedstyle teeth bite into the rope pulling the cam into the channel and trapping the rope This device will only work when it has a karabiner attached as the rope is trapped between the cam and the karabiner It is worth noting that the Ropeman would not ordinarily be included in a list of backup devices it was added because it was found to be in use as such when the questionnaire was returned 623 Tests The nine devices each underwent four tests as specified in prEN 12841 see 32 of this working strength section 423 prEN 12841Device to hold a force of 4 kN for 3 minutes This test is designed to check that the device can comfortably exceed its safe working load without deformation or damage to the rope The test originated in BS EN 567 an ascender standard where 4 kN represents a force at the limit of what could be achieved in normal usage but below the forces at which toothed cam ascenders will inevitably damage the rope When applied to backup devices which are designed to slide before high forces are reached it is less suitable Passfail results related to this test may simply indicate the need for a different test practice this type of test is useful to determine the static force at which slippage begins The working strength tests were performed on four different ropes Beal Antipodes 105 mm low stretch Edelrid 105 mm low stretch Marlow 105 mm low stretch and Beal Apollo 11 mm dynamic Table 6 Backup devices and forces to initiate sliding on the rope Force to slip under static load kNDevice Rope Beal Edelrid Marlow Dynamic Komet Stick Run 31 25 27 23 Petzl Microcender 35 22 32 34 Petzl Rescucender 444Petzl Shunt 23 25 25 27 SSE Stop Go 21 28 24 34 Tractel Stopfor D 25 22 27 25 Troll Rocker 444Wild Country Ropeman No slippage cuts sheath at approximately 4 kN The Ushba StopLock was not tested see later comment in section 624 Dynamic performance section 425 prEN 12841 May 2000Peak impact force and slippage with a fall factor 2 drop with a 100 kg mass The tests were carried out using the catch plate rig at Petzl See section 1445 in the Appendix for details Perhaps the most relevant test this test investigates the energy absorbing abilities of the devices in a worstcase scenario a fall factor 2 with an inelastic lanyard 100 kg represents the likely upper mass limit of an operative plus equipment A large operative might also be tall and therefore require long cows tails The total lanyard length was therefore simulated as being one metre including connectors giving a factor 2 fall of 2 metres A catch plate method was used for these tests This eliminates an actual lanyard from having to be used and results in more consistent results The dynamic tests were performed on four different ropes Beal Antipodes 105 mm low stretch Edelrid 105 mm lowstretch Marlow 105 mm lowstretch and Beal Apollo 11 mm dynamic Three replications were carried out on each rope type giving twelve tests on each device Figure 23 Type A Backup devices dynamic performance Note Maximum slip limited to 25 m by test rig force kNSlippage mStick GoStopfor DRockerMinimum static strength section 424 pr EN12841 May 2000Hold a force of 12 kN for three minutes The relationship between the minimum working and minimum static strength test is based on factors of safety With a minimum working strength of 4 kN the 12 kN static test gives a safety factor of 3 The severity of this test is dependent on the amount of damage the device is allowed to sustain All devices require a stop on the anchor line usually a knot to prevent slippage at such high forces and this causes abnormal loadings that can damage the device As long as the device does not release or damage the rope it is argued that some deformation here is acceptable Any evidence of fracture however should constitute a fail A device should also be considered as failed if it becomes unusable In the minimum static strength only one test on Edelrid rope was performed due to the expense and up to four of each device The rope is irrelevant in this test as it simply acts as a stop against which the device can be pulled Ultimate static strength Initially it was intended as a final test to load all the devices to destruction However the severity of the minimum static strength test meant that most devices had already reached their limits during this test The devices which were apparently still usable were those with a machined aluminium body It was deemed not necessary to test these devices to their ultimate strength for two reasons it is extremely unlikely even with abuse that forces will exceed 12 kN in the workplace the devices would have been tested on a knotted rope and knot strength would have limited the maximum force which could have been applied to the devices 624 Ushba StopLock Material Titanium Weight 132 gm Design principle Body loaded Method of use Fall arrest Figure 24 Ushba 221StopLock222 backup device Markings Front face 223EN567224 AND 223UIAA224 on the rear The device does not show the Certificate European CE in use Installation on the rope is easy although the device must be unclipped momentarily It runs quite freely both up and down 105 mm rope although occasionally sticks when descending It can be tensioned onto the backup rope easily but if unloaded briefly it may drop down the rope It can be released from the loaded position easily and is generally easy to use and very compact Test performance The Ushba 221StopLock222 fared very badly in the dynamic tests Only two devices were available for the dynamic tests and both of these cut the rope completely without any slippage at a peak force of 55 kN The devices were too distorted and damaged to test again This would appear to be a serious design fault and the StopLock cannot be recommended for use as a backup device No further tests were carried out 625 Komet Stick Run Material Steel Weight 474 gm Design principle Cam loaded Method of use Fall arrest Figure 25 Komet Stick Run backup device Markings On the spine 223KOMET STICK RUN646000 DRISSE D105 EN 3532 OU CORDAGE 3T PA D12mm224 There is also an 221up222 arrow Performance in use To attach and remove it from the rope requires a bolt to be screwed and unscrewed This is a little fiddly but as the device remains attached to the operative it cannot be dropped The Stick Run has two different settings it will stick or run It runs freely on the rope with a small brake wheel in one position for descending and will only move up the rope in the other for ascending Simply adding or removing a spring action from the cam achieves this change of action Effectively this means the user can choose whether to have a fall arrest or a device However as such it is a compromise and does not excel in either situation When used with a lanyard the active run position is a little too free on 105 mm rope and relies mainly on the devices weight meaning the device may take time to deploy in some situations This could possibly be remedied by modifying the brake wheel However when used attached directly to the harness the free action is appreciated When in the 221Stick222 position it can easily be tensioned onto the backup rope for safety or to aid positioning It is very difficult to release when loaded Note Since the tests the Stick Run has been slightly redesigned with a smaller completely smooth brake wheel and an additional light spring in the cam Test performance The Komet Stick Run failed to hold the 4 kN minimum working strength test slipping at approximately 3 kN It passed the 12 kN hold test but was severely distorted In the dynamic tests long slippage distances reflected the low slippage force On two tests on Edelrid rope the device hit the buffer at the end of the test rig On ten out of twelve tests the peak impact force was less than 3 kN The two tests that exceeded this were on Marlow rope Despite the higher impact forces over 4 kN slippage was comparable to the other tests at approximately 175 metres Petzl Microcender Material Aluminium Weight 162 gm Design principle Cam loaded Method of use Work positioning Figure 26 Petzl Microcender backup device Markings UP at the top 223EN567 CE 0197224 plus characters showing rope diameters from 9 to 13 mm and 38 to 12 inches inclusive There is also a small 223224 instructions symbol outline of a in use The device is installed on the rope after removing the axle by means of a small catch The device remains clipped in and cannot be dropped It stays wherever it is placed and can easily be moved up and down There is a hole in the device that will accept a cord for towing downwards It can easily be tensioned onto the backup rope to aid positioning Release when loaded is very difficult Test performance In the working strength test it was found to slip at approximately 3 kN Despite the 12 kN force applied in the minimum static strength test the device showed no sign of any damage In the dynamic tests it performed well on the Edelrid and Marlow ropes On the Beal rope however the results were not consistent showing a steady increase in slippage as the test progressed As the same device was used for all the tests on Beal rope this could be attributed to polishing of the cam surfaces However the same did not occur with any of the other ropes The relationship between slippage and maximum impact force was however very consistent 4pC627 Petzl Rescucender Material Aluminium Weight 250 gm Design principle Cam loaded Method of use Work positioning Figure 27 Petzl Rescucender backup device Markings On one side of the body 221UP222 arrow 223EN567 CE 0197224plus characters showing rope diameters from 9 mm to 13 mm and 38 to 12 inches inclusive and an 223224 symbol with a pictograph of an instruction book On the reverse there is a large engraved arrow with the words 223UP224 and 223LOAD224 Performance in use This is a larger version of the Microcender and functions as such It is perfectly usable as a work positioning device although the spring is a little weak and the device may fall down the rope instead of staying where it is placed It can easily be tensioned onto the backup rope to aid positioning Release when loaded is very difficult Test performance In the working strength test it did not slip During the minimum static strength test it was seen to slip at approximately 7 kN After the 12 kN force was applied in this test the device showed no sign of any damage In the dynamic tests it performed fairly well in grabbing the rope although impact forces were a little high compared to other devices approximately 6 kN on most of the tests Slippage however was consistently low 1 m or less on 12 out of 13 tests One test was something of an anomaly with a low impact force of 34 kN and a large slippage of 16 m Unsurprisingly this was on Edelrid rope However an extra test was carried out and this proved consistent with the other figures The only feasible explanation is that the device was not installed on the rope quite as firmly on this test Throughout the test programme the Edelrid 105 mm low stretch rope was found to be the supplest and rope tested See section 24 221Ropes summary222 for more explanation GktJWrCqD Petzl Shunt Material Aluminium Weight 186 gm Design principle Cam loaded Method of use Work positioning Figure 28 Petzl Shunt backup device Markings On one side of the body 223DOUBLE ROPE with characters to show rope diameter 8 mm to 11 mm inclusive SINGLE ROPE with characters to show rope diameter 10 mm to 11 mm inclusive CE0197224 and an 223224 with the outline of an instruction book On the other side there is an outline of a figure with raised hand and 223WARNING DANGER PROPER TRAINING IS ESSENTIAL BEFORE in use Installation on the rope requires it to be unclipped with the attendant risk of dropping The method is easy however and the device remains where it is placed It is easily moved both upwards and downwards by hand A hole in the back of the cam allows a cord to be attached for towing downwards It can easily be tensioned onto the backup rope to aid positioning Release when loaded is straight forward Test performance The working strength test simply served to demonstrate the low force at which the shunt will slip 23 kN to 25 kNer when prevented from slipping in the minimum static strength test the frame bent releasing the rope at only 55 kN This force is a little too low for comfort giving a very small margin of safety In the dynamic tests it performed poorly Slippage figures were high the shortest being 15 m while the longest slips hit the buffer over 25 m below On most of the tests impact forces were below 25 kN although on two of the tests on dynamic rope higher figures were achieved when the device snagged and severed the sheath On all tests the corner of the frame left a mark down the sheath as it slipped SSE Stop Go Material Aluminium Weight 484 gm Design principle Body loaded Method of use Fall arrest Figure 29 SSE Stop Go Backup device shown with side plate swivelled through 180Markings On the front there is an 221up222 arrow and 223EDELRID USE ONLY ROPE 370 12224 On the rear face an 221up222 arrow and 223CE 0335 01962224 Performance in use The device must be unclipped momentarily for installation The cam is not sprung instead a small brake helps prevents downwards movement Raising the device by raising the attachment releases the brake and the device moves freely upwards Careful positioning also allows it to follow the worker down the rope When the user falls the upward force on the karabiner is removed and the brake is activated speeding up the arrest of the fall The body and cams of the Stop Go are significantly larger than the other devices working on the same principle resulting in a device that is very kind to the rope An additional handle is supplied to release the cam when loaded this does not work well and would be ignored by most users The handle is separate and has to be fitted to the device for each use Test performance In the working strength test it was found to slip at between 2 kN and 35 kN depending on the rope used In the minimum static strength test the device distorted badly at approximately 11 kN although the device did not release the rope In the dynamic test conditions the device performs quite well although not too consistently On dynamic ropes it gives excellent results comparable to the Rocker However on other ropes the results vary widely The highest impact force was achieved on Marlow rope 65 kN although on many of the tests it was approximately 4 kN Although a wide range of results was obtained all were within acceptable margins 6210 Tractel Stopfor D Material Steel Weight 616 gm Design principle Cam loaded Method of use Fall arrest Figure 30 Tractel Stopfor D shown without the supplied On the side 223Drisse 330 11 Kernmantel rope EN 3532 CE0082224 There is an 221up222 arrow on the operating mechanism Performance in use This new device has been designed specifically for industrial fall arrest and has a couple of unique features Like the Stick Run it can be installed on the rope without unclipping but it also has the advantage of simply clicking on the rope without the need for any screws to be tightened A small catch arrangement also prevents the device from being installed upside down on the rope The device comes complete with a 03 m tape or 06 m static rope lanyard already installed The instructions suggest the 30 cm tape lanyard is used for fall arrest applications and the 60 cm static rope lanyard for rope access These lengths do not allow for all variations in user size and technique For the purpose of the tests the lanyard provided was removed as would have been required in prEN 12841However it was made of very inelastic tape which is unlikely to have absorbed any appreciable fall energy On the other hand the modification to the test discussed in 6213 would have allowed the device to be tested with the lanyard as supplied With the only sample available for test concern was raised about the durability of the spring arrangement in the latch It is understood that the manufacturer has since modified this spring arrangement The high weight is noticeable when the device is used The supplied lanyard was completely static in nature always a concern in a fall arrest system as it will absorb little energy The device moves up the rope well and if adjusted correctly will also run down the rope very freely as the operative moves down the rope Due to the length of the lanyard and the device222s weight and design it may allow a long drop before it deploys Test performance In the working strength test it was found to slip at approximately 25 kN It survived the minimum static strength test undamaged In the dynamic tests it did not perform too well slip distances were excessive hitting the buffers on four occasions and never slipping less than 14 metres When the weight and freerunning capabilities of the device are taken into account some very long falls are conceivable As this device seems most suitable for the fall arrest market this gives cause for concern 6211 Troll Rocker Material Aluminium Weight 162 gm Design principle Body loaded Method of use Fall arrest Figure 31 Troll Rocker backup device Markings On the opening plate EN358224 and the name 223Rocker224 and the Troll trade mark On the main plate there is the outline of a figure with an upraised arm to show which way up to use the device Performance in use In appearance the Rocker is very similar to the Ushba Stop Lock although its aluminium construction makes it a little bulkier than the titanium device In use it feels very similar although a weaker spring means it runs a little more freely As is recommended in the instructions it was found best to keep it on a short link 15 cm to 25 cm the Rocker will then run freely up and down the rope as the operative moves Some sticking was encountered during descent however the short link and easy release meant it did not cause a problem With practice and careful positioning this occurred less oftenThe attachment hole is also large enough to allow a second karabiner to be fitted to prevent free movement on the rope as shown in the instructions However in normal use the Rocker had a tendency to catch on the screwgate of the karabiner making crossloadings possible Test performance In the static tests it was found to slip at approximately 35 kN to 45 kN depending on the rope At high forces over 10 kNe side plate distorted and cut the rope In the dynamic tests it produced extremely good results The results not only show the best impact force and slippage relationship but also the greatest consistency of any of the devices tested Slippage remained under a metre on all but one test with impact forces between 32 kN and 48 kN The light weight and moderately free action mean the device will arrest falls quickly without long drops Wild Country Ropeman Material Aluminium Weight 60 gm Design principle Body loaded toothed cam Method of use Work positioning Figure 32 Wild Country Ropeman backup device shown with karabiner attached in diagram Markings On one side plate 223CE960120 3301011mm ENGLAND224 On the other plate 223WILD COUNTRY Ropeman224 and the outline of a figure with raised in use This tiny device was originally intended as an emergency ascender for mountaineering Compared to the other devices it will not move freely on the rope particularly downwards making it difficult and time consuming to use To descend the cam must be pulled away from the rope and held while the device is moved This device is extremely difficult to remove under load Test performance In all the tests the results reflect the design of the device As a small bodyloaded toothedcam ascender experience has shown a likelihood that the sheath of the rope would be stripped rather than the device slip In a static pull this occurred at approximately 6 kN In the dynamic tests this occurred at impact forces as low as 35 kN although on Beal rope a maximum of 63 kN was reached On the third test with Beal the Ropeman actually severed the core as well breaking the rope These results are clearly unacceptable for a backup device While correct use of a passive backup device can render only marginally suitable devices safe in this case the design principles may have been pushed too far The only advantage the Ropeman offers is that it will operate correctly and safely even if grabbed by the user This is a function of its bodyloaded design principle rather than a unique feature It is however the principle reason why the company concerned adopted it The reason that the Ropeman was adopted rather than other devices is due to the cam design The cam has teeth too large to penetrate the rope sheath allowing it to be dragged down the rope by a cord attached to the cam NB During the test programme Wild Country released the Ropeman MkII This has a redesigned cam The cam design has been significantly altered to a design closer to those of other ascenders This includes the addition of teeth too sharp to allow it to be dragged down the rope Correspondence with the industrial users of the Ropeman confirmed that they had discontinued its use 6213 Summary of test performances The minimum working strength test was not found to be particularly useful in relation to backup devices A modified static test would be useful but the sliding force would have to fall within a stated range rather simply above 4 kN as required by the present test There is no need for the backup device to withstand a force of 4 kN before slipping indeed this could be in some cases A suggested range for a static slippage test is between 25 kN and 6 kN It can be argued that the dynamic performance test is even more severe than the worstcase scenario It allows for the backup device to be connected to the operative by a rigid strop or lanyard which is something that would never be recommended The only two ways that the energy of the test fall can be absorbed are through the stretch of the rope on which the backup device is mounted and the slippage of the device on that rope In reality the backup device should always be attached to the user by a dynamic lanyard thereby providing a third element There is therefore a good argument for allowing the manufacturer to provide as a subsystem both backup device and connecting lanyard and for the dynamic test to be conducted as a fall factor 2 drop onto the integral connecting lanyard In the dynamic performance test the degree of slippage is broadly inversely proportional to the peak forces achieved see the Appendix 9 This is expected from the physics involved low slip distances resulted in high impact forces and viceversa Within this relationship the different devices display a wide range of slippageimpact force Interestingly the nature of the device is not reflected in the results which bear little relationship to the design or principle of the devices It is suggested that the best results lie in the central area of the distribution see figure 23 where both extreme impact forces and long slip distances have been eliminated Of these results the very best are those closest to the origin where the lowest combination of both impact forces and slippages lie Ideally devices should perform consistently Almost all the devices proved inconsistent Using the slippageforce criteria described above the Troll Rocker was the best performer and showed the highest degree of consistency The Petzl Microcender and the SSE Stop Go also performed well but of the two neither showed any reasonable degree of consistency the Stop Go being the more inconsistent The Petzl Rescucender is the next most consistent performer showing a similar range of slippage figures to the Rocker but with impact forces in a range approximately 2 kN higher Three devices slipped 25 m such that they hit the buffers on the test rig These were the Petzl Shunt Komet Stick Run and the Tractel Stopfor D A secondary factor to take into account is the state of the rope following the test Opinion was that slight sheath damage may be acceptable although not ideal but severe sheath damage should invalidate even excellent test values The kindest device on the rope was the SSE Stop Go Following the test it was almost impossible to tell if the rope had been used Conversely two devices succeeded in cutting the rope completely the Ushba Stop Lock and the Wild Country Ropeman The Petzl Shunt and the Komet Stick Run both stripped the sheath when tested on dynamic rope although not on every test Beyond this the damage was more difficult to quantify Devices such as the Petzl Microcender and the Troll Rocker left a short length of rope heavily glazed and furred on one side The Petzl Shunt left a single long cut down the side of the rope sheath It is not possible to say which is worst Tests on damaged sections of rope suggested that ultimate strength is not reduced to a level where it becomes dangerous 6214 Summary of Backup devices Despite identical test setups inconsistent results were the norm rather than the exception One reason for these is rope type Some devices perform better with certain makes of rope How this relationship changes with worn rope is uncertain For a device to be recommended as compatible with a specific rope a study would have to be made with ropes of varying age and condition Fall arrest type devices had a contrived advantage in the dynamic tests by being already locked on to the rope by the weight of the catch plate See Appendix 4 for a description of the test equipment of which the catch plate was partn a real situation this might not occur until the user and the device were falling There is concern that with a downward acceleration less than g for example in rapid abseils the device might not lock onto the rope at all A very short link to the harness may help locking on to the rope to occur as quickly as possible A short link does however increase the chance of the device locking when this is not wanted As they operate largely by themselves for example on the rear attachment of a harness predictable performance is therefore essential Only one device the Tractel Stopfor D comes with a nonadjustable and nonremovable lanyard attached There is scope for further research into the effect on performance when these devices are used with different length lanyards With the work positioning devices operator attention is required at all times The degree of safety provided is dependent on sensible positioning of the device by the user With very careful use almost any device can be kept in a position where the impact of a fall would be negligible Despite this it cannot be recommended that any cam toothed or aggressively ribbed bodyloaded ascender be used for backup At the time of the tests only a limited number of operatives were using such a device the Wild Country Ropeman ascenders with smooth cams should be considered None of the devices stood out as being the ideal backup device All suffered from shortfalls somewhere in their performance However much has been learned While fall arrest devices can work well and may be applicable to many situations they are not suitable for rope access without modification to allow them to remain in position on the rope Such modification could for example be by the application of a spring or additional karabiner loading as shown by two of the devices testedorrect operation of a back up device as recommended by the IRATA Guidelines on the use of rope access methods for industrial purposes results in a very safe system where the possibility of a fall factor greater than 1 is eliminated This has allowed trained operatives to use devices whose performance and strength may not be ideal effectively and safely The shortfalls of the Petzl Shunt have been clearly seen and the industry should now be developing devices which fulfil the requirements discussed above One serious concern remaining is the grabbing reflex of the operator in a fall situation With many devices there is a good chance that performance will be impaired if anything is in contact with the device The consequences of the user actually grabbing the device in a fall are potentially catastrophic many devices will be completely disabled by this action Ideally this should be designed out of the device However at present all devices suffer to some degree from this problem Training users to overcome this reflex is essential at least until a device is available which will pull down the rope when required but remain secure if grabbed in panic INDUSTRIAL ROPE ACCESS TRADE ASSOCIATION Guidelines on the use of rope access methods for industrial purposes Edition 2 Revision 1 0100 63 TYPE B ASCENDER DEVICES Figure 33 Typical hand ascender Type B device chest ascenders similar but with smaller body and no handle Rope clamps Type Bre principally used for ascending the rope and hence are generally called ascenders or jammers All type B devices clamp onto the rope but may be connected to the user in different ways For industrial use they are usually either fastened into the suspension point of the user222s harness or they are fitted with a footloop so that the user222s weight is transmitted to the device when he stands in the loop In the first case the device is held vertically against the chest by a second attachment point on the device which connects to the upper torso part of the harness An ascender used like this is known as a chest ascender This chest ascender arrangement allows automatic body movement when ascending while the ascender with a footloop is pushed up the rope manually The latter may therefore be referred to as a hand ascender Ascenders may be attached in other ways for example to the knee or ankle but this is not common practice on the worksite To ascend the rope the operator stands up in the footloop keeping himself upright by holding the hand ascender while the chest ascender slides up the rope Sitting down in the harness suspended by the chest ascender then allows the hand ascender to be slid further up the rope In the workplace ascenders used for upward progression are of the toothedcam body loaded type The questionnaire confirmed that there were no exceptions to this The only ascender standard currently in existence is BS EN 567 There are other ascenders that meet this standard but some are unsuitable for any work application Others may be more suitable as Type A 226 backup devices The reasons for the use of bodyloaded toothed cam ascenders are that they slide easily and directly up the rope hold immediately and positively when subject to a downward force do not cause the user to lose any height gain as they are loaded are easy to install and remove from the rope these devices work on the same bodyloaded toothedcam principle and differ only in detail All consist of a channel in which the rope is trapped by a toothed eccentric cam Only a light locating spring and the teeth initiate the gripping action no force is directly applied to the cam For this reason extremely dirty or icy ropes can cause problems with the operation of the device The cams of two manufacturers incorporate camcleaning devices slots to counter this Six ascenders in total were tested three hand and three chest types These device were tested against three of the tests specified for Type B devices in prEN 12841 see 33 in this standard A Minimum working strength see section 446 prEN 12841 Device to hold a force of 4 kN for 3 minutes Test originally from BS EN 567 All the ascenders on test had been previously tested to this standard prior to their release onto the market and unsurprisingly all passed B Dynamic performance see section 448 prEN 12841 Peak impact force and slippage were measured with a fall factor 1 drop of a 100 kg mass The device was located on the rope 1 metre below a rigid anchor and the weight released from the height of the anchor The tests were carried out using the catch plate rig at Petzl See section 1445 in the Appendix for details Given that this type of ascender is designed to grip the rope without slippage the only way that the energy of the fall can be absorbed is by the stretch of the rope and sliding of the sheath down the core if or when it is severed It is therefore as much a test of the rope used as of the device itself All devices of this type will cut the sheath in an impact of this severity The fall is only arrested when the sheath bunches and grips the core usually after about a metre of slippage It should be noted that the ends of all the test ropes had been cut with a hot knife and thus the sheath and the core were bonded together at this point If the ends of the sheath and core are not bonded then the ascender can run off the end of the rope A knot will prevent this The impact forces sustained in these tests are summarised in Appendix 12There is a strong argument to say that this test is irrelevant The action of these devices on kernmantel rope is such that the sheath of the rope is held without slippage by the toothed cam When the dynamic force reaches a figure at which the sheath breaks the severed sheath slides down the rope core This test adds very little to the minimum working strength test This could be extended so that first the device would be loaded to 4 kN for three minutes as normal then it could be pulled to sheath failure and the figure recorded C Component body test see section 416 prEN 12841 Device to hold a force of 15 kN for 3 minutes across attachment points Although in prEN 12841 this test is aimed at all rope adjustment devices not all have the two attachment points necessary for the test Type B devices all have at least two attachment points and therefore qualify The test is designed to safeguard against the unlikely risk of the ascender being used as a link between two connectors for example in a rescue and does not apply to the normal operation of the device at all 631 Camp Pilot Material Aluminium SheetWeight 222 gm Design principle Body loaded Method of use Hand ascender Figure 34 Camp Pilot Type B ascender device Description The cast steel cam has a relatively small concave contact face 35 mm long This has 17 small teeth distributed in pairs either side of a plain central strip This strip appears to have been designed as a slot but not actually manufactured as one The conical teeth are 2 mm long with fairly sharp points The axes of all the teeth are roughly parallel with the top surface of the cam Markings Next to the rope channel includes outline of man indicating correct way up EN 567CE0123 ROPE min 330 8 max 330 13 The marks are lightly etched and painted Performance in use The pushbutton catch design works well and has a good positive action The rubber handle is comfortable with plenty of room for large hands However the broad handle means the load is some distance from the rope and the device rotates slightly when loaded Installation on the rope is more difficult than with the other ascenders as the slot is narrow and curved However once on the rope it moves up and down well although the sharp teeth will snag the sheath if care is not taken when moving down the rope Test performance Both the static tests were passed Following the 15 kN component body test some distortion was seen This was visible around the top attachment hole where the thin metal forming the top of the hole had stretched slightly In the dynamic tests the Camp Pilot cut the sheath at slightly lower impact forces 41 kN to 52 kNthe other devices See the Appendix This is possibly due to the small area of the cams contact face and the nature of the teeth These are quite sharp and protrude almost horizontally Following the dynamic tests it was quite difficult to remove the Camp Pilot from the rope This is because the rope channel opens up slightly when the rope is forced into it under high forces When the load is released the channel springs back trapping the rope against the cam 632 ISC ascender Material Aluminium Extruded and then machinedWeight 364 gm Design principle Body loaded Method of use Hand ascender Figure 35 ISC Type B Hand ascender device Description This ascender has been milled from an extruded aluminium section The cam has a concave contact face 45 mm long uniformly covered with 46 teeth arranged in alternating rows of 3 and 4 teeth The teeth are short 1 mm and stumpy with rounded points The teeth222s axes are perpendicular to the cam face The plastic handle is not as comfortable as the others particularly for large hands The device is not particularly broad and so sits well when vertically loaded Installation on the rope is very easy and it moves up and down the rope well The teeth are not sharp enough to snag on the sheath Markings On the front of the handle a rather ambiguous arrow pointing upwards and a small 0120CE mark On the rear of the handle 330 ROPE MIN 9mm 13mm MAX The marks are lightly etched on a painted background On the rear of the body is a machine stamped batch number In use it is noticeably heavier than the other devices but is not detrimental to performance or ease of use The extruded section is clearly very strong and gives a reassuring solidity to the device In contrast with the rest of the device the catch an aluminium lever feels slightly flimsy Test performance In the static tests it was the only device to show no distortion whatsoever Following all the tests the cam released easily no matter what force had been applied The 15 kN component body test was passed without any distortion The rope channel is sufficiently strong to prevent it opening even slightly when under load In the dynamic tests it cut the rope sheath at forces comparable to other devices 48 kN to 66 kNer in contrast with the other devices it could be removed easily following the test 633 Petzl Ascension Material Aluminium SheetWeight 198g Design principle Body loaded Method of use Hand ascender Figure 36 Petzl Ascension Type B hand ascender Description The contact face of the cam is 32 mm long with a central vertical slot to assist the removal of mud from the rope and cam interface The face is covered with 26 teeth arranged in rows The teeth222s axes are angled downwards at an angle constant to the cam face ie they are not all parallel The teeth are short 1 mm longairly sharp In the body there is a pressed stop above the cam to help stop the cam pulling through the channel when under extreme forces Markings stampedext to the rope channel outline of man indicating correct way up and characters to show rope diameter from 8 to 11 inclusive On the front base CE0197 and on the rear base EN567 On the rear of the body there is a small 223224 instructions symbol outline of a in use The rubber handle is comfortable and the plastic catch easy to use although strongly sprung Installation on the rope is easy and the device moves up and down the rope easily Care must be taken when moving downwards to ensure the sharp teeth do not snag the sheath There are two attachment holes at the bottom of the handle The handle is canted slightly to allow these to lie in line with the rope with the result that it seats well when loaded Test performance Both the static tests were passed although some distortion was seen following the component body test This was visible as distortion and crazing of the thin metal forming the top of the upper attachment hole Dynamic performance was on a par with the others tested stripping the sheath at between 45 kN and 65 kN As with other stamped aluminium devices an impact of this severity results in a slight opening up of the rope channel visible as crazing of the anodising on the rear of the device Following the test the rope was difficult to remove as the channel tried to spring back trapping the rope 634 Anthron AC30 Material Aluminium SheetWeight 146 gm Design principle Body loaded Method of use Chest ascender Figure 37 Anthron AC30 Type B Chest ascender Description The cast steel cam has a fairly small contact face 33 mm long The face is covered with 18 small teeth with a large lug at the base The purpose of the lug appears to be to prevent the teeth scratching the inside of the rope channel The teeth are 1 mm to 2 mm long fairly sharp and are set at a slightly downward angle constant to the cam surface The sides of the cam are grooved to aid the removal of mud from the ropecam interface Markings stampedthe top of the rope channel an ambiguous doubleheaded arrow and 223ROPES 330813mm224 on the back of the body 223CE0123224 Performance in use When the cam is open the wide slot accepts the rope easily The top hole is slightly smaller than on other chest ascenders but easily accepts a 10 mm karabiner Once installed it moves up and down well Care must be taken when moving downwards to ensure the sharp teeth do not snag the sheath The very strong catch spring can make releasing the rope difficult Test performance Both the static tests were passed although some distortion was seen following the component body test This was visible as stretching and crazing of the anodising surrounding the upper hole However it was the only one of the three chest ascenders to pass this test In the dynamic test it produced slightly higher peak impact forces 5 kN to 7 kNthan any other device In contrast with the type A and type C devices this is a good sign as it shows the toothed cam does not cut the rope sheath as readily as other devices The reasons for this are unclear however it may be due to the action of the small lug at the base of the cams contact 635 Kong Cam Clean Material Aluminium SheetWeight 156 gm Design principle Body loaded Method of use Chest ascender Figure 38 Kong Cam Clean Type B ascender The cast steel cam has a large contact face 42 mm long with four transverse slots to assist the removal of mud from the cam and rope interface 24 teeth are arranged in rows across the face Both the teeth and slots are contained within a concave groove in the face of the ascender This groove decreases in radius from top to bottom to accommodate different rope sizes The teeth are small 1 mm to 15 mm longrounded ends and are all aligned parallel with the top surface of the cam Markings On the rope channel diagram of device and rope with arrow pointing up On the back of the device 223CE0426 UIAA 330 8 12 mm The marks are lightly etched Performance in use The device is easy to install on the rope as a result of the wide slot and curved rope channel It moves up and down the rope reasonably easily although care must be taken when descending to ensure the sharp teeth do not snag the sheath When ascending with little weight of rope below the device it does not always run smoothly as the rope catches in the channel The release catch can be easily operated with either finger or thumb to release the Test performance The minimum working strength test was passed without incident However the device failed the component body test when the upper hole failed at approximately 85 kN This occurred where the metal is thinnest to the side of the upper hole In the dynamic test the device cut the rope sheath at forces comparable to the other devices between 46 kN and 64 kN 636 Petzl Croll chest Material Aluminium SheetWeight 132 gm Design principle Body loaded Method of use Chest ascender Figure 39 Petzl Croll Type B chest ascender Description The cam is identical to the one in the Petzl Ascension and is formed from cast steel The contact face of the cam is 32 mm long with a central vertical slot to assist the removal of mud from the rope and cam interface The face is covered with 26 teeth arranged in rows The axes of the teeth are angled downwards at an angle constant to the cam face ie they are not all parallel The teeth are short 1 mm longfairly sharp The catch is a sprung plastic lever with hollows within it for the finger and thumb There is a pressed stop in the body above the cam to help prevent the cam pulling through the channel when under extreme forces Markings stampedope channel outline of man indicating correct way up and characters to show rope diameter from 8 to 13 inclusive On the back of the body CE0197 EN567 a UIAA symbol and an 223224 instructions symbol outline of a in use The rope slot when the cam is open is not as wide as on the other devices however 105 mm rope is accepted easily Larger ropes may be more difficult It moves up and down the rope well although care must be taken when descending to ensure the sharp teeth do not snag the sheath When releasing the rope the plastic catch can be quite awkward to operate and ideally must be pinched between finger and thumb Test performance The Petzl Croll passed the minimum working strength test but failed the component body test The failure occurred when the metal surrounding the upper attachment hole fractured This occurred at 122 kN on the first test and 109 kN on the second The failure appeared to start at the pressed cam stop next to the upper hole In the dynamic tests it cut the sheath at impact forces between 47 kN and 6 kN 637 Summary At present most of the Type B ascender devices on the market have been designed for sport use whether for caving climbing or both As a result the designs are centred on producing lightweight products that are not really intended for intensive daily use in a working environment The exception here is the International Safety Components ISCder that would be ignored for sport use due to its excessive weight However in an industrial environment this is less of an issue and its bulky strength will be much appreciated by some users The usual damage scenario for handled ascenders is when they are bent over edges This can occur on a variety of scenarios some of which are fairly common For example at the top of a pitch when the parapet is reached The ascender is pushed so it lies across the edge and the operative then stands in the footloop This applies considerable force to the device where it is weakest between the cam and the handle The stamped aluminium devices are particularly prone to this although both the Camp Pilot and the Petzl Ascension have strengthening ridges in the most susceptible areas The ISC ascender would appear to be less vulnerable to this kind of damage Despite the differences in cam and body design the devices all performed well in use with little to choose between them Again the ISC device was the only one to stand out this was due to its blunt teeth allowing easy downward movement This could however mean it would perform less well on very dirty ropes not tested The only other obvious differences between the devices were the strength of the catch springs This affects the ease of removing the device and very strong springs can prove troublesome The obvious point not addressed by these tests is that of wear Devices will perform differently as they wear springs will weaken teeth will become blunted etc The only way to test this is by continuous use over long periods something which was not possible during this project Similarly device performance on worn or dirty ropes was not tested Both of these points are important when choosing an ascender and hence there may be scope for further work on these subjects At present users must rely on experience Most of the devices passed the static tests the only failures being the Kong Cam Clean and Petzl Croll chest ascenders On both of these the top hole failed at high forces during the component body test While high forces would not be applied to this hole during normal operations it is just about feasible during rescues It is not suggested that these devices are avoided on this basis alone but that manufacturers should perhaps address the problem in the next version of their device The Anthron chest ascender shows this is not too difficult to achieve In comparison with the other types of equipment ascenders are relatively weak This is because their strength when installed on the rope is limited by the strength of the rope sheath Because of this the devices should only be used for progression when only low single body weight static forces are applied They are not suitable for rescue loadings with two people Dynamic forces should be avoided in all situations Another point to consider is the markings on the devices While some are clear and useful others are at best vague Some would be useful here However some users do make the point that as the devices require training to use a trained user should know which way up to use them Similarly if used as part of a haul system the this way up markings become incorrect 64 TYPE C DESCENDER DEVICES 641 Introduction Type C devices are devices used for descending the rope They are commonly known as descenders The principle of these is fairly simple The rope is wound round a series of posts or bobbins which create sufficient friction such that under body load a controlled descent can be performed While countless designs exist not all are applicable to a working situation For the purposes of this project a descender was defined as A manually operated rope adjustment device which allows the user to achieve a controlled downward motion and to stop with hands off anywhere on the anchor line In addition these actions should not cause twisting of the rope The idea of this is to discount the many devices such as figureofeights and racks which are used widely in the sport world but are not as suitable for industrial use because they do not have an autolock facility They should also have a handsfree autolock or speed limiting function Autolocks come in two types single action and double action A single action autolock eg Petzl Stop Troll pro Allp techrequires a handle to be continuously squeezed to maintain descent If it is released the device stops or at least slows significantly This prevents an accident if the operator is knocked unconscious However in a situation where the user remains conscious the panic reflex is often to grip the device harder resulting in uncontrolled descent In the double action devices eg Anthron Double Stop Petzl ID etcent is also stopped if the handle is squeezed too hard preventing uncontrolled descent In practice the autolocks on some devices work far better than on others this is highlighted in the individual product reviews A third class of device has a function for continuously varying friction In the minimum friction position the device will not slip down the rope The applied friction is then steadily reduced by the user to allow descent at a set speed Descent continues at this speed unless the applied friction is adjusted by the user preventing the danger of a grab and drop Despite the name descenders are used for a variety of purposes in rope access The versatility of a descender will affect its suitability in the workplace as the fewer devices a worker has to carry the better One common secondary use for a descender is as a locking pulley while in conjunction with a handled ascender and footloop an effective work positioning system can be created using the descender for both ascent and descent The design of some devices makes them unsuitable for such secondary uses nevertheless these less adjustable devices may be more suitable for some rescue and escape purposes Seven devices were tested The variety of devices on the market means this can only be a representative sample However most types likely to be encountered by industrial users have been covered 642 Tests All devices underwent four tests as specified in prEN 12841 see 34 in this standardth only three devices undergoing the Descent performance test A Minimum working strength see section 446 prEN 12841 Hold 3 kN for 3 minutes This is a static test simply intended to check the devices ability to hold normal forces without slipping or distorting Although the weight of an operator is unlikely to exceed 100 kg sudden braking during descending or lowering will create larger forces This test gives a factor of safety of 3 to accommodate these forces The device must pass this test using only the manufacturers recommended lock whether by a cam action or with an additional rope lockB Minimum static strength see section 447 prEN 12841 Hold 6 kN for 3 minutes Again this is a simple test to check the devices ability to tolerate high forces without damage The figure of 6 kN gives a comfortable factor of safety for loadings that exceed the norm This test is aimed at testing the devices structural integrity rather than their resistance to slippage Hence for devices that do slip under such forces a knot is permitted below the device in order to allow the test It should be noted that this may impart forces into the device in a way not envisaged by the manufacturer but it is a credible situation for example when the device is halted by a knot in the rope C Dynamic performance see section 448 prEN 12841 Peak impact force and slippage with a fall factor 1 100 kg mass Although dynamic loadings on descenders may seem unlikely they are not impossible to achieve A likely situation would be a slip while clambering over a parapet wall Slowing fast descents quickly will also impose dynamictype forces on the device Neither of these situations is likely to produce falls greater than the length of rope deployed hence the fallfactor in the test is limited to 1 The results for this test were particularly interesting as they did not conform to the expected relationship between impact force and slippage See the Appendixt first it is difficult to reconcile a spread of results such as these with what is expected from the physics involved That is a reasonable linear relationship between impact forces and slippages This is clearly not the case here For identical test setups and similar resulting slippages the impact forces may vary from 2 kN to as high as 85 kN Examination of the charts produced by the recording instruments provides the answer Some devices produce a short rising curve followed by a flat peak maintained for up to half a second These devices are absorbing the energy steadily by slipping if only for a short distance without generating large peak forces Others show a long rising curve followed by a sharp peak maintained for as little as an eighth of a second Slight judders on the rising limb indicate slippage down the rope before the cam mechanism bites and arrests the fall suddenly The devices with the more aggressive cam actions eg Anthron Doublestop Petzl ID therefore achieved the highest impact forces The lowest impacts resulted from tests on the least aggressive devices eg Troll AllpD Descent performance see section 444 and 445 prEN 12841 This test was not conducted in accordance with prEN 12841 The standard requires that a 20 kg mass is supported by the device as the line is drawn through the device for 50 m In order to more accurately replicate the workplace the test was conducted with a 100 kg mass and the line was drawn through the device for at least 100 m Handling and heating when lowering a 100 kg mass for a 100 metres plus descent This test attempted to investigate the degree of heating of the devices as a result of friction during long drops A capstan was used to pull the rope upwards while the device was controlled so as to maintain it within the reach of the operator who was standing on the floor Using a probe the temperatures of the device and the rope were then taken at frequent intervals As the descent progressed the speed and degree of heating could then be assessed Due to the difficulties of temperature measurement and maintaining consistent descent rates test control was unsatisfactory The results are given for the three devices tested they are indicative only D Descender restraint force see section 443 prEN 12841 Although this test is specified in prEN 12841 in practice it was impossible to achieve consistent results that could be meaningfully compared The objective was to measure the force that must be applied on the free end of the rope to prevent descent of a 100 kg mass when the device is in its minimum friction position This force representsthe restraining force which has to be applied by the operator to the rope In practice it proved impossible to locate and maintain the minimum friction position on any of the devices This test may be practical when applied to simple nonautolock descenders It is not practical when the descenders in question are designed in differing ways to induce additional handson or handsoff friction In practice the variations between device designs and the difficulty in making a test setup meant the attempt was abandoned Most of the devices have some method of continuously varying friction making comparative results very difficult to achieve Of far more use although less quantifiable were the impressions of users who tested the devices on the ropesThe following table summarises the forces required to initiate sliding on the three ropes as deduced from 82A Minimum working strength tests Table 7 Force to initiate descent of descenders Force to initiate sliding under static load kN Device Beal Edelrid Marlow AML 3 28 3 Anthron AC30 6 6 6 Petzl ID 3 55 3 Petzl Stop 3 35 3 SRT Noworries 17 15 18 Troll Allp 19 19 19 Troll pro Allp tech 3 57 3 Figure 40 Type C Descending devices dynamic performance Note The plotted data are averages for the performance with each of the ropes kNSlip distance mPetzl Stop BealPetzl Stop EdelridPetzl ID BealPetzl ID EdelridPetzl ID MarlowTroll Pro Allp BealTroll Pro Allp EdelridTroll Pro Allp MarlowSRT No Worries BealSRT No Worries EdelridSRT No Worries MarlowML Descender BealML Descender EdelridML Descender Marlownthron Double Stop Bealnthron Double Stop Edelridnthron Double Stop MarlowTroll Allp Marlow643 AML Material Aluminium Weight 546 gm Design principle 3bobbin Autolock type Double action Figure 41 AML Type C descender Description A bight of rope is pushed between two steel posts and located around a capstan 57 mm in diameter The axle of the capstan is offset to create a cam action and a large handle 15 cm long 30 mm diameteris attached to the top This has two functions to stop the rope falling off the capstan and to progressively disable the cam action on the rope The handle has a thick plastic cover with pronounced finger ridges Markings Engraved on the back of the device are several batch numbers These are mostly covered by a large sticker provided with the device which has the following markings below the upper attachment hole TOP below that 223TO STOP LET GO OF HANDLE224 and below that AML 16682 BS EN 341 Performance in use Loading the rope is simple in principle but can be very awkward to do This is due to the tight slot between the capstan and the guide pin into which the rope must be forced Weighting the device automatically pulls the handle up into the stop position ready for descent Substantial effort is then required to pull the handle and initiate descent However the action is encouragingly progressive and quickly becomes familiar Overcoming the cam action of the capstan requires constant effort and releasing the handle quickly stops descent Due to the nature of the handle and its operation the panic grab scenario would be unlikely to apply to this device Nevertheless the device has a doubleaction autolock In use it was found the second part of the autolock was quite difficult to achieve requiring considerable physical effort and movement through a large arc The progressive action and tricky installation mean the device would be best suited to use in escape kits where it is preloaded on the rope for emergency use by novices Rescue use is also a possibility although the effort required to pull the handle when carrying a twoperson load might mean it is not ideal quW7Rsj performance In the minimum working strength test the AML held the force of 3 kN when installed on Beal or Marlow ropes but slipped on Edelrid rope It also passed the minimum static strength test of 6 kN without damage In the dynamic tests the AML produced some impressive results on the Beal and Marlow ropes due to its large rounded capstan and mild cam action On the softer Edelrid rope however slippage distances were high on one occasion hitting the buffer after 25 m of descent In the descent performance test it reached the highest temperature of any device the rope leaving the device after 140 metres was measured at 115644 Anthron Double Stop Material Aluminium with steel bobbins Weight 352 gm Design principle 2bobbin Autolock type Double action Figure 42 Anthron DSD25 Type C descender Description The body of the device is constructed from two stamped aluminium plates connected at the top by a smooth aluminium bobbin Halfway down the device there is a swivelling cast steel bollard arrangement around which the rope is threaded A long cast aluminium handle extends down the full length of the device on one side The side plates pinch together at the base where there is an attachment hole running through both plates Weighting the device pulls the bollards back into the body of the device trapping the rope against the top bobbin and pushing the handle out Squeezing the handle pushes the bollard arrangement out reducing friction and allowing descent Further squeezing then begins to trap the rope between the handle and bollard increasing friction and halting descent in use In use the device is quite awkward to load and does not allow movement up the rope However the length and design of the handle allows extremely fine control of the friction applied The action of reducing and then increasing friction occurs in a very smooth and progressive manner Maintaining a constant descent rate requires the handle to be constantly squeezed to the central position During descent releasing the handle immediately halts descent Likewise any oversqueezing of the handle immediately slows or stops the descent The design is very userfriendly except for loading and very safe Even a beginner would be unlikely to have trouble descending with this device For these reasons it would be ideal for use in escape kits The inability to move up the rope however limits its applicability to rope access With large eg rescueforces the second part of the autolock works less well requiring considerable force to trap the rope and slow descent However the first part of the autolock is unaffected Markings On the front of the device a fairly clear loading diagram with the top rope clearly shown ending at an anchorage with the word UP ROPESSEIL 9 12 mm CE0123 On the rear of the device the loading diagram is repeated in the correctly for the rear of the device reversed orientation A instructions symbol is accompanied by the words PROPER TRAINING IS ESSENTIAL BEFORE USE Test performance In the static tests the unique cam design proved to be very efficient It was the only descender to hold the minimum static strength force of 6 kN without any additional lock relying purely on the cam action of the bollard arrangement This unwillingness to slip was reflected in the dynamic tests where the Anthron Doublestop produced the highest impact forces of any descender 85 kNIn the descent performance test the Doublestop performed quite well achieving a peak temperature of 85C even after 140 metres of descent 645 Petzl ID Material Aluminium body steel bobbin plastic handle Weight 534 gm Design principle 1bobbin Autolock type Double action Figure 43 Petzl ID Type C descender Description From the outside the ID consists of two pressed aluminium plates with a large plastic handle attached The plates are pinched together at the base where an attachment hole passes through them both The rear plate acts as the main frame and has several components mounted on it The front plate acts as a cover for the device and swivels aside to allow installation of the rope Its attachment hole has a catch to allow access to place the rope without detaching the device from the main frame Inside the device are four main components At the top is a steel anvil against which the rope is trapped by a large cast steel bobbin below it This bobbin is mounted on an axle and can rotate through about 30 The top section of the bobbin is cut away to create a slot between the bobbin and the anvil and to create a cam action when the bobbin is rotated clockwise When the device is weighted this cam motion occurs due to the friction of the rope running around the bobbin The lower part of the cam is cut away to accommodate a fixed steel pin 10 mm in diameter around which the rope also runs This pin extends out of the rear of the device and forms an axle for the large plastic handle This is attached to the main bobbin by a clutch mechanism rotation of the handle turns the bobbin clockwise squeezing the rope against the anvil in a stepwise motion This operation is used to lock off the device Anticlockwise rotation of the handle when the device is weighted progressively releases the cam action of the bobbin However this only occurs up to about the 9 oclock position Beyond this the handle disengages and the force from rope friction rotates the bobbin trapping the rope and stopping descent This is to prevent the panicgrab and drop scenario Between the bobbin and the attachment hole is a small toothed cam This is positioned purely to trap the rope should the device be installed upside down This is the most complex device tested and the exact operation of the clutch mechanism cannot be seen without destroying the device Performance in use In use the device is simple to install onto the rope the handle must be in the unlocked position Movement up the rope is easy allowing slack rope to be easily taken in A positive lock is then easily achieved by turning the handle clockwise Alternatively weighting the device in a confident manner immediately engages the stop action A more tentative approach will not always have the same effect although this can be avoided by engaging the lock Turning the handle anticlockwise meets resistance between the 10 oclock and 11 oclock positions Movement beyond this steadily releases the cam allowing the speed of descent to be controlled Movement beyond about the 9 oclock position disengages the clutch and the cam is free to lock At first this action can be very frustrating as the panic lock is very easy to trigger However practice allows any rate of descent to be maintained Markings On the front of the device is a line diagram showing the device closed and the rope installed The lower rope is held by a hand the upper forms a loop There is also an instructions symbol Inside the device the loop and hand symbols are repeated at the ends of the rope channel On the top of the main bobbin are characters showing rope diameters from 10 to 115 inclusive On the back of the device is CE0197 EN 341 TYPE A MAX 150Kg200m Test performance The ID passed both of the static hold tests Although the ID features a large cam similar in dimensions to the AML descender the cam action is quite severe and gave some high impact forces in the dynamic tests These ranged from 53 kN to 78 kN again dependent on the rope used The ID produced very good results in the descent performance test The ID maintained a significantly lower temperature 70C than the other descenders even after a drop of 200 metres 646 Petzl Stop Material Aluminium Weight 324 gm Design principle 2bobbin Autolock type Single action Figure 44 Petzl Stop Type C descender Description The Stop is of fairly simple design consisting of two similarly sized bobbins around which the rope snakes in an S fashion The lower bobbin has a cam action driven by the friction of the rope on the cam Two stamped aluminium plates form the sides of the device The rear plate has a closed attachment hole and forms the main frame of the device The front plate pivots around the axle of the lower bobbin to allow access to the interior This plate has an open attachment hole closed by a plastic catch which allows the rope to be installed without unclipping the device from the harness The lower bobbin is made from cast steel and has an attached aluminium handle 10 cm long used to disable the cam action The upper fixed bobbin is aluminium but has a steel wear pin at the point where the rope is pinched by the cam action At the top the device is closed by a steel post 7 mm in diameter This can also be used to generate additional friction by looping the rope back over it Performance in use Installing the device on the rope is relatively simple the side plate is swung open and the rope is wound round the bobbins The side plate then swings shut and the catch clicks shut over the attachment karabiner Movement up the rope is possible allowing slack rope to be taken in The device should then be locked off before weighting This is achieved by passing a bight through the attachment karabiner and then around the top of the device forming a half hitch When weighted this will prevent rope creeping through the stop mechanism and guard against accidental release if the handle is knocked To initiate descent the rope is unwound and held in the braking hand The other hand then squeezes the handle to release the cam The correct technique is to release the cam fully and control descent with the braking hand rather than with the cam This is a single autolock no provision is made against the 221panic grab and drop222 event Ascending the rope is possible though not easy and it also functions well as a locking pulley when halfthreaded nRlCmZDSeD2BH4 bA performance The static tests were passed without deformation to the device A simple halfhitch rope lock was required to stop slippage Rather worryingly for such a popular device it was the only device to cause rope damage in the dynamic tests Although impact forces were no higher than with other devices the rope snagged between the side plate and bobbin severing the sheath Following this the rope could not be removed and the device could not be reused 647 SRT NoWorries Material Aluminium with steel bobbins Weight 820 gm Design principle 3bobbin Autolock type Double action with disable screw Figure 45 SRT Noworries Type C descender Description The SRT Noworries has three steel bollards around which the rope follows a sideways shaped path The middle bollard is slightly smaller and pivots out of the device to allow loading of the rope The pivot is located at the base of the device and acts as the attachment post The pivot also allows the middle bollard to pull into the device when loaded when increased friction effects an autolock To overcome this a handle is fitted which pushes it outwards reducing friction and allowing descent The edge of the plate is shaped such that pulling the handle beyond a certain point no longer pushes it outwards allowing the plate to move back in Further downward movement of the handle actively pulls the plate back in This doubleaction autolock can be disabled at any point by tightening a wingnut which locks the handle in position The idea of this is to allow handsoff descent at a constant rate in use Installation on the rope is fairly simple A small catch releases the middle bollard and plate which then swings open It is not sprung so does not need to be held open Movement up the rope is possible but not easy On 105 mm rope the device is quite fast only a small amount of handle movement is required to initiate descent The handle position is basically vertical and can be a little awkward Pulling the handle too far results in movement through an arc where there is very little friction imparted to the rope before the second part of the autolock is reached this can result in a fast descent To return to descent the handle must be pushed back up again the handle is in a slightly awkward position The handle is returned to the upper position by reversing the above procedure again this must be done quickly to prevent a sudden drop as the friction decreases Movement up the rope is difficult although possible and the instructions show the device being used for belaying and as a locking pulley Markings on the front of the device a loading diagram with UP marked adjacent to the rope leading to the anchor and a hand holding the free end of the rope A safe working load of 300 kg is marked and MAX 2000KG STOP and GO are marked in the appropriate positions around the locking key slot There is no CE mark Since the sample was obtained for the tests it is understood that this device is now supplied with the CE mark Test performance The static tests were passed without deformation however an additional ropelock halfhitch around body was required as recommended in the instructions to stop slippage The dynamic tests produced a somewhat inconsistent spread of results again they were closely related to rope type On the stiff Marlow rope results were excellent but on the Beal and Edelrid ropes less friction was created and the device slipped long distances before arresting the fall 648 Troll Allp Material Aluminium Weight 318 gm Design principle 3bobbin Autolock type Screw type Figure 46 Troll Allp Type C descender Description The rope follows a sideways 221222 shaped path around three bollards When loaded rope friction pulls the middle bollard between the other two generating friction and preventing movement This action is overcome with a winged bolt arrangement that pushes them apart A spring mounted on the attachment post pulls the bollards together when the device is not weighted A sprung catch is mounted on the front plate and engages in a slot on the rear plate this prevents accidental opening Performance in use Installing the rope can be difficult one hand is required to stop the side plates springing back together while the other loads the rope making sure it does not catch in the slots in the side plates At this point the bolt should be screwed out as far as possible When the device is weighted the bollards then pull together preventing descent Screwing the bolt in then slowly pushes the bollards apart and descent begins Little effort is required to turn the bolt although the lefthanded thread feels unfamiliar However it gives very fine control and handsoff descent is possible although speed will increase due to the progressive reduction of the weight of rope below the device This can be overcome by keeping the rope in a bag this is then slung from the operator222s harness Screwing the bolt out has the opposite effect slowing descent When the bolt is screwed out completely the device is in the stop position there is no additional lock Ascending the rope is difficult but possible being easier if the device is kept tight on the rope rather than allowing slack above Markings The front of the device shows a simple loading diagram Stickers are mounted on either side of the key to indicate which direction to turn it red S and green G bWq8Mxh1hTest performance The Troll Allp passed the minimum working strength test of 3 kN but after 3 minutes holding a force of 6 kN the device was severely distorted and unusable The cam action of the device was not sufficient to prevent slippage at the higher force and a knot had to be tied below the deviceThe Allp did not perform well in the dynamic tests Although the stiffer Marlow rope gave some reasonable results On the Beal and Edelrid ropes the device failed to arrest the fall and the device hit the buffers at the base of the test rig 649 Troll pro Allp tech Material Aluminium with steel bobbins Weight 598 gm Design principle 3bobbin Autolock type Single action variable friction Figure 47 Troll pro Allp tech Type C descender Description This is Trolls second generation descender and is a development of the Allp As with the original it has three bobbins around which the rope follows a sideways 221222 shaped path The design is similar to the original Allp although the top and bottom bobbins are much reduced in size being steel posts 12 mm in diameter The central bobbin is now steel and has a sprung cam action A solid aluminium handle is attached to release this action The bolt is now hidden within the device and a winged closed nut is used to screw it in and out The side plates remain aluminium but are larger and the overall impression is of a larger more solid and more refined device The addition of cam properties to the central bobbin means there are now several ways to control descent Firstly the cam and handle can be ignored and descent controlled solely with the bolt as with the original Allp the bolt can first be adjusted for the users weight and rope type and then the handle can be used as a single autolock squeeze to go release to stop Thirdly both methods can be used together to allow varying friction over long drops or for various work purposes The variable friction does not however completely remove the need for the user to maintain control on the rope below the device with their braking hand There is no double action autolock but the variety of control methods and the variable friction markedly lessen the chances of one being required Having said this in inexperienced hands a panic grab and drop is possible Performance in use Once accustomed to the technique it is fairly simple to install on the rope and will allow ascent The choice of control methods means the operator needs practice in order to establish the best method for himher This will come with experience of using the device None of the control methods are difficult to learn The variety of control methods does however mean that mistakes can be made in a variety of ways training as with all devices is essential Test performance The pro Allp tech passed the static tests without damage Despite its similarities to the Allp and the Noworries the pro Allp techs cam bobbin means that it performs differently in a dynamic situation Excellent consistent results were obtained on Beal and Edelrid ropes although with Marlow rope peak impact forces were a little higher Slippages on all tests were consistently low 6410 Descenders Summary As with ascenders the method of use for all of the descenders is fairly standard so the tests give easily comparable results Only two gave cause for concern the Petzl Stop under dynamic loading and the Troll Allp which failed the 6 kN hold test It is worth noting that these are old designs in both cases the manufacturers have developed new generation devices specifically for the industrial market and these performed well A move by industrial users to use the newer devices from these manufacturers is to be recommended All the other devices performed well in the applied tests For rope access selection must be based on good test performance plus ease of use versatility and resistance to wear It should be noted that all these devices required the operator to impart control during descent to a greater or lesser degree with the braking hand on the free rope For escape kits the devices will be used at most occasionally and the resistance to wear is not so important What is more important for these is a progressive action and double autolock to maximise safety for unfamiliar users For rescue kits the needs are different again the primary concern being that control can be easily maintained even with large loads This allows sudden shock loads to be avoided and thus increases safety 7 ATTACHMENT LANYARDS Cows tails71 INTRODUCTION Cows tails are short lanyards used to connect the harness either to anchors or to rope clamps They are deployed to allow the user to maintain two points of connection to hisher harness at all times Operatives usually carry several cows tails At one end they are linked directly to the harness belay loop or screwlink connector at the other they are linked into a karabiner that can then be used to clip into various anchors or rope adjustment devices For effectiveness the lengths of cows tails need to be adjusted precisely to the users height and arm length For this reason they are customarily constructed from lengths of rope with knotted terminations Proprietary sewn cows tails are available but only in fixed lengths which may or may not suit the users size or technique Cows tails are subject to heavy use It is imperative that they are withdrawn from use as soon as any damage or significant wear is apparent In this respect the operative will more readily retire cows tails made from knotted rope as they are cheaper than proprietary cows tails It is possible for cows tails to be clipped to anchors or devices below the harness attachment point This makes fall factor 2 falls possible and therefore cows tails must have good shockload absorbing qualities If the user is aid climbing the cows tails will be the sole component If the cows tail is being used solely with a backup device it need not be energy absorbing as the device should absorb the energy by slipping The main variation in cows tails is the knots used to tie them Ideally these are of low bulk with some energy absorbing abilities 72 METHODS A dynamic test was used to examine how different cows tails perform in a fall situation The dynamic test applied was to drop a 100 kg mass through a distance equal to twice the length of the cows tails ie a factor 2 fall Four different types were tested Petzl sewn dynamic rope Beal 11 mm Apollo knotted dynamic rope Beal 11 mm Apollo knotted lowstretch rope Beal 105 mm Antipodesand knotted tape Beal 26 mm flatfore tensioning all were approximately 60 cm in length or 5 cm Three different knots were tested overhand figureofeight and barrel double fishermanshe tape was tied with a tape knot Prior to the tests all knots were pretightened with a 2 kN force held for 20 seconds The maximum impact force was then recorded for each test Each test was repeated three times The results are displayed below The limit of the measuring equipment was 10 kN off scale indicates forces above this On some tests those which failed to record the peak impact force existed for too short a time for the equipment to record Table 8 Impact forces from lanyards with 100 kg mass factor 2 fall Material force kN Impact force kN Impact force kN Average Impact force kN Overhand 714 694 710 706 Figureof8 665 662 748 690 Dynamic rope Barrel 633 633 630 632 Overhand 10 10 10 10 Figureof8 873 915 940 909 Low stretch Barrel 873 889 No record 881 26 mm tape Tape knot brokeBroke but no record Petzl Jane dynamic ropeSewn 10 10 10 10 73 KNOTTED ROPE COWS TAILS In all tests unsurprisingly the dynamic rope gave lower forces than the low stretch rope On the low stretch rope considerable variation was found between different knots Overhand knots produced a reading beyond the range of the measuring equipment this was estimated from the graph to be 12 kN Figureofeight knots performed considerably better with impact forces of averaging 9 kN The Barrel knots performed slightly better again giving impact forces just below 9 kN With the dynamic rope the pattern was repeated although the variations between the knots were less marked The overhand knots gave consistent impacts of 70 kN to 72 kN while the figureofeight results were slightly wider at 67 kN to 76 kN The Barrel knots performed extremely well delivering consistently low impact forces of 63 kN to 64 kN The graphs produced during the tests show the steady tightening of the knots particularly on the Barrel knot where the initial upward trace shows a steadily lessening gradient as energy is absorbed With all the knots tested extreme tightening occurs during the impact this would be obvious on inspection and in the workplace the cows tail should be replaced immediately 74 PETZL JANE SEWN TERMINATION COWS TAILS These readymade cows tails feature a short length of dynamic rope with loops sewn into each end A variety of lengths is available the 60 cm version was used for the test Although made from dynamic rope the Janes created high impact forces These forces could not be measured they were outside the range of the recording equipment They were estimated to be of the order of 10 kN to 11 kN Following the tests it was impossible to tell if they had been subject to a fall despite the fact that after a fall of this severity the lanyard should be retired immediately 75 KNOTTED TAPE COWS TAILS Beal 26 mm flat polyamide tape was used for the test 60 cm lanyards were made up with a double overhand loop tied at each end These cows tails simply broke at the knot under the test conditions On the first test the recorded force was 87 kN On the second test the machine did not record a peak the force existed for too short a duration Under static loading the knotted tape cows tails breaking force was measured as 10 kN The ultimate breaking force of the tape is approximately 15 kN thus the knot reduces strength by about a thirdClearly tape slings of this type ie tape with knots is an unsuitable material for this purpose as its static nature and weak knot strength will not absorb dynamic forces There is scope to conduct tests on cows tails made from tape slings which have been sewn down their length to form lanyards with a small loop at each end for a connector 76 COWS TAILS SUMMARY The tests show that the best material for cows tails is knotted dynamic rope Of the knots tested the Barrel knot produced the lowest impact forces followed by the figureofeight As well as having the benefits of easy adaptation to the user it is currently the only way in which acceptable impact forces can be achieved All the knotted dynamic rope cows tails produced impact forces between 63 kN and 76 kN perhaps a little higher than ideal but much better than any alternative In practice forces are likely to be lower as the harness and body will also play a part in energy absorption Knotted tape cows tails cannot be recommended for use where any dynamic loading is possible There are sewn termination rope cows tails on the market made from both dynamic and static rope while these may be applicable to low fall factor situations neither are suitable for use as cows tails Sewn dynamic rope cows tails should be restricted to uses where the maximum possible fall is fall factor 1 Sewn cows tails made of low stretch rope are not recommended for any dynamic loading situations Static rope tied with overhand knots gives a high force However with figureofeight or barrel knot double fishermans the impact forces are lower 9 kN This figure is too high to recommend for use but it is interesting to note that it might prove useful in an emergency 82 8 LANYARDS FALL ARREST81 INTRODUCTION Lanyards are commonly used in fall arrest situations and have mostly been developed purely for industrial use However the Charlet Moser energy absorber block has been designed for ice climbing All the types tested consisted of an unit with a progressive tearing and extending action to lessen the impact force of a fall Most utilise tear webbing which is designed to commence tearing above a certain load This tearing action absorbs energy An alternative design utilises the tearing of stitching to absorb energy The short energy absorbing blocks are extended to the working length required with a lanyard of rope or tape Others are complete units supplied in a finished state One end is then attached to either a dorsal or sternal attachment point on the harness while the other is supplied with a connector to attach the user to the anchor point The industrial standard BS EN 355 states that the maximum length of the lanyard including connectors is 2 metres The lanyards were primarily tested for their dynamic performance under fall factor 2 conditions with a 100 kg mass The tests were carried out using the catch plate rig at Petzl See section 1445 in the Appendix for details The latter requires the use of a As fall arrest lanyards are permitted to be up to two metres long this involved a total drop of 4 metres a realistic but exacting test This test is in accordance with the BS EN 355 The standard also states two additional points the energy absorbing block should withstand a static force of 2 kN without deployment and the maximum braking force should not exceed 6 kN when tested with a rigid mass On one test this maximum was exceeded by 1 kN but only for less than 1100 second It can be argued that such a force acting for this short time would not be damaging to the operative especially as their harness will absorb some of the energy thereby reducing the force on the body The maximum lanyard extension allowed in a fall is 175 m Assuming that after a fall the distance from the harness connection point to the underside of the operatives feet is 2 m then adding this distance the lanyard length and the lanyard extension gives 575 m This last dimension is the minimum safe height for the anchor point to be above the ground The graphs produced by the chart recorder give a critical insight into the manner in which the different blocks absorb energy Seven different lanyards from six manufacturers were tested dynamically Six different lanyards from six manufacturers were also tested on the Lyon long pull rig The force to initiate tearing the peak force achieved during tearing and the final breaking force were recorded Each test was repeated twice This test allowed visual appraisal of the energy absorption at a speed low enough for the human eye to appreciate The conditions however are not as realistic as in the dynamic test and the results must be considered less credible than those from the dynamic tests The limited length of the long pull rig prevented full deployment of all of the lanyards Comparison of the two sets of test results shows the value of the dynamic test See Appendix 7 for the results BRITISH STANDARDS INSTITUTION BS EN 355 1993 Personal protection equipment against falls from a height Energy absorbers82 BEAL BEP ENERGY ABSORBER Length 02 m Principle Tear webbing 48 Beal energy absorber block shown removed from protective sleeve Description The BEP consists of a small 160 x 30 x 40 mm of white tear webbing Clear shrink sleeve allows easy visual inspection of the block It appears to be identical to both the Petzl Absorbica and the MillerDalloz block differing only in the labelling Test performance It was tested under the dynamic test conditions Results differed slightly from the Miller energy absorbing block the graph trace had sharper peaks This can be attributed to two factors firstly the BEP being a component energy absorber rather than a complete lanyard with energy absorber was subjected to the maximum drop of 4 metres by the test weight onto the catch plate Secondly the Miller blocks attached lanyard will have stretched to some extent absorbing energy and thus reducing the peak force On the tests performed on the BEP individual peaks just exceeded 6 kN by less than 1 kNd only for a single peak approximately 1100 second It is suggested that this is not significant enough to warrant a failure 83 BH SALA Length 2 m Principle Tear webbing Complete lanyard with energy absorber Figure 49 BH Sala zorba with rope lanyard Description Two different lanyards were obtained from BH Sala both confusingly called Zorba They both included similar energy absorbing blocks of 45 mm wide white tear webbing However one had a rope lanyard attached while the other had both a tape lanyard and an additional tape loop This loop takes the load should the energy absorber section be fully deployed They both have similar tear webbing and performed in a very similar manner Test performance In the drop test they performed well with graph traces showing smooth deployment without exceeding 6 kN However on one test the lanyard deployed fully indicating there is little margin for safety beyond the standard 84 CHARLET MOSER Length 012 m Principle Tear stitching Component Figure 50 Charlet Moser shock absorber shown complete at the top extended at the This small block was originally designed for ice climbing to limit the forces imposed on screwin ice protection during a fall As such it is only certified to the mountaineering standard for use as a sling However it does have applications in industry where its small size is attractive To justify the use of this unit which is only certified as a none energy absorbing sling the user must carry out a hazard identification and risk assessment in order to show that use of this unit is appropriate in the workplaceTest performance Unlike most of the other devices it operates by progressive breaking of a stitch pattern rather than tear webbing It has a smooth arrest pattern However its overall energy absorbing abilities are much less than the larger industrial devices With a 100 kg mass the maximum fall arrested safely was 05 metre with a force of 33 kN Falls of 1 metre or more resulted in complete deployment with a large final peak force With a 1 metre fall the peak force was 75 kN The fall distances quoted were the height that the mass dropped before it engaged the catch plate on the test rig 85 PAMMENTER PETRIE P P Length 2 m Principle Tear stitching Complete lanyard with energy absorber Figure 51 Pammenter Petrie NRG lanyard shown after Three identical lanyards were obtained from P P complete with captive steel karabiners The lanyards consisted of a single 34 m length of tape part of which is folded and sewn as an energy absorber The stitching pattern in contrast with the Charlet Moser device appeared fairly coarse Before deployment the total length including connectors was two metres Test performance In the dynamic test the graphs showed some cause for concern The traces showed wide ranging peaks and troughs indicating jerky deployment On the first test a peak value of 84 kN was seen However this only represented a single peak value of short duration A final rounded peak was seen as the stitching stopped tearing when the energy absorbing element reached full deployment and the load was restrained by the lanyard This was far more marked on the PP lanyard than any other86 PETZL ABSORBICA Length 02 m Principle Tear webbing Component Description Outwardly identical to the Beal BEP and MillerDalloz block except for the labelling the Absorbica performs in a similar fashion Test performance To avoid duplication the Petzl block was tested in the static pull test rig while the BEP block was tested in the dynamic drop test rig at Petzl In the static pull the deployment appeared to be very jerky with high peak forces of up to 85 kN Peak forces were lower in the dynamic test 87 PETZL ABSORBICA I Length 08 m Principle Tear webbing Complete lanyard with energy absorber Figure 52 Petzl Absorbica I shown with energy absorbing section removed from its sleeve lanyard comes as a complete unit and is available in several versions as a simple lanyard as a Y lanyard and with or without connectors The simplest version was tested at 80 cm it was the shortest complete lanyard tested The Absorbica I consists of a tape sling sewn into a closed loop of tear webbing The tear webbing is protected by an elastic sock which can easily be removed to allow inspection of the energy absorber section Test performance In the drop test it performed well with a steadily increasing force There were no large peaks or troughs indicating consistent tearing and the three tests produced results ranging from 472 kN to 523 kN 88 MILLER DALLOZ Length 12 m Principle Tear webbing Complete lanyard with energy absorber Figure 53 MillerDalloz lanyard shown with the energy absorbing section removed from its sleeve Description The energy absorbing part of this lanyard appears to be identical to the BEPAbsorbica this time with a sewn tape lanyard attached Test performance This gave good results in the dynamic test The drop was arrested without any large peak forces and showed consistent results between tests The block did not fully deploy indicating a considerable safety margin Maximum force was 527 kN 89 SPANSET Length 2 m Principle Tear webbing Complete lanyard with energy absorber Figure 54 Spanset energy absorbing lanyard Description The Spanset lanyard consists of a lanyard and block arrangement similar to the other lanyards However the entire assembly is protected by a tough covering layer This consists of heavyduty heatshrink on the block and a plasticized tape tube over the remainder This adds to the weight and bulk of the lanyard but will give resistance to damage Test performance Results from the drop test were excellent The block deployed at a very consistent force of 4 kN The graph trace shows fewer force variations during the energy absorption than on any other test The element did not deploy fully leaving a substantial safety margin 810 LANYARDS CONCLUSIONS Fall arrest lanyards are subject to the standard BS EN 355 and the research did not produce any surprising results The lanyards all arrested the drops safely the prime concern being over margins of safety The major concern with lanyards is not performance when new but longevity All the lanyards tested were constructed all or partly from polyamide tape a material that is particularly susceptible to weakening as a result of abrasion The likelihood of contaminants such as paint reaching the load bearing material is also high Only one of the lanyards tested from Spanset had any form of abrasion protection Ideally all lanyards would include this kind of protection Lanyards are routinely subject to high levels of wear and tear In rope access operatives are constantly in suspension and therefore very attentive of the state of their equipment In fall arrest situations the lanyard is often seen as a hindrance rather than a help and is very rarely called into use As a result operatives are unlikely to pay special care to their lanyard Any protective covering is therefore extremely useful However even the Spanset lanyard which was otherwise well protected neglected to protect the tape where it rounds the connecter This is the point where potentially wear will be greatest 90 9 PRUSIK KNOTS 91 INTRODUCTION Prusik knots are tied around the working rope using a supple rope or cord whose diameter is preferably smaller than that of the working rope They are designed to grip the working rope when loaded but slide when unloaded They are widely used by both rescue teams and particularly in the United States of America Within rope access they are not widely used and as a result there is little consensus on which knot should be used for what purpose This is partly due to the variety of suitable knots and partly due to the variations in performance due to rope types Just as there is no standard working rope there is no standard rope for tying prusik knots The resulting permutations possible from these variables mean that it is very difficult to predict how a knot will perform Most users have to gain this knowledge from experience The following tests simply serve to illustrate how under static loads different knots behave on different ropes The different types of knots have slightly different properties and hence different knots are preferred in different situations Similarly different ropes tend to be preferred for different knots The five knots tested were those used by respondents to the questionnaire 92 TESTS Five different knots were tested using three diameters of working rope and two types of prusik rope In addition one of the working ropes was obtained and tested in both a new and a worn state Most prusik knots are tied with a closed sling of rope prusik looprather than a rope end The Blake knot is the only exception to this Kernmantel and hawser laid suspension ropes were tested Polyamide from Edelrid and polyester from Beal for the kernmantel ropes The hawser laid rope was made from polyamide The material used for the knots was 10 mm diameter Prusik Regate made from polyester and 6 mm accessory cord both made by Beal The knots were subjected to a static test to determine the force that they would hold without slipping The test was limited to 4 kN knots which reached this force without slippage then had to hold it for 2 minutes to detect creeping The results can only be taken as a guide however as many factors can affect their performance The age and state of both the working rope and the prusik rope are very important brand new rope may not grip as well as older rope that has been worn in and lost some of its sheen Slight differences in tying and setting the knot will affect how readily the knot grips the rope when first and subsequently loaded Similarly varying the diameters of both working rope and prusik rope will affect performance 93 BACHMANN KNOT Figure 55 Bachman knot tied with 6 mm accessory cord This knot is different from the others in that it is tied around the back bar of a karabiner as well as the rope In the tests an offset D 12 mm steel industrial karabiner was used The karabiner is not used as a handle and will cause the knot to slip if it is weighted The knots advantage is that it does not jam and extra friction can be easily added It held the 4 kN force on all the ropes when tied with 6 mm accessory cord When tied with 10 mm Prusik Regate rope on kernmantel ropes it slipped on 105 mm between 06 kN and 10 kN and on 135 mm between 16 kN and 19 kN but held the 4 kN force on the hawserlaid 12 mm rope 94 BLAKE KNOT Figure 56 Blake knot tied with Prusik Regate 100 mm rope The Blake knot is the preferred knot amongst In contrast with the other knots it is tied with a rope end rather than a loop It was the only knot tested to hold the 4 kN force for all test combinations With the thicker 10 mm Prusik Regate rope it released easily When tied in the thinner 6 mm accessory cord it was a little more difficult to release 95 FRENCH PRUSIK Figure 57 French prusik knot tied with 6 mm accessory cord The French prusik is one of the simplest prusik knots its main advantage being that it will release under load In all the tests it was very easy to release after the load was removed It was able to hold higher forces when used on the thicker 12 mm and 13 mm ropes On the 105 mm rope it slipped at 05 kN when using 10 mm Prusik Regate rope and at 13 kN on the thinner 6 mm accessory 96 KLEIMHEIST KNOT Figure 58 Kleimheist knot tied with 6 mm accessory cord Popular in climbing circles the Kleimheist is another fairly simple knot The knot was tied using a sling made of 6 mm accessory cord This was wrapped around the rope two or three times and then back through itself to create a type of helical knot When tied in the thicker 10 mm Prusik Regate rope it slipped on all the ropes at forces below 05 kN In contrast when tied with 6 mm accessory cord it held the 4 kN force on all the ropes 97 PRUSIK KNOT Figure 59 Prusik knot tied with 6 mm accessory cord The prusik knot is the original and best known ascender knot It is based on a Larks foot but with extra turns It held the force on all but one test Tied with the 10 mm Prusik Regate rope the knot slipped at 05 kN when tested on the 105 mm rope 98 SUMMARY Prusik knots clearly work Some are better suited to holding large loads while others are more suitable when an easy release is required The combination of main rope and prusik rope is critical to how the knot will behave Even with the limited variety tested significant differences are seen between the combinations Great experience would be required to predict the behaviour of any combination It would be more realistic to adopt one knot and rope combination and experience its behaviour until its performance in different situations can be assured For most situations in rope access a device would be available which would perform in a predictable fashion Prusik knots are probably best suited to nonPPE applications such as hauling and suspending equipment There is much scope for further work on prusik knots A study into their behaviour under dynamic loads would be particularly interesting as concerns are often raised about melting due to friction when the knot slides under heavy loading 10 CONCLUSIONS 101 GENERAL CONCLUSIONS AND COMMENT The summaries and conclusions given in each section of the report will not be repeated here What follows is a final overview This project has been conducted during a period of rapid development in both techniques and equipment for work at height Many of the rope adjustment devices which were tested may already have been superseded by subsequent models Exceptions to this are ropes which currently and for the last decade have been the least changing element in rope access systems The elasticity that polyamide ropes provide dynamic ropes where falls from above anchor point are possible low stretch ropes where only falls from below the anchor point are possible is a major key to limiting loads experienced by the operative to safe levels While they remain the core element in rope access all other system components will be designed around them The standard BS EN 1891 was specifically drafted to include lowstretch ropes suitable for rope access and provides a secure and appropriate basis for buying and deploying ropes appropriate for rope access and arboriculture The Standard BS EN 892 is designated for dynamic mountaineering ropes It is also appropriate for work applications involving potential fall factor 2 drops The ability to tie knots to form terminations anywhere along a rope is of key importance to the practicality and versatility of rope access and work positioning systems The tests performed on knot strength demonstrate that there are a number of knots which give appropriate security and which can be used with confidence Existing standards for rope adjustment devices come from different backgrounds and are unsatisfactory It is to be hoped that prEN 12841 will now be processed and completed as speedily as possible and that devices used in rope access for ascent descent and backup security will subsequently be tested and certified to this Standard Protection of rope against the effects of abrasion over harder surfaces is essential Ideally this should be achieved by rigging to avoid any such abrasion Failing that rollers remove all risk provided that the rope remains in place on the rollers However they are not applicable to all situations and where a textile protector has to be deployed of the types tested canvas achieved clear superiority over others Future development could involve the deployment of static ropes with the introduction of dynamic load absorbers at every anchor point This could radically alter the ropes which might be used and that in turn could radically alter the adjustment devices used in conjunction with the ropes This is not likely to occur for at least a decade if ever but it is important that the path to radical change is not closed by an over rigid adherence to existing ways of working The advantages of rope access and similar work systems do not derive from the equipment employed alone The motive force for the system is provided by the operative The worker and hisher equipment combine to form a machine This machine only functions as well as the sum of its parts The ropes and devices are essentially passive the dynamic element is provided by the workers strength and skills The worker is required to have the intelligence as well as the strength to work in this way It follows that this method of working requires rigorous training practice and assessment before the equipment investigated can be used effectively and safely The words for use by trained operatives only could well be added to the comment on every item of equipment featured in this report98 11 FUTURE WORK This study has highlighted a number of areas which merit further investigation A study of the effects of increase in the sheath mass of ropes on the performance of rope adjustment devices B A study of the effects of rope wear on the performance of rope adjustment devices A study into the abilities of more complex knots such as the double figureofeight on a bight and the alpine butterfly Further investigation into the effect of contaminants particularly rust and bird droppings on rope strength A study into the effects of tightening due to use on the abilities of knots used in cows tails F An investigation into the effects of both knotting and wear on the strength of the webbing components used in rope access G A study into the abilities of prusik knots to absorb dynamic forces H Measurement of the forces generated when carrying out a snatch rescue A study into the protection of the rope from abrasion by different types of carpet A study into the abrasion of ropes when running over different types of edge eg scaffold tubes K A study into the effect on ropes from side to side movement across an edge 100 12 APPENDICES 102 121 APPENDIX 1 PERSONNEL INVOLVED IN THE PROJECT The testing was carried out by Lyon Equipment staff supported by staff from Beal rope manufacturer Petzl equipment manufacturer and the Leeds University School of Textile Industries when the facilities of these establishments were used This report was made possible by their cooperation The report was written by Lyon Equipment staffAdam Long BSc HonsRATA level 1 Malcolm Lyon BSc Chairman IRATA Health Safety and Equipment Committee Graham Lyon BAOpen MICE MIQA Support to the test programme and the writing of the report was provided by Dave Brook BSc MSc Research Fellow Leeds University School of Textile Industries Fred Hus Managing Director of Aak AS Norway and Convenor of Seddon Consultant for interpretation of European StandardsPhil Tate Metallurgist and consultant for Personal Protective Equipment type approval testingPeter Ward IRATA level 3T trainer A Assessor Training Manager Spanset Ltd Line diagrams Chris Blakeley BA HonsRATA level 3T trainer Technical consultant and trainer Lyon Equipment Ltd CEN European Committee for TC160 Technical Committee Protection from falls from a height including working belts WG3 Working Group Personal equipment for work positioning and the prevention of falls from a height PG6 Project Group Rope adjustment devices 104 122 APPENDIX 2 QUESTIONNAIRE SUMMARY OF REPLIES Total number of replies received was 41 Not all respondents answered all of the questions 1221 ROPES Table 9 Question Which three ropes do you most regularly use Main Support Safety Backup Hauling Make Type Diameter mm Number of replies Low stretch 105 22 18 10 Low stretch 110 1 1 1 Low stretch 115 1 2 1 Low stretch 130 1 Beal Dynamic 110 1 9 Lyon Dynamic 105 12 Blue water Dynamic 110 1 1 Dynamic 110 1 1 Low stretch 110 2 1 Low stretch 105 8 8 5 Low stretch 110 1 1 Edelrid Dynamic 110 1 Edelweiss Dynamic 110 1 2 Low stretch 105 7 5 4 Low stretch 110 2 1 1 Doublebraid 160 1 Polypropylene 160 1 Marlow Dynamic 110 1 4 Low stretch 105 1 1 1 Dynamic 110 1 1 Low stretch 160 2 Polyester braided Low stretch 120 1 Low stretch 100 3 3 1 Mammut Dynamic 110 1 Lyon branded rope is made by Beal Vienne France 1222 TYPE A B C DEVICES Table 10 Question Which devices do you use BackUp Device Which backup device do you use Make Device name N of replies Petzl Shunt 27 Komet Stick Run As a work positioning lanyardWild Country Ropeman 11 Chest Ascender Which chest ascender do you use Make Device name N of replies Petzl Croll 36 Anthron AC30 1 Hand Ascender Which hand ascender do you use Make Device name N of replies Basic 4 Petzl Ascension 37 ISC Handled ascender 1 Descender Which descender do you use Make Device name N of replies ID 2 Grigri 2 Figureof8 2 Petzl Autostop 1 1223 Hardware ratings Respondents were asked to rate the performance and ease of training of the devices which they Table 11 Rating of the performance and ease of training of the different devices used Rating Training Device Poor Satisfactory Good Easy Difficult Petzl Shunt 13 14 20 4 Komet Stick Run 1 1 Wild Country Ropeman 8 2 Petzl Croll 1 13 27 22 2 Anthron AC30 1 1 Petzl Ascension Basic 11 27 27 ISC handled 1 Petzl Stop 13 23 22 2 Petzl ID 2 1 Figure8 1 1 1 Autostop 1 1 1224 Connections to harness Table 12 Question What do you use to connect devices to your harness What do you use to connect the backup device to your harness Connector Length range mN of replies Lanyard single 06 or 10 twin 15 Cows tail 05 to 20 25 Strop What do you use to connect the hand ascender to your harness Connector Length range mN of replies Lanyard 06 to 10 12 Cows tail 05 to 13 25 Strop 06 to 20 flat tape3 Table 13 Question What do you use for the operative to clip into anchors Connector Length range mN of replies Lanyard 06 to 10 and 15 14 Cows tail 02 to 10 25 Strop 3 1225 Rope Protectors Table 14 Question Which rope protectors would you use Location Type N of replies Canvas PVC Velcro sleeve 24 Carpet square 19 Wire strop 1 Parapet edge rollers 5 Padding eg kit bag gloves etc 8 Parapet wall close to anchor point Rubber compressor hose pipe 3 Canvas PVC Velcro sleeve 32 Re belay 7 Projection midway Wire strop 2 Arboriculture Cambium saver 1 1226 Knots Table 15 Question Which knots do you regularly use Knot Number of replies Overhand 3 Figure8 28 Figure9 32 Clove hitch 5 Figure8 onthebight 11 Bowline 4 Double fishermans 9 Alpine butterfly 27 double fishermans 1 1227 Knots versus sewn terminations Table 16 Question Do you prefer to use knots or sewn terminations Knots No preference either where applicable connections of replies 27 6 3 Table 17 Question Which prusik knots do you regularly use Knot N replies Bachman knot 8 Kleimheist knot 2 Prusik knot 15 French prusik 1 Blake knot 2 Distel knot 1 123 APPENDIX 3 ROPE ABRASION Table 18 Summary of abrasion resistance of rope over different edges using different protection Type of edge Protection used Peak load kNApprox min load kNTotal test time minutes Approx number of cycles Damage incurred None 180 036 3 15 Rope sheath severed Lyon PVC 155 047 20 100 Rope sheath severed core damage PVC scraps 155 050 60 300 PVC melted removed fabric intact Air line pipe 178 038 15 75 Rope sheath severed core damage Lyon canvas 155 047 54 270 Rope sheath severed Petzl rollers 134 059 120 600 Aluminium stains on rope otherwise OK Carpet foam backed161 040 5 25 Rope sheath severed None 148 050 120 600 Slight sheath damage concrete polished Lyon PVC 149 046 60 300 PVC melted removed rope glazed PVC scraps 160 046 30 150 PVC melted removed creeps off edge Air line pipe 171 049 10 50 Pipe worn through providing no protection Lyon canvas 143 047 60 300 Both canvas and rope slightly glazed Petzl rollers 134 058 100 500 Aluminium stains on rope otherwise OK Concrete coping Carpet foam backed143 049 15 75 Large hole in carpet slight sheath damage None 175 039 2 8 Rope sheath severed Lyon PVC 167 048 20 100 Rope sheath severed PVC scraps 164 048 60 300 PVC melted removed fabric intact Air line pipe 184 037 15 75 Rope sheath severed Lyon canvas 147 045 90 450 Rope undamaged slight wear on canvas Petzl rollers 138 058 60 300 Aluminium stains on rope otherwise OK Concrete Carpet foam backed144 056 12 60 Rope sheath severed core damage 112 124 APPENDIX 4 TEST MACHINES LOCATIONS AND METHODS The test methods are described in the same order in which the results are presented 1241 Ropes Ultimate static strengthTest machine Instron 100 kN vertical straining frame Location Beal Vienne France A static test machine was used to pull rope samples to destruction The difficulty of terminating the rope without weakening it was overcome by the use of a capstan arrangement Figure 60 Photograph Capstan arrangement used to break rope samples The crossheads were moved apart at a constant speed of 1 mmsec over a distance of 15 m The first full length travel of the upper crosshead serves to stretch the rope The upper crosshead is returned to the start position and the ropes tightened around the capstans A second travel of the upper crosshead may then break the rope if not the sequence has to be repeated The forces were recorded on a chart recorder 1242 Knots Static strengthTest machine Hydraulic long pull rig Location Lyon Equipment Ltd Dent Testing the strength of a single knot presents the difficulty of terminating the other end of the rope To overcome this knots were tested in pairs by making a short lanyard with a knot at each end This arrangement permitted comparative strength tests to be carried out To find average strengths identical knots were used at each end of the lanyard and the test repeated These lanyards were tested in all cases on a simple static pulling rig A hydraulic ram was used to pull the lanyard over a length of travel of 1 m A chain dog arrangement was used to change the position of the fixed anchor allowing the full length of the ram to be used when necessary Figure 61 Photograph Long pull test rig Dent Two knots of the same type were tied in the sample rope at least 250 mm apart to create a short lanyard This assembly was then pretensioned to 2 kN for a minimum of 10 seconds and then allowed to relax for a minimum of 30 minutes The sample was then attached to the of the test machine using connectors with a crosssectional diameter of 12 01mm Force was then applied at a rate of 500 mmmin until the sample broke The maximum force held was recorded 1243 Anchor forces Test machine Mecmesin 25 kN portable load cell Location Firbank Viaduct Cumbria These tests were the only ones performed on site rather than in a test laboratory A pair of ropes Beal Antipodes 105 mm lowstretch were rigged freehanging from the viaduct as required by IRATA Guidelines ie no knots were forces generated by an IRATA level 3 technician moving on them were then studied The forces were measured by continuous readings from an inline load cell Two double figureofeight knots were tied about 1 m apart below the anchor of the working suspension rope A 25 kN capacity load cell was then connected between the knots so that the load was directed through it The load cell was positioned as near to the anchors as possible whilst ensuring it was below any obstructions The output from the load cell was then continuously logged on a portable laptop computer at a sampling rate of 10 Hz Loads on the backup rope were not measured 1244 Rope protectors cycling a load over an edge Test machine 1 Instron 25 kN vertical straining frame Location Leeds University Department of Textile Industries Test machine 2 Lloyd Instruments 50 kN vertical straining frame Location Lyon Equipment Ltd Dent Rope protectors were tested by cycling a weighted rope over an edge Tests were carried out on two test machines an Instron machine at Leeds University and a Lloyd Instruments machine at Dent Both operated on the same design principle a vertical frame which allows an upper crosshead to be moved relative to a fixed lower crosshead A pulley was fixed to the lower crosshead the upper crosshead was cycled up and down This action cycled the rope over the edge of the test bench A steel mass of 85 kg was suspended by the rope below the edge to represent the weight of an operative The rope was then cycled through a distance of 50 mm to represent the operative moving around on hisher rope This cycling distance was chosen as it was slightly greater than the distance in which the sheath weave pattern of the rope was repeated Beal Antipodes 105 mm rope lowstretchused for all the tests The rope was terminated with a double overhand knot The knot was pretensioned to 2 kN for a minimum of 10 seconds before use The rope was connected to the upper crosshead and then directed through a pulley connected to the lower crosshead and over the edge of the test bench A rope clamp was then used to attach a rigid steel 85 kg mass Various edges were then clamped to the edge of the test bench Similarly the various rope protectors were positioned between the rope and edge To run a test the crosshead was first raised until the weight was suspended 150 mm above the floor The upper crosshead was then cycled through a vertical distance of 50 mm at a speed of 500 mmmin Damage to both the rope and protector was inspected at intervals relative to the severity of the edge and the maximum and minimum forces as recorded by the machine were noted Figure 62 Photograph Lloyd Instruments LR50K test machine at Lyon Equipment1245 Devices Rope clamps Static testsTest machine Lloyd Instruments 50 kN vertical straining frame Location Lyon Equipment Ltd Dent These tests were performed on Lyon Equipments computer controlled vertical pull test machine This was programmed to pull the sample until the required load was reached whereupon it held the load for the required time period As the test progressed a graph was produced on the computer screen If the device slipped before the required load was reached this can clearly be seen on the graph Method for minimum working strength tests The sample rope was terminated with an overhand knot This was pretensioned to 2 kN for a minimum of 10 seconds and then allowed to relax for at least 30 minutes before use The rope was then connected to the upper crosshead of the test machine The device was located onto the rope at a minimum distance of 300 mm below the anchor point and connected to the lower crosshead of the machine Force was then applied at a speed of 500 mmmin When a force of 1 kN was reached the distance between the device and the anchor was measured and the position of the device on the rope marked The force was then increased as the upper crosshead moved at a rate of 500 mmmin up to the specified load This was maintained 01 kN3 minutes Specified loads Type A 4 kN with 100 mm slippage Type B 4 kN with 100 mm slippage Type C 3 kN with 300 mm slippage At the end of the test the position of the device on the rope was again marked and the distance from the start position ie the distance slipped measured The maximum slippages allowed by prEN 12841 are given above Following the test the device was examined for distortion or damage Method for minimum static strength tests The test was carried out as in the minimum working strength test except that a single overhand knot was tied below the device to prevent slippage The upper crosshead was then moved at a rate of 500 mmmin up to the specified load and again held for 3 minutes Specified loads Type A 12 kN Type C 6 kN The main concern was that the device did not release the rope whether by distortion of the device or by cutting of the rope Following the test the device was examined for distortion or damage The test is not applicable to Type B devices Dynamic testsTest machine Both catchplate and lanyard rigs at Petzls dynamic test facility Location Petzl Crolles France Two test rigs were used The first was a simple arrangement the device which was to be tested was installed on a rope hanging from a load cell A steel mass was attached to the device by a wire lanyard The weight was raised to the required height and then dropped This test arrangement is specified in the relevant standard Unfortunately it is difficult to accurately replicate tests with this method Exact replication of the orientation of the connecters and the lie of the wire lanyard cannot be guaranteed from test to test this tends to produce inconsistent results The pendulum action of the weight on the lanyard is also a factor The method is also time consuming Each test takes 20 minutes The second rig was more sophisticated in that no lanyard was required The device is installed on a rope hanging from a load cell It is then connected to a steel catchplate weighing approximately 10 kg The catchplate sits between two vertical rails down which the test mass falls The latter is lifted to the required height and then dropped hitting the catchplate and transferring the force to the device on the rope This setup allowed tests to be performed quickly allowing more replications to be carried out as well as producing more consistent results Figure 63 Guided weight of Petzl catchplate test rig Figure 64 Guided weight in contact with catch plate and lower buffer Methods catchplate rig The sample rope was terminated with an overhand knot which was pretensioned to 2 kN for a minimum of 10 seconds and allowed to relax for at least 30 minutes before use This knot was then attached to the load cell of the dynamic test rig and the device located on the rope a minimum of 1 m below the anchor This position on the rope was marked with a marker pen The catchplate was then suspended from the device and located carefully in position The 100 kg rigid steel mass was then raised to a height of either 1 m or 2 m above the catchplate ie either fall factor 1 or 2 and released As required by prEN 12841 Type A devices were subjected to a fall factor 2 drop Type B and C devices to a fall factor 1 drop The peak impact force reached was then deduced from the output of the chart recorder The distance from the start position of the device on the rope to the end position ie the slippage distancewas also recorded These results were then compared to assess performance Descent testsTest machine Ceiling mounted capstan digital temperature probe Location Petzl Crolles France All descender devices were subjected to a descent test which examined temperature rise A 100 kg mass was suspended from the device whilst the rope was pulled upwards by a capstan Heating was measured over a distance of 100 metres Speed was a little difficult to control but was reasonably consistent at around 035 msec Two temperature probes were used to monitor the temperature of the device This was recorded by video camera 1246 Cows tails Dynamic testsTest machine Catchplate drop test rig Location Petzl Crolles France The cows tails were made by tying two knots of the same type in a short length of rope This was adjusted so that its total length was about 500 mm The knots were then individually pretensioned to 2 kN for a minimum of 10 seconds and allowed to relax for a minimum of 15 minutes Following this pretensioning the length of the lanyard was 600 mm 5 mmNote the sewn cows tails on test were not pretensioned One end of the cows tail was then attached to the load cell of the dynamic test rig and the catchplate attached to the lower end The 100 kg rigid steel mass was then raised 12 m ie a fall factor 2 above the catchplate and released The peak impact force was then recorded on the chart recorder 1247 Lanyards Static testsTest machine Hydraulic long pull rig Location Lyon Equipment Ltd Dent Due to the length of these lanyards it was not possible to use the verticalpull Lloyd test machine Instead the simple hydraulic ram rig was used and results had to be read from the digital display as the forces changed Forces recorded were the initial force required to deploy the peak force reached during deployment and the final force required to break the lanyard Even this rig with 4 metres between the anchor points was not long enough for some of the lanyards These were deployed as far as was possible but the final breaking strength could not be established In all the tests the lanyards were tested in the form in which they were supplied ie no conditioning or pretensioning actions were carried outDynamic testsTest machine Catchplate drop rig Location Petzl Crolles France These were performed in the same manner as the cows tail tests but with longer drops corresponding to twice the length of the lanyard ie fall factor 2 The short component energy absorbing blocks were tested with a drop of 4 metres representing a fall factor 2 with the greatest extension permitted by EN 567 Prusik knotsStatic testsTest machine Lloyd Instruments 50 kN vertical straining frame Location Lyon Equipment Ltd Dent These were performed in the same manner as the static device tests see above on Lyon Equipments Lloyd Instruments test machine Test parameters were hold 4 kN for 3 minutes maximum allowed slippages 300 mm 120 125 APPENDIX 5 ABRASION TESTS RECORDED RESULTS 1251 Preliminary tests A Concrete edge unprotected Test duration approx 2 hours 600 cycles Peak load 148 kN min load 050 Flattening of rope some sheath damage polishing of concrete edge Flaw in concrete may have caused rope damage B Steel edge unprotected Test duration approx 5 minutes 25 cycles Peak load 180 kN min load 036 kN Sheath severed C Steel edge roll module protection Test duration 2 hours approx 600 cycles Peak load 134 kN min load 059 kN Flattening of rope black aluminium marks sheath undamaged D Steel edge compressor pipe protection Test duration 32mins approx 160 cycles Peak load 178 kN min load 038 kN Pipe holed sheath severed several core strands cut E Steel edge Lyon PVC protector Test duration approx 20mins 100 cycles Peak load 167 kN min load 049 kN PVC bunched then wore through Edge then unprotected sheath damaged F Steel edge Lyon canvas protector Protector laid flat over edge secured top and bottom to prevent bunching Start time 957 Peak load 155 kN min load 047 kN After 20 mins approx 100 cycles little damage Flattening of rope slight wear marks on canvas Restarted 1020 After a further 20 mins total cycles now approx 200 top layer of canvas worn through slight wear on sheath Restarted 1043 Test stopped at 1057 sheath almost severed Rope protector worn through at contact point Total of 54 minutes approx 270 cycles G Steel edge Lyon PVC protector Protector laid flat over edge secured top and bottom to prevent bunching Start time 1110 Peak load 155 kN min load 047 kN After 5 mins approx 25 cycles top layer of PVC removed rope flattened and stained yellow Restarted 111720 After further 5 minutes total of approx 50 cycles PVC appears to be wearing through quickly Little damage to rope other than staining Restarted 112430 sheath damage observed to begin around 1127 Further 5 minutes total 15 mins approx 75 cycles steel can just be seen through protector causing sheath damage After a further 5 minutes the sheath is totally destroyed and core damage has begun Total of 20 minutes approx 100 cycles H Steel edge Rubber compressor pipe protection Start time 1145 Peak load 178 kN min load 038 kN After 5 minutes approx 25 cycles pipe cut down top to inspect inside Hole already worn through pipe beginnings of sheath damage Rope well blackened with rubber Restarted 1154 After further 5 minutes total cycles approx 50 pipe now has large hole However sheath damaged not that advanced yet Restarted 120210 After further 5 minutes sheath totally destroyed beginnings of core damage Large hole in Total of 15 minutes approx 75 cycles I Concrete edge Lyon canvas protector Protector laid flat over edge secured top and bottom to prevent bunching Start time 1218 Peak load 143 kN min load 047 kN After 20 mins approx 100 cycles fabric slightly polished rope flattened Restarted 1242 After further 20 mins total cycles approx 200 no change Further 70 minutes rope flattened and slightly glazed Canvas glazed on both sides but shows no signs of rupture Total of 110 minutes approx 550 cycles J Concrete edge Lyon PVC protector Start time 1428 Peak load 149 kN min load 046 kN From start PVC grips rope and slides and stretches back and forth over the edge After 5 mins approx 25 cycles the protector shows signs of damage The PVC melts and flakes off staining the rope red Restart 1436 After a further 5 mins total 50 cycles the PVC has gone from the wear point on the edge leaving only fibres showing As a result the protector no longer grips the rope but remains steady Restart 1445 After a further 10 mins total cycles now approx 100 there is little change except for the fibres becoming more glazed Restart 1458 After a further 20 mins both PVC and rope surfaces are very glazed resulting in heat buildup and friction which prevents the rope running smoothly Restart 1521 After a further 20 mins situation little different Rope slides in a jerky fashion causing heat buildup Layers of PVC fused together Total of 60 minutes 300 cycles K Concrete edge Compressor pipe Start 1553 Peak load 171 kN min load 049 kN After 5 minutes approx 25 cycles pipe well worn rope well blackened with rubber Restarted 160030 After a further 5 minutes the pipe has worn right through creating a hole around 20m by 4mm The pipe no longer offers any protection Total of 10 minutes 50 cycles L Concrete edge Petzl roll module Start 1612 Peak load 134 kN min load 058 kN After 40 minutes approx 200 cycles rope flattened and stained grey with aluminium Restarted 935 After a further 60 minutes little change Total of 100 minutes approx 500 cycles M Concrete edge PVC rope bag scraps folded twice to give 4 layersStart 1045 Peak load 160 kN min load 046 kN During initial 67 minutes of the test the PVC grabs and slides with the rope Once the coating has rubbed off this ceases however when one stops the test for inspection it is difficult to reposition the protector in exactly the same place After 10 minutes most of the PVC has rubbed off at the wear point staining the rope blue Restarted 1053 As peak loads are greater on the up part of the cycle than the down the material tends to be pulled up over the edge moving the wear point After a further 10 minutes the PVC has been removed over a long strip above and below the wear point On unfolding the material it is apparent that wear is occurring on all the surfaces at the wear point Restarted 1106 Further 10 minutes PVC gradually slides up over edge until the top layer is no longer protecting the edge The other layers then follow suit Test abandoned at this point Total of 30 minutes approx 150 cycles N Steel edge PVC rope bag scraps folded twice to give 4 layersStart time 1125 Peak load 155 kN min load 050 kN As before PVC grips and slides with rope until PVC coating has been rubbed off After 10 minutes approx 50 cycles localised wear across edge Again difficult to reposition material accurately as rope drags it when returning to the start point Restart 1138 Further 10 minutes results in the material remaining stationary with the fibres providing a smooth running surface The 3 layers of material underneath provide a slight increase in radius over the edge so wear does not occur as fast as with the PVC protector Restart 1151 During the next 10 minute stretch the 4 layers of PVC appear to be providing good protection Peak loads are low indicating smooth running over the edge On inspection the top layer of material is still intact with 3 more layers underneath Restart 1205 Further 30 minutes situation similar to test 25 Rope runs jerkily over material creating heat Wear slow although top layer is almost worn through wear on the three layers restricted to PVC removal Heat has lightly fused layers together Total of 60 minutes approx 300 cycles O Concrete edge carpet Start 1050 Peak load 143 kN min load 049 kN After 5 minutes approx 25 cycles rope flattened pile flattened and polished Restart 1103 After further 5 minutes total 50 cycles rope marked small hole in carpet little protection Restart 1111 After a total of 15 minutes 75 cycles large hole in carpet slight sheath damage P Steel edge carpet Start 1123 Peak load 161 kN min load 040 kN After 2 minutes 10 cycles small hole worn in carpet sheath damage just beginning Restart 1128 After further 3 minutes total 25 cycles sheath destroyed carpet offering no protection Q Paving slab Lyon canvas Start 1150 Peak load 147 kN min load 035 kN After 5 minutes rope flattened but undamaged Rope protector polished but intact Restart 1157 After further 10 minutes total approx 75 cycles little change Rope protector becoming very polished and heat beginning to build up in the rope but no significant damage to either Restart 12 09 Further 10 minutes little change further polishing and heat build up Restart 1222 After another 15 minutes total now 40 minutes approx 200 cycles little changed rope now quite hot Restart 1243 After a total of 50 minutes 250 cycles still no change Restart 1408 After another 20 minutes total 70 350 cyclesery slight damage to the rope protector Rope itself still shows no damage Restart 1432 Final 20 minute stretch brings total to approx 450 cycles R Paving slab unprotected Start 1501 Peak load 175 kN min load 039 kN After 8 cycles sheath is destroyed S Paving slab Lyon PVC Start 1510 Peak load 167 kN min load 048 kN During first 5 minutes PVC covering grips rope until it begins to flake off At end of initial 25 cycles PVC coating removed and material is beginning to wear through Rope stained yellow but otherwise OK Restart 1517 After further 5 minutes total 50 cycles rope heating up and showing slight sheath damage Protector is wearing through slowly Restart 1525 After a total of 15 minutes the hole in the protector is growing and sheath damage is advancing Restart 1533 Final 5 minute period leads to a still larger hole in the protector and sheath failure after 100 cycles T Paving slab roll module Start 1547 Peak load 138 kN min load 058 kN After 20 minutes 100 cycles rope is flattened and shows slight aluminium stains Restart 1610 After total 40 minutes 200 cycles flattening and staining more pronounced Restart 1634 After 60 mins 300 cycles no major changes Sheath stained grey but structurally sound U Paving slab carpet Start 1017 Peak load 144 kN min load 056 kN After 5 minutes 25 cycles small hole in carpet very beginnings of sheath damage Restart 1025 After another 5 minutes total of approx 50 cycles large hole worn in protector no longer appears to be offering any protection however sheath damage still only minor Restart 1033 After only 2 minutes more it is obvious sheath damage has progressed rapidly and the test is stopped by which time core damage is beginning V Paving slab Compressor pipe Start 1048 Peak load 184 kN min load 037 kN After 5 minutes approx 25 cycles the first thing that is apparent is the high loads being generated On inspection the compressor pipe has already worn right through with the rope covered in black rubber and sheath damage beginning Restart 1055 After another 5 minute period the situation has worsened although the sheath damage is still relatively minor The blackening of the rope does however make detailed inspection difficult Restart 1103 After a total of 15 minutes approx 75 cycles the sheath has been destroyed and the rope is coated in rubber for 200mm Without removing the pipe for inspection however little damage is seen W Paving slab PVC scraps Start 1117 Peak load 164 kN min load 048 kN From the start the fabric grips the rope and moves with it Unless restrained it will soon creep up or down and remove itself from the edge By restraining the material and preventing it from moving the rope begins to wear a groove in the PVC coating Once the coating has been removed it will slide over This generates a lot of friction and the rope heats up considerably After 10 minutes50 cycles much PVC has been removed yet the fabric continues to creep around and must be repositioned periodically Restart 1132 After approx 100 cycles20 minutes the top layer of PVC remains intact The rope is now stained blue with a coating of PVC where it crosses the edge The fabric no longer grips the rope and it slides more easily Restart 1148 After a further 20 minutes the top layer of fabric remains intact The fibres however appear irregular and the rope runs jerkily over them Restart 1111 After a full 60 minutes approx 300 cycles the situation remains the same heat has steadily built up due to the jerky running of the rope The fabric however remains intact All four layers are fused together and the back layer shows some damage from the rope X Steel edge Carpet canvas backAfter 9 cycles both carpet and sheath have worn through exposing core Y Coping stone Carpet canvas back20 cycles canvas showing through nylon pile melted together 40 cycles As above progressing further 60 cycles Thin melted layer seems to be holding up Probably due to it simply lying over the rounded edge 100 cycles v thin layer of fused material remains 130 cycles rope running directly over edge Z Paving slab Carpet canvas back10 cycles fibres fusing together 20 cycles edge appears to be showing through 30 cycles little change Rope now flattened and stained with melted nylon 70 cycles fused layer now very thin Slight sheath damage beginning Friction has unfortunately pulled the edge back from the edge of the bench lessening the severity of the abrasion 100 cycles Sheath badly damaged 126 APPENDIX 6 KNOTS STRENGTH TESTS Table 19 Beal 105mm Antipodes low stretchknot testsTest 1 Test 2 Test 3 Knot Breaking force kN Breaking force kN Breaking force kN Overhand 1782 1857 1846 Figure8 1842 1886 2058 Figure9 2234 1971 1888 Figure10 2141 2207 2322 Figure8 on the bight 1791 1798 2080 Bowline 1971 1897 1852 Alpine Butterfly 1858 1923 1762 Fishermans 3698 3780 4187 Double Fishermans 1906 2032 1983 Clove Hitch Slipped at 105 1569 Slipped at 10 Note denotes the measured force when tested on a loop of rope It is not the strength of the knot See discussion on this knot in section 339 Note Test 1 2 3 refer to different ways of tying the knots Test 1 Both knots tied the same way live rope on top as it entered the knot Test 2 One knot tied as in Test 1 other knot tied with live rope on the bottom as it entered the knot Test 3 Both knots tied the same way live rope on the bottom as it entered the knot Table 20 Edelrid 105mm rope low stretchnot tests Test 1 Test 2 Test 3 Knot Breaking force kN Breaking force kN Breaking force kN Overhand 1934 1814 1968 Figure8 2022 2007 1990 Figure9 2501 2152 2162 Figure10 2189 2232 2314 Figure8 on the bight 1858 2047 2145 Bowline 1650 1879 1830 Alpine Butterfly 1908 1942 1902 Fishermans 438 425 445 Double Fishermans 2292 2202 2265 Clove Hitch Slipped at 15 Slipped at 11 159 Note denotes the measured force when tested on a loop of rope It is not the strength of the knot See discussion on this knot in section 339 Note Test 1 2 3 refer to different ways of tying the knots Test 1 Both knots tied the same way live rope on top as it entered the knot Test 2 One knot tied as in Test 1 other knot tied with live rope on the bottom as it entered the knot Test 3 Both knots tied the same way live rope on the bottom as it entered the knotTable 21 Marlow 105mm rope low stretch knot tests Test 1 Test 2 Test 3 Knot Breaking force kN Breaking force kN Breaking force kN Overhand 1948 1947 2040 Figure8 2214 2181 2208 Figure9 2451 2508 2264 Figure10 2468 2468 2571 Figure8 on the bight 2014 2079 2245 Bowline 2117 2010 2129 Alpine Butterfly 2022 2081 2089 Fishermans 4541 4570 4685 Double Fishermans 2196 2258 2331 Clove Hitch Slipped at 125 Slipped at 5 Slipped at 45 Note denotes the measured force when tested on a loop of rope It is not the strength of the knot See discussion on this knot in section 339 Note Test 1 2 3 refer to different ways of tying the knots Test 1 Both knots tied the same way live rope on top as it entered the knot Test 2 One knot tied as in Test 1 other knot tied with live rope on the bottom as it entered the knot Test 3 Both knots tied the same way live rope on the bottom as it entered the knotTable 22 Beal 11mm rope dynamic knot tests Test 1 Test 2 Test 3 Knot Breaking force kN Breaking force kN Breaking force kN Overhand 1458 1457 1562 Figure8 1676 1651 1656 Figure9 1692 1747 1614 Figure10 1744 1733 1761 Figure8 on the bight 1548 1475 1556 Bowline 1397 1465 1392 Alpine Butterfly 1484 1497 1501 Fishermans 2990 2823 2908 Double Fishermans 1672 1663 1599 Clove Hitch 1354 1439 1348 Note denotes the measured force when tested on a loop of rope It is not the strength of the knot See discussion on this knot in section 339 Note Test 1 2 3 refer to different ways of tying the knots Test 1 Both knots tied the same way live rope on top as it entered the knot Test 2 One knot tied as in Test 1 other knot tied with live rope on the bottom as it entered the knot Test 3 Both knots tied the same way live rope on the bottom as it entered the knot127 APPENDIX 7 LANYARDS STATIC TESTS Table 23 Lanyard static tests Test 1 Test 2 Initial tear force kN Peak tear force kN Final break force kN Initial tear force kN Peak tear force kN Final break force kN Comments BH Sala 200 1023 Too long to test Not tested Jerky deployment reflected in peak force Charlet Moser 190 310 2664 196 336 2519 Very smooth deployment P P Too long to test Too long to test Petzl Absorbica 406 731 1610 464 848 2049 Jerky deployment Petzl Absorbica 235 632 1849 346 633 1833 Fairly jerky deployment Spanset 250 630 1954 134 128 APPENDIX 8 TYPE A BACKUP DEVICES MINIMUM STATIC STRENGTH TEST Table 24 Type A Backup devices minimum static strength Device Diameter mm Pass Fail Force to fail kN Comments Ushba Stop Lock Edelrid 105 Not tested Komet Stick Run Edelrid 105 Pass Progressive distortion above 11 rope not released At 12kN device severely distorted Rope jammed in device Petzl Microcender Edelrid 105 Pass No distortion visible Petzl Rescucender Edelrid 105 Pass No distortion visible Petzl Shunt Edelrid 105 Fail 55 Body opens up and releases SSE Stop Go Edelrid 105 Pass Side plate distorts at 11 but does not release rope Device unusable after test Rope jammed in device Tractel Stopfor d Edelrid 105 Pass No distortion visible Troll Rocker Edelrid 105 Fail Side plates distort allowing rope to get jammed sheath fails at 108 core then fails at lower loads Device unusable after test Rope jammed in device Wild Country Ropeman Beal 105 Fail Rope sheath fails at 7 Core then cut Toothed cam cuts rope steadily no slippage is seen All rope was low stretch Note PassFail in the above table only applies in relation to the test and criteria employed and may not be relevant to the safety and practicality of the item in question when it is used in any specific application 136 129 APPENDIX 9 TYPE A BACKUP DEVICES DYNAMIC TESTS Table 25 Type A Backup devices dynamic tests Device rope type Rope brand diameter mm kN Slip mComments Edelrid 105 526 Ushba Stop Lock low stretch ropeMarlow 105 580 Rope broke device distorted rope jammed in device 274 170 235 169 Beal 105 258 173 287 240 hit buffer 223 250 hit buffer Edelrid 105 205 250 hit buffer 319 170 274 175 Komet Stick Run Low stretch ropeMarlow 105 268 168 severe sheath damage 290 200 sheath stripped Komet Stick Run dynamic ropeBeal 11 361 200 sheath stripped 575 055 Device No 1 454 084 Device No 1 301 117 Device No 1 278 143 Device No 1 441 087 Device No 2 Beal 105 349 109 Device No 2 447 128 418 111 Edelrid 105 498 100 402 096 351 112 Petzl Microcender low stretchMarlow 105 358 095 Table continued on next pageDevice rope type Rope brand Rope diameter mm kNSlip mComments 600 052 638 050 Petzl Rescucender dynamic ropeBeal 11 597 051 602 067 612 067 Beal 105 628 067 343 160 512 100 605 090 Edelrid 105 538 099 598 077 563 073 Petzl Rescucender low stretch ropeMarlow 105 553 074 640 048 592 065 Petzl Rescucender dynamic ropeBeal 11 525 066 199 169 236 177 Beal 105 249 250 Hit buffer 201 250 Hit buffer 187 250 Edelrid 105 176 250 Ran off end of rope 280 150 296 146 Petzl Shunt low stretch ropeMarlow 105 252 200 256 172 423 180 Sheath stripped 442 177 Sheath stripped Petzl Shunt dynamic ropeBeal 11 231 180 401 145 366 160 Beal 105 369 160 604 160 485 171 Edelrid 105 415 189 655 091 633 111 SSE Stop go low stretch ropeMarlow 105 518 107 Table continued on next pageDevice rope type Rope brand Rope diameter mm kNSlip mComments 423 081 433 075 SSE Stop Go dynamic ropeBeal 11 388 088 290 250 Hit buffer Beal 105 286 250 Hit buffer 290 250 Hit buffer Edelrid 105 286 250 Hit buffer 453 106 434 130 Tractel Stopfor D low stretch ropeMarlow 105 424 140 310 174 313 132 Tractel Stopfor D dynamic ropeBeal 11 307 145 397 087 323 092 Beal 105 320 099 401 081 375 098 Edelrid 105 350 105 417 071 423 067 Tractel Stopfor D low stretch ropeMarlow 105 471 063 427 069 430 069 Tractel Stopfor D dynamic ropeBeal 11 408 070 Table continued on next page Device rope type Rope brand Rope diameter mm kNSlip mComments no record buffer Sheath stripped buffer Sheath stripped Beal 105 518 Core sheath broke 393 Sheath stripped 409 Peak 1 at sheath break 495 Peak 2 when sheath bunched Edelrid 105 483 Sheath stripped 403 Peak 1 at sheath break 425 Peak 2 when sheath bunched 352 Sheath stripped 387 Peak 1 at sheath break Marlow 105 400 Peak 2 when sheath bunched 467 199 403 Hit buffer Wild Country Ropeman low stretch ropeBeal 11 432 220 397 087 Beal 105 323 092 32 099 401 081 Edelerid 105 375 098 35 105 417 071 Marlow 105 423 067 Troll Rocker low stretch rope 471 063 427 069 Beal 11 43 069 Troll Rocker dynamic rope 408 070 1210 APPENDIX 10 TYPE A BACKUP DEVICES MINIMUM WORKING STRENGTH Table 26 Devices Type A backup minimum working strength test Rope Device Brand mm Type Pass Slip mm Comments Beal 105 Edelrid 105 Marlow 105 Low stretch Ushba Stop Lock Beal 110 Dynamic Not tested Beal 105 Fail 300 Slipped at 23 kN Edelrid 105 Fail 300 Slipped at 25 kN Marlow 105 Low stretch Fail 300 Slipped at 27 kN Komet Stick Run Beal 110 Dynamic Fail 300 Slipped at 31 kN Beal 105 Fail 400 Slipped at 34 kN Edelrid 105 Fail 400 Slipped at 22 kN Marlow 105 Low stretch Fail 400 Slipped at 32 kN Petzl Microcender Beal 110 Dynamic Fail 400 Slipped at 35 kN Beal 105 Pass 10 Edelrid 105 Pass 15 Marlow 105 Low stretch Pass 10 Petzl Rescucender Beal 110 Dynamic Pass 20 Beal 105 Fail 300 Slipped at 23 kN Edelrid 105 Fail 300 Slipped at 25 kN Marlow 105 Low stretch Fail 300 Slipped at 25 kN Petzl Shunt Beal 110 Dynamic Fail 300 Slipped at 27 kN Beal 105 Fail 400 Slipped at 19 kN Edelrid 105 Fail 400 Slipped at 28 kN Marlow 105 Fail 400 Slipped at 24 kN Beal 105 Low stretch Fail 400 Slipped at 21 kN SSE Stop go Beal 110 Dynamic Fail 400 Slipped at 34 kN Beal 105 Fail 300 Slipped at 25peak 35 kN Edelrid 105 Fail 300 Slipped at 22peak 26 kN Marlow 105 Low stretch Fail 300 Slipped at 27 kN Tractel Stopfor d Beal 110 Dynamic Fail 300 Slipped at 25 kN Table continued on next page Note PassFail in the above table only applies in relation to the test and criteria employed and may not be relevant to the safety and practicality of the item in question when it is used in any specific Device brand mm Type Pass Slip mm Comments Beal 105 Pass 15 Edelrid 105 Fail 400 Slipped at 34 kN Marlow 105 Low stretch Pass 25 Troll Rocker Beal 110 Dynamic Pass 15 Beal 105 Pass 10 Sheath damaged Edelrid 105 Pass 15 Very difficult to release Marlow 105 Low stretch Pass 70 Took time to bite Wild Country Ropeman Beal 110 Dynamic Pass 17 Sheath damaged Note PassFail in the above table only applies in relation to the test and criteria employed and may not be relevant to the safety and practicality of the item in question when it is used in any specific APPENDIX 11 TYPE B DEVICES ASCENDERS BODY TEST Table 27 Type B Ascenders Body test Make Model Pass Fail Comments Camp Pilot Pass Slight distortion to top hole on rear of device ISC Handled Pass No deformation Petzl Ascension Pass Distortion to top hole on rear of device Anthron AC30 Pass Some distortion to body may be due to problems with grips Repeated test with 12 mm maillons slight deformation to top hole Kong Chest Fail Top hole failed at 85 kN Repeated with maillons failed at 86 kN Petzl Croll Fail Top hole failed at 122 kN Repeated test with maillons top hole failed at 109 kN Note PassFail in the above table only applies in relation to the test and criteria employed and may not be relevant to the safety and practicality of the item in question when it is used in any specific application144 1212 APPENDIX 12 TYPE B DEVICES ASCENDERS DYNAMIC TESTS Table 28 Type B devices ascenders dynamic tests Rope Test Device Brand Diameter mm Type kNPass Fail Comments 511 Pass 546 Pass Beal 105 Low stretch 514 Pass 594 Pass 655 Pass Edelrid 105 Low stretch 642 Pass 689 Pass 626 Pass Anthron AC30 Marlow 105 Low stretch 677 Pass 435 Pass 415 Pass Beal 105 Low stretch 415 Pass 472 Pass 520 Pass Edelrid 105 Low stretch 485 Pass 446 Pass 474 Pass Camp Pilot Marlow 105 Low stretch 455 Pass 566 Pass 535 Pass Beal 105 Low stretch 483 Pass Only one device used for 620 Pass 604 Pass Edelrid 105 Low stretch 655 Pass 652 Pass 636 Pass ISC Marlow 105 Low stretch 629 Pass Note PassFail in the above table only applies in relation to the test and criteria employed and may not be relevant to the safety and practicality of the item in question when it is used in any specific application Table continued on next page Rope Test Device Brand Diameter mm Type kNPass Fail Comments 459 Pass 456 Pass Beal 105 Low stretch 504 Pass 562 Pass 502 Pass Edelrid 105 Low stretch 594 Pass 641 Pass 605 Pass Kong Camclean Marlow 105 Low stretch 554 Pass 484 Pass 500 Pass Beal 105 Low stretch 474 Pass 527 Pass 492 Pass Edelrid 105 Low stretch 629 Pass 569 Pass 559 Pass Petzl Ascension Marlow 105 Low stretch 514 Pass 469 Pass 482 Pass Beal 105 Low stretch 479 Pass 523 Pass 542 Pass Edelrid 105 Low stretch 558 Pass 536 Pass 562 Pass Petzl Croll Marlow 105 Low stretch 590 Pass Note PassFail in the above table only applies in relation to the test and criteria employed and may not be relevant to the safety and practicality of the item in question when it is used in any specific APPENDIX 13 TYPE B DEVICES ASCENDERS MINIMUM WORK Table 29 Devices type B Handled ascenders minimum work strength test Rope Test Device Brand Diameter mm Type Pass Fail Slip mm Comments Beal Pass 15 Slight sheath damage Edelrid Pass 10 Camp Pilot Marlow Low stretch Pass 15 Releases easily Beal Pass 8 Very easy release Edelrid Pass 10 on all ropes ISC Marlow Low stretch Pass 8 Beal Pass 10 Edelrid Pass 10 Petzl Ascension Marlow Low stretch Pass 10 Note PassFail in the above table only applies in relation to the test and criteria employed and may not be relevant to the safety and practicality of the item in question when it is used in any specific application Table 30 Devices type B Chest ascenders minimum work strength test Rope Test Device Type Diameter mm Brand Pass Fail Slip mm Comments Beal Pass 0 Edelrid Pass 5 Anthron AC30 Low stretch Marlow Pass 5 Beal Pass 5 Edelrid Pass 5 KongDalloz Low stretch Marlow Pass 5 Beal Pass 5 Slight sheath damage Edelrid Pass 5 Petzl Croll Low stretch Marlow Pass 5 Note PassFail in the above table only applies in relation to the test and criteria employed and may not be relevant to the safety and practicality of the item in question when it is used in any specific application 148 1214 APPENDIX 14 TYPE C DEVICES DESCENDERS STATIC TESTS Table 31 Devices type C descenders static tests Rope Test Device Diameter mm Type Pass FailSlip mm Comments AML Edelrid 105 stretch Not applicable Slip not measured Anthron Double Stop Edelrid 105 stretch Knot not required self locking sufficient Locked with handle Petzl ID Edelrid 105 stretch Not applicable Locked with knot Petzl Stop Edelrid 105 stretch Locked as per instructions not with knot SRT Noworries Edelrid 105 stretch Locked off as per instructions rope bent sharply over top edge of device Troll Allp Edelrid 105 stretch Fail Not applicable Locked with knot Survives 3 minutes but device distorted and unusable Troll pro Allp Tech Edelrid 105 stretch Locked with knot No damage visible Note PassFail in the above table only applies in relation to the test and criteria employed and may not be relevant to the safety and practicality of the item in question when it is used in any specific application150 1215 APPENDIX 15 TYPE C DEVICES DESCENDERS DYNAMIC TEST Table 32 Devices type C Descenders dynamic test data Device Brand mm Type kN Slip mComments 242 068 236 077 Beal 105 stretch 252 086 242 083 242 083 Edelrid 105 stretch 217 097 358 042 371 043 AML Marlow 105 stretch 435 041 434 035 Rigged incorrectly 689 037 734 038 Beal 105 stretch 753 031 718 034 718 028 Edelrid 105 stretch 747 032 824 024 843 026 Anthron Double Stop Marlow 105 stretch 815 021 639 036 661 031 Beal 105 stretch 629 032 639 036 661 031 Edelrid 105 stretch 629 032 772 028 747 028 Petz l ID Marlow 105 stretch 782 024 Note table continued on next page Rope Device Brand mm Type kNSlip m Comments Sheath stripped and device jammed onto the rope Petzl Stop BealLow stretch Sheath stripped and device jammed onto the rope 235 Short rope 35m hit buffer BealLow stretch 207 175 EdelridLow stretch 223 160 374 040 400 062 SRT Noworries MarlowLow stretch 384 072 140 25m Did not stop 145 25m Did not stop BealLow stretch 141 25m Did not stop 141 25m Did not stop EdelridLow stretch 155 25m Did not stop 204 100 218 096 Troll Allp MarlowLow stretch 226 091 391 042 356 047 BealLow stretch 337 051 333 047 327 047 EdelridLow stretch 343 049 515 028 553 027 Troll pro Allp tech MarlowLow stretch 617 023 1216 APPENDIX 16 TYPE C DEVICES DESCENDERS WORKING STRENGTH Table 33 Device type C Descender working strength test Rope Test Device Type Diameter mm Brand Pass Slip mm Comments Beal Pass 20 Edelrid Fail 300 Slipped at 28 kN AML Low stretch 105 Marlow Pass 15 Beal Pass 15 Edelrid Pass 15 Anthron double stop Low stretch 105 Marlow Pass 15 Beal Pass 10 Edelrid Pass 7 Petzl ID Low stretch 105 Marlow Pass 5 Beal Pass 20 Edelrid Pass 25 Petzl Stop Low stretch 105 Marlow Pass 20 Beal Fail 300 Slipped at 17 kN Edelrid Fail 300 Slipped at 15 kN SRT Noworries Low stretch 105 Marlow Fail 300 Slipped at 18 kN Beal Fail 300 Slipped at 19 kN Edelrid Fail 300 Slipped at 19 kN Troll Allp Low stretch 105 Marlow Fail 300 Slipped at 19 kN Beal Pass 20 Edelrid Pass 25 Troll pro Allp tech Low stretch 105 Marlow Pass 25 Note PassFail in the above table only applies in relation to the test and criteria employed and may not be relevant to the safety and practicality of the item in question when it is used in any specific application154 1217 APPENDIX 17 LANYARD DYNAMIC TESTS Table 34 Lanyard dynamic tests Device Fall factor Peak impact force kNComments na Failed to record Beal BEP 2 BH Sala 2 1 317 First peak 4 10 Second peak 2 893 Third peak 05 205 First peak Charlet Moser 05 330 Second peak Pammenter Petrie 2 Max force of very short duration Petzl Absorbica I 2 MillerDalloz 2 Spanset 2 484 156 1218 APPENDIX 18 PRUSIK KNOTS Table 35 Prusik knot tests Bachman knot Main rope Brand type mm Prusik cord mm Pass fail Sliding force kNComments ease of release Edelrid 105 Fail 061 Steady slip Beal Baobab Low stretch 135 Fail 1619 Steady slip Easy to release Hawser new Pass NA Little slippage Easy release Hawser used 12 Prusik Regate Edelrid 105 Pass NA Beal Baobab Low stretch 135 Pass NA Hawser new Pass NA Hawser used 12 Accessory Pass NA Slight slippage whilst loading Very easy to release Kleimheist knot Edelrid 105 Fail 0304 Slipped steadily at low loads Beal Baobab Low stretch 135 Fail At 4 kN knot inverts twisting rope and reducing function Hawser new Fail 04 At 4 kN knot inverts as above Very difficult to release Hawser used 12 Prusik Regate Fail Knot inverts at 28 kN Very difficult to release Edelrid 105 Pass Jerky slippage 24 Release OK Beal Baobab Low stretch 135 Pass Hawser new Pass Hawser used 12 Accessory Pass No slippage Release OK Note PassFail in the above table only applies in relation to the test and criteria employed and may not be relevant to the safety and practicality of the item in question when it is used in any specific application Table continued on next page Prusik knot Main rope Brand type mm Prusik cord mm Pass fail Sliding force kNComments ease of release Edelrid 105 Fail 045 Releases easily Slipped at relatively low loads Beal Baobab Low stretch 135 Pass 38 slight slippage Stretches Baobab sheath releases easily Hawser new Pass 28 Slipped during increasing force holds static load Release difficult Hawser used 12 Prusik Regate Pass 35 Slipped slightly Difficult to release Edelrid 105 Pass Little slippage OK release Beal Baobab Low stretch 135 Pass Little slippage OK release Hawser new Pass No slippage Easy release Hawser used Accessory Pass No slippage Easy release Note PassFail in the above table only applies in relation to the test and criteria employed and may not be relevant to the safety and practicality of the item in question when it is used in any specific application Table continued on next pageFrench prusik Main rope Brand type mm Prusik cord mm Pass fail Sliding force kNComments ease of release Edelrid 105 Fail 04055 Slides steadily at low loads Releases very easily Beal Baobab Low stretch 135 Pass 334 starts to slip jerkily Releases very easily Hawser new Fail 25 jerky slippage Reaches 35 kN during jerk Very easy to release Hawser used Prusik Regate Pass Slight slippage as it beds in Releases easily Edelrid 105 Fail 13 Slipped steadily at first then jerkily Very easy to release Beal Baobab Low stretch 135 Fail 3 Slipped steadily at 3 kN Very easy to release Hawser new Pass 40 mm slippage Very easy to release Hawser used Accessory Pass 30 mm slippage Very easy to release Blake knot Edelrid 105 Pass Slight jerks at Easy release Beal Baobab Low stretch 135 Pass Little slippage Releases easily Hawser new 12 Pass Little slippage Releases easily Hawser used Prusik Regate Pass Little slippage Releases OK requires a little unwrapping Edelrid 105 Pass Slight jerks between 34 Beal Baobab Low stretch 135 Pass Sheath stretches releases OK Hawser new Pass Some slippage between 34 Release OK Hawser used 12 Accessory Pass Some stretch Release fairly easy Note PassFail in the above table only applies in relation to the test and criteria employed and may not be relevant to the safety and practicality of the item in question when it is used in any specific application 25CRR rope access Investigaiton into items of personal protective equipmentHSE 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bch aeeD8D NqEeE bch YXRU
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