I thank Dan L for his reply. I also thank squarerigger for his post.
I would like to keep this thread informative and positive - as that is the spirit in which i choose to post on this forum.
As always, I respect the advice and opinions of Dan Lehman.
I am a little concerned that the subject matter of this thread may be deviating from the core business of knots and knot theory (and hence may not be of interest to many readers).
Be that as it may, I see that ropes and cordage in general is the base material from which a knot can be formed. So in a way, this discussion on ropes is linked to knots…
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Without doubt, anyone who proposes a theory or a new concept (or any radical new approach to an old problem) is immediately placing him/herself in the firing line of the public (rather like politicians who must face public opinion on a daily basis).
My approach to reducing the published fall rating of a dynamic climbing rope is not supported by certified test data.
It is merely my opinion - so readers and would-be user groups would apply such concepts at their own risk. Merely because I choose to post this theory on the IGKT website is in no way to be implied as approved or endorsed by the IGKT.
Squarerigger made clear remarks about the EN 892 standards.
I sympathise with him and others who may be seeking to gain possession of this document.
Unfortunately, En 892 (and all other such standards) are copyright and are certainly not available for free in the public domain. One has to purchase such standards from the relevant standards body in their nation.
I cannot email or post extracts from EN 892 without attracting negative attention. However, I can identify key test requirements for fair and reasonable analysis by interested parties.
Thus far, all the posts in this thread have accurately reported the key test requirements.
There are indeed three (3) sub-categories of dynamic rope as follows:
- Single - where the rope is tested with an 80kg drop mass and must survive at least 5 EN 892 test falls (impact force must not exceed 12kN on first test fall)
- Half - where the rope is tested with a 55kg drop mass and must survive at least 5 EN 892 test falls (impact force must not exceed 8kN on first test fall)
- Twin - where two rope strands are drop tested simultaneously (ie in parallel as the inseparable twins) with an 80kg drop mass and must survive at least 12 EN 892 test falls (impact force must not exceed 12kN on first test fall)
EN 892 specifies a 5.0m free fall using a 2.8m rope specimen (hence the fall-factor of 1.78… 5/2.8 = 1.78).
Go here for a pictorial overview of UIAA standard 101: http://www.uiaa.ch/?c=310
This site provides a very good synopsis (but is incomplete) of the full EN 892 standard.
To purchase the full EN 892 or EN 1891 standard, you need to place an order through your national standards body. Go here for the international gateway page: http://www.cen.eu/catweb/cwen.htm
If you reside in England, go to: http://www.bsonline.bsi-global.com/server/index.jsp
If you reside in the USA, go to: www.nfpa.org (Note: The US is not a member of the European Union and CE marking is not mandatory)
The full titles of the standards are as follows:
EN 892:2004 Mountaineering equipment. Dynamic mountaineering ropes. Safety requirements and test methods
EN 1891:1998 Personal protective equipment for the prevention of falls from a height. Low stretch kernmantel ropes
For the USA:
NFPA 1983: Standard on Life Safety Rope and Equipment for Emergency Services, 2006 Edition
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Now for the contentious area that I and Dan L are discussing…
When a person buys a dynamic rope, it will have a finite number of falls that it can sustain (given in the hang tag documentation that should be supplied with the rope).
Lets say that you purchase a rope that has a ten (10) fall rating.
At the present time, no rope manufacturer provides any information about how heavy climbers should treat such published fall ratings. (Note: I would respectfully ask that Dan L or anyone else provide me with information to the contrary).
What does this mean?
What should heavy climbers do?
There are no clear answers - only masses of confusing and conflicting information.
I am one of the many climbers who find themselves in a catch 22 situation where I want to climb, but I do so outside of EN 892 test parameters.
The PMI report discussed in previous posts does not clear up the situation.
I have used my own ‘rule of thumb’ approach to this age old problem, and I discussed the principle in a previous post. Here it is again:
I advocate that any fall generating factor one (1) or higher should be counted as one (1) fall towards the ultimate retirement of a climbing rope.
I advocate that heavy climbers reduce the published fall rating of their rope by a proportionality factor determined by dividing 80kg by their respective body mass. For example: A 100kg climber would divide 80/100 which yields 0.8. The published fall rating is then multiplied by 0.8 to give an ‘adjusted’ fall rating (used in conjunction with counting any fall of factor 1 or higher towards rope retirement). All fractions are rounded down conservatively - eg if a figure of 0.86 is calculated, this is automatically rounded DOWN to 0.8.
Note: Climbers who are lighter than 80kg gain no such benefit and should not attempt to increase the published fall rating of their rope merely on the basis of their lesser body mass.
I would also point out that each EN 892 test fall is very severe. They take a 2.8m length of rope and subject it to a 5.0m free fall using a mass specific to one of the 3 categories (single, half or twin). It is a rare event indeed for any climber to take a fall of magnitude 1.78. In my mind, it implies human error - I personally have never sustained a fall greater than factor one in 24 years of climbing. That is not to say that it doesn’t happen - I am only suggesting that it hints of human error (or in some special cases, gross incompetence). The biggest risk factor in sustaining high impact force falls generally occurs when leaving a belay stance on a multi-pitch route. Although the risk is present, it can easily be mitigated by placing protection early and frequently when leaving a belay.
In the context that severe falls exceeding factor one are generally rare, my rule of thumb procedure for reducing published fall ratings is sound.
The most common reason for retiring ropes is general wear and tear on the outer sheath (where the inner core has become exposed). Age is another factor - but heavy usage patterns usually cause sheath damage before the age limit is reached (Note: rope manufacturers do not universally agree on the lifespan of a rope - and this is another gray area). One group of climbers is ‘sport climbers’; this group is more likely than not to approach the fall rating published by the rope manufacturer.
My remark about defending myself against would-be litigants was a pun and I meant no harm - I am happy to withdraw the said remark. Here is another pun: I can only assume that a few US citizens are reading this post and are right now planning future lawsuits against me… I wish them all the best - but they should be advised that my ex wife owns everything I ever had (including my dog).
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So there you have it, a rule of thumb for building in at least some margin of risk reduction in the face of the present status quo - where the prevailing situation is to ignore the problem and let nature take its own course.
Well, I have embraced the problem and done something about it - and my own empirical field testing has thus far proven me right (but I have no documented evidence to show anyone).
Disclaimer: Any person placing reliance on agent smiths ‘rule of thumb’ reductions to fall ratings do so at their own peril. No liability will be accepted for any injury, death or loss incurred as a result of relying on the said information.
By the way, there is a wealth of information published by the many rope manufacturers who are very conservative. Another gray area is with respect to rope lifespan (as stated above).
Oh no, here I go again, producing theories where there was only mass confusion… the big question: How long does a EN 892 / EN 1891 rope last? Try answering that question from the point of view of a new rope stored in a cool dry place and never used…
It is to the rope manufacturers advantage to create a situation where confusion and doubt prevails. This obviously leads to healthy annual rope sales figures where climbers retire their ropes early (yes, this can be seen as good). However, I see no reason to retire a rope for no sound reason. I am a believer in criteria and not hysteria.
Rope manufacturers enjoy the present status quo - as it works in their favour. Its kind of like making a product that never wears out… is this commercially viable?
I leave you to ponder your own thoughts…
agent smith
Edits:
- Added info on EN standards
- Added further elaboration regarding falls and severity of falls
