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Re: [rightarmbad] Pull vrs. Drop Testing:
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vivalargo
Dec 4, 2008, 5:53 PM
Views: 17771
Registered: Nov 26, 2002
Posts: 1512
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rightarmbad wrote: Unless some research shows up that slow pull testing, can mask a significant failure mode under dynamic conditions, then there will be no change to testing.
I think this logic is exactly backwards - and if this logic ever gets challenged in a court of law, I believe it will stand no chance because the assumption (that slow pull testing is all that is required to get a full picture of the consequences) is largely unproven.
The "research" is basically functional, real world climbing, which involves dynamic loading scenarios.
As mentioned earlier, in automotives, they don't allow accident testing to take place in a slow, hydraulic compactor - they require that cars be driven into walls, since that's an actual accident, not a replicatd accident in slow motion (compactor).
Where is the testing supporting the belief that dynamic and static loading result in such similar figures that research is required for the industry to change their ways? Who decided this, when, and on the basis of what comparative (slow pull vrs. drop testing) testing? Like I said, whoever has accepted this prima facia is almost certainly in for a rude awakening if ever challenged in court, which is the main reason companies test gear in th first place (to avoid getting sued).
I'm all but certain that no one actually knows that slow pull testing does not "mask a significant failure mode under dynamic conditions." Sure, this is the case with individual pieces of gear, such and cams and nuts and biners, which put out similar numbers if slow pulled or drop tested. In face, Colin at Black Diamond explained to me how they test SLCDs and
biners and so forth and they dop test the crap out of stuff under far harsher conditions than you could ever encounter in the field (for instance, using static cord with static tie-ins and dropping stuf a country mile - essentially TRYING to break stuff) - but, what about systems (belay systems, rigging systems, and issues like using a redirect off the belay) - these are what remaikn huge question markms for all of us.
Consider the drop tests Rock and Ice mag. did a few years ago on using a Spectra daisy chain as a belay anchor tie off. You could have slow pull tested all the components in the system - the anchor, the rigging (cordelette), the biners, the spectra daisy itself, and all would have returned high performance numbers. But when they actually dropped a 150 lb. weight onto a Spectra daisy connected directly to an anchor, shit started blowing up.
Again, the testing normally done is with individual pieces of gear, whereas systems and procedures - the topic of discussion on these threads - remain huge unknowns and are IMO not going to give up thir secrets with slow pull testing.
Enough said.
JL
(This post was edited by vivalargo on Dec 4, 2008, 6:51 PM)
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Post edited by vivalargo
() on Dec 4, 2008, 6:51 PM
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