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#25257 - 11/01/06 12:58 AM Re: Harness Safety [Re: rg@ofmc]
fear Offline
enthusiast

Registered: 06/27/03
Posts: 221
Loc: New England
I've often wondered how much a HOT biner compromises the strength of the nylon.

I've done some pretty long, screaming raps on a hot day and have burned my skin on the f'in biner or belay device. Most of us have.

I wonder if his loop was severely worn thin and the large amounts of heat coming off a climb like that had something to do with it. Sure, BD's test of a 90% cut belay loop still held 777 pounds. But what if that same biner was 220 degrees?

Sounds like I need some more time on my pull tester....

-Fear

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#25258 - 11/01/06 01:09 AM Re: Harness Safety [Re: fear]
Mike Rawdon Offline

Carpal Tunnel

Registered: 11/29/99
Posts: 4276
Loc: Poughkeepsie
I'm pretty sure nylon does not melt at 220 F. IThe table I found when I googled it lists temps in the 420 - 490 F range.

And the belay loop end of the biner is generally the COOLEST part of the whole assembly. So if you're flying down, you might glaze the rope on the ATC, but you're not going to burn through the BL.

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#25259 - 11/01/06 01:36 AM Re: Harness Safety [Re: Mike Rawdon]
fear Offline
enthusiast

Registered: 06/27/03
Posts: 221
Loc: New England
I wouldn't think it would melt through. But I guess the question is what sort of strength reduction does Nylon 6,6 suffer under high heat? What about old, worn, nylon?

I'm going to try and get one of those super-accurate laser thermometers and take some readings on a hot carabiner after some screaming raps.

I've got no idea how hot they get, but I do know I've got a little scar from a biner burn of several years ago. (second-degree blistered skin from a brief contact).

Aluminum transfers heat very well so I'd imagine the whole biner could become uniformly very hot with enough time.

I always have tried to keep Spectra bits away from my rap rigs. I know Spectra melts at much lower temps.

Scary stuff
-Fear

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#25260 - 11/01/06 03:19 AM Re: Harness Safety [Re: Kent]
timh Offline
member

Registered: 10/18/00
Posts: 194
Loc: Delaware
Probably not since Cliffhanger has any event prompted so many people to double, triple and quadruple check their harnesses. It might also be interesting to know if harness sales have suddenly spiked.
_________________________
Tim

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#25261 - 11/01/06 04:06 AM Re: Harness Safety [Re: timh]
socialist1 Online   content
member

Registered: 08/05/04
Posts: 147
Loc: New Brunswick, NJ

Out of curiousity, what are people's opinion about making a little loop of cord as a backup to the belay loop?

The only problems I see are that it will make things a little bulkier and that it might cause the belay loop and tie-ins to wear a little faster. Im not sure that the faster wear would out-weigh redundancy IMO.

Ross

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#25262 - 11/01/06 04:27 AM Re: Harness Safety [Re: fear]
MarcC Offline
Carpal Tunnel

Registered: 07/10/00
Posts: 3532
Quote:

I'm going to try and get one of those super-accurate laser thermometers and take some readings on a hot carabiner after some screaming raps.

I've got no idea how hot they get, but I do know I've got a little scar from a biner burn of several years ago. (second-degree blistered skin from a brief contact).




Ya know, you could just rap a bit SLOWER!
_________________________
- Marc

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#25263 - 11/01/06 05:04 AM Re: Harness Safety [Re: socialist1]
Steven Cherry Offline

veteran

Registered: 12/23/99
Posts: 1300
Loc: New York, N.Y.
Out of curiousity, what are people's opinion about making a little loop of cord as a backup to the belay loop?

It was one of my suggestions, in the post where I suggested that a biner would be better than nothing if you were already concerned about your belay loop, a suggestion that rg ran all the way into outer space with. (200-300 lbs was intended to be much more than the weight of the climber already, by the way).

Anyway, my first harness didn't have a strap and a buckle, instead there were two loops that came nearly together and you used webbing or supertape with a waterknot. So other than needing to make sure you have some tails to the knot and watch for any significant slippage, it's fine.

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#25264 - 11/01/06 11:06 AM Re: Harness Safety [Re: socialist1]
Mike Rawdon Offline

Carpal Tunnel

Registered: 11/29/99
Posts: 4276
Loc: Poughkeepsie
Quote:


Out of curiousity, what are people's opinion about making a little loop of cord as a backup to the belay loop?





I agree with SC; this is a reasonable soultion. BUT... it should be construed as a temporary fix. If your harnes is so worn that you need to add a second BL, then you'd better replace it ASAP.

Either that or you're uber-paranoid, backing up a visibly-fine loop. I'm sure there are some folks who are doing this already with new-ish harnesses, as a result of Todd's accident. (These climbers can be identified away from the crag by their belt AND suspenders attire)

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#25265 - 11/01/06 02:59 PM Re: Harness Safety [Re: Mike Rawdon]
Timbo Offline
addict

Registered: 12/23/99
Posts: 694
Loc: Delaware
With regard to the heat issue, according to eyewitness accounts, the rap device used was a gri-gri. I've never really rapped a long route with a gri-gri, so I wonder does it dissipate heat better or worse than an ATC. My intuition says better (more metal+larger area of contact with the rope), but that opinion is lacking any scientific data.

TS
_________________________

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#25266 - 11/01/06 05:09 PM Re: Harness Safety [Re: Timbo]
GOclimb Offline
Pooh-Bah

Registered: 03/26/01
Posts: 2359
Loc: Boston
Quote:

With regard to the heat issue, according to eyewitness accounts, the rap device used was a gri-gri. I've never really rapped a long route with a gri-gri, so I wonder does it dissipate heat better or worse than an ATC. My intuition says better (more metal+larger area of contact with the rope), but that opinion is lacking any scientific data.

TS




In my experience rapping on a gri-gri, it gets extraordinarily hot. More so than an ATC, at least on fat ropes.

GO

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