Journal

Monday, October 17, 2011

QC Lab: Wet vs. Dry runner strength

qc labLast week I was climbing a classic multi-pitch route in Big Cottonwood Canyon, 30 minutes from the Black Diamond Equipment offices. Clear skies upon arrival but true to the weather lately in the Wasatch there was a downpour mid pitch 2. When we met at the belay, my partner voiced his concern. “Our gear is soaked. Are these runners going to hold if I take a whipper?” “Of course they will,” I assured him. But how much weaker are runners when wet? The truth is I wasn’t sure.

This sparked my curiosity. Is the strength of runners affected when water drenched? People say to use Dynex in snow because Dynex doesn’t absorb water, so are Nylon runners affected more than Dynex runners?

The next day in the lab I got my hands on 10 nylon and 10 Dynex runners. I put five of each in some water to soak for 24 hours. I tested five dry and five wet of each runner in the standard CE tensile testing configuration (something I do almost daily). qc labAll samples broke at the test pin, which is typical. qc lab

 

qc labJust note, runners and quickdraws are rated to 22kN (4946 lbf).

Here are the results:

qc lab

Dynex runners don’t seem to be affected when soaked, which was to be expected. Nylon runners, on the other hand, show about a 10% decrease in strength when wet. Should this slight decrease in strength be concerning? Not really. The strength of these, wet or dry, are well above the product rating and pretty much any force that can be created in the field. Bottom line: runners are crazy strong, wet or dry. So even if my partner had gone for a ride during our rain-drenched climb, he would have been fine.

Note: If your runners or other gear gets soaked, don’t dry it out in direct sunlight. This causes degradation and a potential decrease in strength. How much? Check out an entry from the QC Lab archives: Testing Old Gear from the VRG. Dried out and sun-bleached slings broke at around 11 kN with some as low as 5 kN. That’s 1124 lbf and getting well into sketchy land.


— Sharla Hopkins, QA engineer

Photos

Recent Talk (1)

  • outsidebrian.com
    16 Nov 2011, 6:53PM

    This is really neat page. Makes me feel a lot better about the Black Diamond gear i use...

  • Jason E.
    24 Oct 2011, 5:24PM

    ...or a wet girth hitch?

  • Jerry Sullivan
    24 Oct 2011, 10:51AM

    Thank you for all the great info you provide. This test provides good data for real-life situations.

  • Justin Lukasavige
    24 Oct 2011, 7:18AM

    I had no idea - thanks for sharing, guys.

  • Ben Boykin
    22 Oct 2011, 10:10AM

    Any difference with slings (tied and/or sewn) soaked in sea water?

  • Matt B
    21 Oct 2011, 2:03PM

    Sweet test. I worked for an engineering firm where we tested tensil & shear strength of materials for use in landfill applications - I never thought to take in my climbing gear. What of using a water knot?

  • Conrad Anker
    21 Oct 2011, 9:05AM

    Thanks. To be better informed makes climbing safer. This is why BD is cool.

  • Sean
    20 Oct 2011, 4:40PM

    Would be curious if there's any difference for nylon slings tied with a waterknot.

  • Javier Quiroga
    20 Oct 2011, 11:18AM

    That was a very interesting testing. I am climber and also use to be a mountain guide working mainly in SouthAmerica. I always was curious about strength on climbing equipment.
    By the way I am an Industrial Designer and I am, at all time, looking for new subjects to learn.
    Any way thanks for the info

  • Steve Nutting
    19 Oct 2011, 8:58PM

    Thanks for the good write-up!

    For those asking about the "wet then frozen," I once asked that question about static ropes of the QA guy at Bluewater. He said, "hmm, I don't know. I'll test it for you." So he soaked a chunk of nice new 7/16" static and threw it in the freezer for a few days before testing it to failure. It was several years ago, so I don't remember the exact numbers, but it was a somewhere around a 10% reduction in breaking strength, which meant the rope still held about 6000 lbs.

    I imagine that runners would have similar results and are still more than strong enough. Of course, we'd love to see more tests...keep up the good work!

  • Van
    19 Oct 2011, 7:23PM

    I wonder how the results would vary at subzero temps when wet? I often prefer nylon over dynex just due to durability and cost. I have some dynex I use specifically to cut weight on short flash routes. I am also curious about the results in a dynamic situation with dynamic rope, maybe a screamer.

  • Emma Alderson
    19 Oct 2011, 12:58PM

    You guys do great work in that lab!

  • Al Stebbins
    19 Oct 2011, 12:15PM

    Thanks for the reassurance. I live in New England and it rains all the time. On top of that ice season is coming and everything, as you know, gets wet. Articles like this are extreamly useful, keep up the good work.
    Al Stebbins

  • John
    19 Oct 2011, 11:57AM

    Any insight into what would happen to strength if those soaked runners then became frozen runners?

  • pat
    19 Oct 2011, 11:51AM

    very interesting, when you mentioned snow i wounder what would happen if they were wet and frozen... food for thought, have fun breaking things

  • Brad Acker
    19 Oct 2011, 11:50AM

    Very interesting. Is the CE tensile testing configuration a static or dynamic test? I would think dynamic would be more "real world". I assume Dynex is pretty much the same a Spectra. I have concerns about Dynex/Spectra in dynamic events compared to good old 1" tubular webbing. Any data on that?

  • Tim Burke
    19 Oct 2011, 11:43AM

    Thaks for posting your testing and results. I always appreciate the data when I'm teaching or training and these sorts of questions arise. I always feel confident sending folks to BD's website knwoing they will get great information that is relevant to real life and in language that is digestable. Keep up the good work!!

  • Daniel Weiss
    19 Oct 2011, 10:03AM

    how do i get your job? ... seriously?

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