UKC

Hi.

I'm new to climbing so I need some advise.

I've been looking at DMM quickdraws. I've seen some in V12 in Llanberis for around £9 which are rated to 8kn. I've also seen some more expensive (£15) DMM ones which are rated to 9kn.

Does the extra 1kn make much difference? And will I see the difference in normal use?

In reply to alwyn101: no you wont seea any difference if you did create a fall of 8 kn you would be dead . climbing hardwear is rated much stronger than is needed for extra safty

In reply to winter_burn:
Cheers, I'll be going with the cheaper gear then!

In reply to alwyn101:
Have a bit of a grope of the different draws, preferably with a bit of rope if you can.

I personally use wild wires, they're not the cheapest / most expensive / lightest / newest / most anything really, I just really like the way they handle / feel in your hand

In reply to alwyn101:

You're relating to the gate-open strength, which is a situation a crab shouldn't be loaded under, but can be under certain circumstances. With wiregates the chance this happens is a lot smaller though.

Anyway, 8Kn is realistic force on the top runner, especially when the rope is meandering, or you fall directly onto the belay. See this site for more info:
http://www.bealplanet.com/portail-2006/index.php?page=facteur_chute&lan...

I think 15 Kn or something is the max a human being can handle, not 8 - but am not sure.

In reply to Arjen:
Thanks. There's a lot of good info there.

Very useful for a beginner like me!!

In reply to alwyn101: A quickdraw rated at 8 or 9 kN?? Both karabiners and slings are all rated around 22kN, you're probably looking at the open or cross-gate strength of the karabiner but unless you do something wrong, these are pretty irrelevant because you load them lengthways.

In reply to alwyn101:

This is an important matter that needs clarification.

I am assuming that the OP is referering to the gate open strength of the carabiner. This strength is really the critical strength for a carabiner because it is in the gate open situation that most biner failures happen, especially if the biner is loaded away from the spine.

Contrary to some posts in this thread it is really easy to load the top biner above 7kN - the Beal link above should make this abundantly clear.

There are several factors to look at:

1. The gate open strength of the biner: the legal CE minimum is 7.0kN, however this is really weak by modern standards and the failure of this category of biner in gate open mode is often a critical component is many accidents. There really is no excuse to produce biners this weak any more.

We still see breakages occur in biners with GO strengths of 8.0kN, but the are few and far between. We have even seen biners with a GO of 9.0kN broken, but other design features were at play here - see below. We have not seen a biner with a GO of 10kN break in a climbing situation.

2. Point of load is important - if the gate is open and the load hits the biner away from the spine then even the strongest biners will be likely to deform or fail, but you stand a better chance of walking away if you are using a strong biner that is also well designed....

3. The design of the biner is just as important as the GO strength. A weak 7kN biner with a long 'flatish' top bar and large notched gate is a recipe for an accident because the flat top bar does not guide the rope into the spine and the large notch on the gate tends to catch on wire/bolts and tapes to maximise the leverage.

Good climbing gear is overdesigned, but it is not indestructible and accidents do happen. However, all other factors being equal, you stand a better chance of staying accident free by using strong, well designed kit and understanding how to use it correcttly.

Regards

Simon Marsh

DMM

In reply to Simon Marsh:

That's what I think too. My rope end biners have at least 9 kN gate open strength just because of that reason. The ones that I clip to the bolts or gear are not that critical because the accidental gate opening is lot less likely there.

In reply to alwyn101: I do beleive that in order to pull a force of >7 kN(unless you are foolish enough to climb on a [semi] static line) you would have to fall past your belayer i.e factor 2 fall and this would surely not involve a quickdraw in the system as the fall would be taken on the belay.
What i'm getting at is the fact that the draws are rated such that the forces generated in regular use would not be high enough to break them.
The impact force rating on a dynamic rope, which has to be <12kN? for a single and 8 for double which are tested by dropping a weight (80Kgs for single, 50 for double) from above the anchor to below it (a factor 1.77 fall) thus it is improbable that a quick draw would be part of such a fall therefore it would not be put under that much strain in normal use!
In summary: Biners don't break in normal proper usage - negligence is always to blame!

In reply to anthonyecc:

You are confusing two different scenarios here. Unfortunately I don't how to explain it because of my limited English skills.

But it's possible to generate more than 7 kNs to the QD in a normal climbing situation. This does _not_ mean that this impact force hits the climber too. The high impact force to the QD is caused by the mass of the falling climber _and_ the stationary belayer. Both persons share their own part of the impact force but the QD will hold both.

In reply to anthonyecc:

In summary: Biners don't break in normal proper usage - negligence is always to blame!

Unfortunately not. Take a look at the Beal link - it explains the concept really well. The two key points you are missing are:

1. The force on the top runner is the sum of the force at the belay device and on the climber.
2. The effective length of rope out is reduced by the friction that occurs as the rope runs through biners, across rock etc..

These effects mean that even modest lobs can generate more than 7kN. In the vast majority of situations this will be fine because the gate will be in the closed position. However sometimes the biner's gate will be be open (whiplash/pulling across rock/pulling against the lip of an overhang) and then having a strong, well designed biner could help.

Regards

Simon

In reply to Simon Marsh: how come we dont break more RPs? presuming the beal site is correct then an 8m fall in most scenarios is gonna break a lot of micros/RPs, but i've know people take 50ft lobs onto RP clusters and not snap them... what's the deal?

In reply to abarro81:

The Beal site deals with single ropes and hence sports climbing scenarios. Single ropes have higher impact forces than half ropes.

Thus the Mammut Genesis - a popular 8.5mm half rope - has an impact force of 6.3kN and the lowest impact force used in the model is 7.2kN.

If you also build in the fact that the second rope often takes some load, clusters share the load, nuts deform and start to pull through, slippage happens at the belay plate, knots tighten etc you get down to levels where RPs/Micros can survive.

Regards

Simon

In reply to Simon Marsh: This BMC article http://www.thebmc.co.uk/safety/tech/articles/33_ae_microwire.pdf explains quite well how forces multiply at the top runner.

In reply to Martin W:

A quote from there:
"In fact in tests carried out by the BMC technical Committee, it was found that in typical climbing situations it was not difficult to generate forces between 6kN and 7kN on runners."

In reply to winter_burn:

Why bother posting when you clearly have absolutely no idea what you are talking about? Particularly to a beginner?!? Your comment could actually be dangerous....

<walks away shaking head>