UKH

Hi,

I've been looking at getting some new ropes. I've noticed that the static ropes seem to have a lower impact force rating that corresponding dynamic ropes. I thought that this should have been the other way around i.e. the static rope impact force should have been a lot higher due to less elasticity and hence higher transfer of force to the climber.

I've tried searching for an answer and thought it might be due to different testing criteria, but have been unable to find any information even on manufacturer websites.

A couple of examples are:

https://www.beal-planet.com/en/low-stretch-ropes/1631-8500-antipodes-105mm....

vs

https://www.beal-planet.com/en/dynamic-ropes/1436-8027-top-gun-ii-105mm.htm...

If anyone could shed some light on this I'd be grateful so that I can understand the safety aspects better.

Thanks in advance.

I'm not particularly au fait with static rope testing regimes, but I would imagine that the tests are different, just like the single vs double rope tests which use a different weight body to complete the test. On Beals site their stat on the static rope is "Low Impact force" which probably means it's a much lower weight or shorter drop distance used. But this is a guess - couldn't find a link to a site to confirm this.

"Since users of low-elongation and static ropes should try to prevent slack in their system and have very small fall factors, the impact for EN1891 is collected from a fall factor of 0.3 and needs to be below 6kN."

https://sterlingrope.com/journal/137-sterling-r-d-report-an-overview-on-dro...

It looks like static ropes are subject to a very different test, fall factor 0.3 Vs 1.7 for dynamic rope.

Static ropes are tested with a lower fall factor of 1.

Thanks to both for a prompt reply - much appreciated.

Which given the numbers at the start of the thread means that you are better off FF1 on the semi static than FF2 on the dynamic. Whilst not a good idea, in an emergency maybe leading on a static where the FF would be small is just about okay. 

As has already been said low stretch/static/semi-static ropes are (usually) tested to EN1891, dynamic ropes to EN892.

I was going to say it's a shame the EN standards ropes (and everything else) are tested to aren't in the public domain, precisely because it's useful for people to be able to see the mandated tests for things in order to understand what figures the manufacturers quote actually mean.
(You can get a look at them for free via a public library, but they're eye-wateringly expensive documents to buy.)

But then I found this straight away with a quick googling - not quite the whole thing, but all the important details are there (including the details of the two different drop tests)..

Dynamic ropes:
https://www.edelrid.de/en/knowledge-base/norms/pics/EN_892_en.pdf

Low stretch:
https://www.edelrid.de/en/knowledge-base/norms/pics/EN_1891_en.pdf