/ Belay Plates, Guide Mode Strength?

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petegunn 10 May 2019

Does anyone know why there is no strength rating on belay plates when used in guide mode?

When using my DMM Pivot if bringing up two seconds and if they where both to fall off, all of their combined weight would come onto the pin, surely as with all equipment that is put under load or stress, this pin should have a strength rating!?

Post edited at 10:32
In reply to petegunn:

Is your second getting chubs?

Jim Walton 10 May 2019
In reply to petegunn:

Hi,

I've spoken to DMM about this directly a few months ago.  Their response is detailed below;

"Good morning Jim

Thanks for your support of DMM and our products. Great to hear that you are teaching your clients with our kit.

The shackle ratings when used with 2 ropes = 17kN , 1 rope = 16kN, and 22kN across the shackle."

 

Post edited at 11:05
Phil79 10 May 2019
In reply to petegunn:

DMM pivot (and pretty much any device available from reputable companies) has been tested and certified in accordance with BS EN 15151. 

https://shop.bsigroup.com/ProductDetail/?pid=000000000030218099

I don't know the particular details of that standard, but I cant imagine it wouldn't include the need to test critical load bearing element of a belay device, including the pivot in this case, to a suitable factor of safety above what can realistically be expected.

Further to that, I cant imagine DMM wouldn't consider/test it accordingly either.

Dont worry about it.  

Post edited at 11:07
jimtitt 10 May 2019
In reply to petegunn:

> Does anyone know why there is no strength rating on belay plates when used in guide mode?

> When using my DMM Pivot if bringing up two seconds and if they where both to fall off, all of their combined weight would come onto the pin, surely as with all equipment that is put under load or stress, this pin should have a strength rating!?


There is a strength rating, it's 7kN for all attatchment points for EN 15151

SteveD 10 May 2019
In reply to petegunn:

Further to the points made above, if you are using this in guide mode then there should be very little shock load in the system, so not much more than body weight (x2) on the device.

call it 250kg so about 2.5kn

from memory the load for a lead fall factor 1 on dynamic rope is ~ 8kn so if you somehow manage to get both climbers to lead fall whilst using guide mode, which would be quite a bizarre situation, it would still be below the rated strength of the device although the anchor would take a thrashing!

Rick Graham 10 May 2019
In reply to SteveD:

It will depend slightly on what ropes are used, but I think the in rope slips over the out rope at about 4Kn or so, and you have lost your guide mode.

Jim may be along soon with some better data. 

danm 10 May 2019
In reply to jimtitt:

Actually, it's better than that, for EN15151:2 the static strength requirement is 5kN half/twin, 7kN single rope, and 8kN guide mode. I expect this higher value is to account for the blocking effect in guide mode which makes it less dynamic, in which case it makes sense to have a higher strength for worst case situations. The obvious one being, second belayed on guide mode reaches the belay, so very little rope out, and climbs up level with or above the belay to clip into a runner, but falls off before doing so.

petegunn 10 May 2019
In reply to petegunn:

Thanks for all the replies, I knew it would have had to pass something to make it safe, it just seems odd that on none of my guide plates (Petzl, DMM etc.) none have a stamp on strength rating, like most other equipment.

Is the rating on the paper leaflet that comes with such devices? I can then tell folks to look at this.

Thanks again.

jimtitt 10 May 2019
In reply to petegunn:

So long it has the en number there's no need to mark the strength. It's not on your harness either for example.


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