UKC

I noticed today that my new winter harness has a belay loop rated to 25kN (well it was before I cut it off!) which is unusual as most are only 12kN. And that got me thinking...

Why are so many harness manufacturers using belay loops rated at only 12kN? Ok, even if they were 25kN then you should always tie in through the harness, but having a higher rated loop couldn't hurt and could offer more options with how you use your harness. Is this a ploy to discourage people from tying into it or just a simple cost saving exercise?

It's not like the manufacturers struggle to make slings rated to 25kN...

In reply to crayefish:

Examples please? I've never heard of a harness with a 12kn belay loop. Always 25kn and I have gone through quite a few harnesses for various reasons.

In reply to mattrm:
Two of my BD harnesses are.

Just found this on the BD website...

"From the Black Diamond Harness Instructions: A Black Diamond harness belay loop can withstand 15 kN (3372 lbf) of force.

CE requirements: The CE required testing is a bit difficult to describe, but basically, the belay loop must withstand 15 kN for a period of 3 minutes.

Actual Black Diamond test data: Though our inline batch test rating is 3372 lbf, we regularly see belay loops test to over 6000 lbf, with a historical average of over 5000 lbf."

So although they rate them to 15kN, they are actually stronger.

In reply to crayefish:

You sure about that? From the BD website:

"From the Black Diamond Harness Instructions: A Black Diamond harness belay loop can withstand 15 kN (3372 lbf) of force.

CE requirements: The CE required testing is a bit difficult to describe, but basically, the belay loop must withstand 15 kN for a period of 3 minutes.

Actual Black Diamond test data: Though our inline batch test rating is 3372 lbf, we regularly see belay loops test to over 6000 lbf, with a historical average of over 5000 lbf."

My WC harness is 22kn. DMM Harnesses are 25kn.

In reply to crayefish:

Heh. Found the same thing.

In reply to mattrm:

Lol yep. Obviously by now it's evident that I should have said 15kn. My bad!

In reply to crayefish:

My coulior harness by BD is 15kn. My petzl corax has nothing on it that I can find or on the website.

In reply to crayefish:




As I understand it, if a harness is subjected to a force of 15kN then the person wearing is likely to have some fairly serious problems that are not about the strength of the belay loop.

In reply to timjones:


That's a fair point. Though fairly serious problems are still preferable to death (even if a non-wear belay loop failure is an almost impossible accident).

In reply to crayefish:

When are you EVER going to put 15kn through a belay loop?

In reply to crayefish:


Death was the serious problem I was referring to

Maybe the only reason slings are rated at 22-25 kN is so that they can still take 9-10 kN after they've been clove hitched, had overhands tied, been abraded a bit, etc.?

None of which should happen to a belay loop. Just a thought.

In reply to Martin1978:

Perhaps not... but you never know. If a belay loop would never see more than 15kN, then why do DMM rate to 25kN? And I think the harness itself (though the tie in points) should withstand 25kN - though haven't got figures to hand.

In reply to climbwhenready:



Yeah that's a pretty good point mate.

Though belay loops are prone to abrasion too... been a couple of deaths as a result.

In reply to crayefish:

Not sure but if I had to guess could it be that all parts of the harness have to be rated for legal reasons (15kn being the lowest allowed) but as they're not designed to be used for anything other than clipping gear to, there's no reason to manufacture them as rated beyond the minimum. Unlike the central belay loop which is.

Not sure I've phrased that very well but hopefully makes sense?

In reply to crayefish:

Why do DMM rate their belay loops to 24kN? Because they can? So that when someone is buying a harness and reading the stats, they have the highest number? Might be cynical, but that's how people look at stats - some people get bothered by it, some don't. Of course then there is also the argument that there is a degree of redundancy in case the harness is owned by an idiot who misuses the equipment. At the end of the day the CE rating is designed by experts in the field and it's what they deem to be the absolute minimum for your safety. Anything over that is a bonus as far as the manufacturers are concerned. What you really have to ask yourself is how you are going to create more than 15kN unless you are doing something worthy of an honourable mention at the darwin awards. If you are belaying, then you have a rope in the system which limits any fall to 13kN. The load will be more or less direct, i.e. it will not load the loop in an odd, weakening, overstressed way. Of course you can clip in direct to a belay using a sling and jump off, but then why would you? As for slings being rated to 24kN, well think about the way a sling gets loaded. It's the top pulley in a fall scenario, i.e. the impact force is much much higher. It could be subject to sharp edges, or prolonged usage leading to weakening through abrasion. There's any number of reasons a sling needs to be that strong...

In reply to mike kann:

Very sound logic. I'll buy that argument certainly.

In reply to add6598:



Doesn't make sense and isn't right, sorry. Not every piece of the harness is rated. Gear loops aren't rated to 15kN, no where near (on most harnesses out there anyway). The elastic holding my leg loops up at the rear aren't rated either.

In reply to crayefish:

The industrial standard seems to be 15kn for the attachment loops.
Most climbing harnesses tend to be higher (more likely a dynamic load you would assume)

i would imagine that 15Kn is the lowest but its still sufficient

In reply to crayefish:



A couple? Who else aside from Todd Skinner?

Wild country vision, 25kN here. Wouldn't have any problems tying into that.

In reply to crayefish:

Some wild optimism going on here, the harness must withstand 15kN and the waist belt part alone 10kN. Abseil/belay loop 15kN. Slings 22kN.
Some items are required to be marked with their strength (slings for example) and for many there is no marking requirement. Since they are CE marked there is no reason to do so.
The ratings are often an advertising/safety confidence thing since anything over the requirements is generally irrelevant, for example there are plenty of bolts out there on the market rated to 25kN because that´s the requirement but they will really get over 70kN before they break. I rate all my lower-off rings at over 50kN because they are, in reality the larger ones pull well over 100kN but who really cares by then?
And ropes aren´t tensile tested so you´ve no idea how strong they are anyway

In reply to crayefish:

On topic but a tangent.

whats the relationship between KG and KN?

I still read Gear ratings as:

25kn = 2500kg

In reply to crayefish:

A harness is static, not dynamic
Therefore it will be good at transferring force from belay loop to you
Do you think you could withstand 15kn? 25kn?

In reply to Choss:

Close. Gravity works at 9.81m/s/s not the more convenient 10 m/s/s

So 25kn would work out at 2548kg

I think!

In reply to mike kann:

Of course, for the purposes of belaying, 15kN is quite enough (I'm thinking of how far and fast I'd get pulled upwards if I caught someone with 15kN of shock force!).

Does it have any implications for Via Ferrata though? Most sets end up just getting connected to the belay loop, but we all know that the fall factors that could be generated in Via Ferrata have the potential to be huge. Is there a maximum impact force or similar for via ferrata lanyards?

In reply to Green Porridge:

Yes, peak force during deployment must be less than 6kN

In reply to Martin1978:


When the Land Rover he is tied to falls off?

In reply to danm:

^ What he said...

In reply to Martin1978:

Right. The answer is never in any belay situation, including factor 2 falls, because the maximum impact load for climbing ropes is typically well under 10 kN and is required by UIAA standards to be under 12 kN, and to even see those loads you'd have to tie the climbing rope to the belay loop rather than using a belay device.

It isn't inconceivable that you might attain loads above 15 kN if you girth-hitch a sling to the belay loop, clip to an anchor, and then take a factor 2 fall on it. If the sling is dyneema, it would probably break, but if not the maximum impact load would probably be over 15 kN. I read some years ago that Petzl tested the maximum impact load of one of their nylon runners in a factor 2 fall and came up with 18 kN, so a nylon runner would probably do the trick too.

Of course, pulling a loop to something above 15 kN is not the same as dropping an 80 kg weight on it in a factor 2 fall. My guess is that since the nylon runner doesn't break (for example, the Sterling Chain Reactor tether withstands three factor-2 falls), there is no way the much burlier belay loop would break, even in these extreme circumstances.

It is well past time to stop citing the Todd Skinner tragedy as any kind of evidence for concerns about belay loop strength. (And the poster who suggested "several deaths" was, of course, unable to come up with any others.) Anything will break if you neglect it for long enough, and there was, sadly, abundant visual evidence that his harness was way, way past the retirement point.

In reply to rgold:


It is inconceivable though. Your presuming a completely static system (or almost, I appreciate that nylon will absorb some of the load). The human body (in the harness) isn't static and will absorb some of the load, breaking in the process. Plus that's why you wouldn't girth hitch a sling to the belay loop and take a factor 2 fall.

In reply to Martin1978:

The only difference here is that you and I understand the term "inconceivable" differently.

Here is an accident that was reported some years ago in the UIAA Journal. A climber clipped to a bolt with a quickdraw through the belay loop, reached up for something, and took a "factor-two" fall on that. "Factor-two" is in quotes because it is really more like a factor-four fall: assuming a quickdraw (including the two carabiners) is altogether four carabiner lengths, this was a fall of eight carabiner lengths with energy absorbed by two carabiner lengths of nylon; that's factor-four. (Ok, not absolutely correct because some small energy-absorbing deformation of the carabiners happens.) Given that the factor-2 load for nylon is in the realm of 18kN, it is a mighty good bet that even with human squishiness that belay loop will get more than 15kN. Or maybe not; in this case a carabiner broke, which still indicates that it was a weaker link than the belay loop.

In reply to rgold:

The climber extended the draw with a 60cm sling and a karabiner, reached to remove a piton above him and slipped. After inspection the karabiner is considered to have broken gate-open (6kN) so it is hard to gain any useful knowledge about what might have otherwise failed. Petzl did the subsequent testing and estimated the possible force at 22kN had the karabiner not failed.
The climber fell 9m to the ground and was uninjured.

In reply to thedatastream:


I'm not sure I follow.


Producing ~20g and ~30g respectively. People do survive that and more but often not in very good shape. Cold war era ejection seats for example accelerate at this sort of rate. So in answer to your question... Potentially but I'd likely be in a bad way though maybe better than if I'd gone further into the floor.

jk

In reply to jkarran:

Speaking of aeronautics: It is said that 12 kN equates to the maximum braking force which can be accepted by the human body (Maximum force adopted for the opening of parachutes!)

I suppose it all depends on how the acceleration is applied to the body.