Tech Tip: What's With Kilonewtons?
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Posted 06/14/16
Tech Tip:
Question: “Why is gear rated in kilonewtons? Why not pounds or kilograms? I know a car weighs about 4000 pounds … what’s a newton?”
We get this question a lot, because it’s easy to get confused by the nomenclature.
All modern equipment is rated in kilownewtons (kN),—instead of the more familiar “pounds” or “kilos”—pretty much because the “newton” is THE standard unit of force, according to the International System of Units. Technically, Americans aren’t bound by this, but it’s the common terminology of the rest of the world’s gear builders, so it makes sense for us, too.
In the old days, when gear was marked in pounds or kilograms, it caused heartburn; way too often, we’d hear from folks who towed their two-ton vehicle halfway across some state with a carabiner, figuring they were good to go, because the ‘biner said “4,000lbs” on it. Of course, they were wrong. Very wrong. Don’t tow cars with carabiners. Please.
Here’s why:
The rating of a carabiner indicates the maximum force the product is designed to withstand, not the maximum mass of what you can connect to it.
If you load 4000 pounds onto a 4000-pound carabiner, it’ll hold. Bounce the load and it won’t. Put a couple-hundred-pound load on the same biner, though, and you can bounce all day long on it. This happens every day at crags all over the world: lightweight climbers taking lots of low-force falls, relative to maximum breaking strength.
Anyway, by using a unit of force that’s a bit unfamiliar, it helps removes temptations to do weird and dangerous things with carabiners. That said, should one want to convert kilonewtons into pounds of force, you multiply by 224.8 …
31kN x 224.8 = 6,968.8 lbs-force
That’s it.
So, remember:
#1) Gear is rated in kilownewtons because the world agrees it is so.
#2) Never tow a car with climbing gear.
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