B -- The GateC -- The Basket
D -- The Spine
E -- The Crotch
On the spine of a carabiner there are a series of numbers with a kN next to them. kN stands for kilonewton. A kilonewton is a measure of force, not weight; but for the lay person who is not a physicist, the best way to understand this measurement is to equate it to pounds. In other words, a kilonewton is essentially 224.8 lbs.
Most carabiners show a strength of 18-25 kN (estimated 4046-5620 lbs) along the spine and 6-8 kN (estimated 1348.8-1798.4 lbs) when they are open or crossloaded. The vast majority of climbers are not capable of generating 18-25 kN of force. However, given the right kind of fall, a climber could generate 6-8 kN of force.
Every climber must work to avoid crossloading carabiners. Pay attention to how the carabiner hangs off your harness while belaying or rappelling. Use your belay loop to ensure that the load is on the spine. And watch for situations where the gate to a carbiner might be compromised.
Carabiner gates present the most common problem. In the alpine -- especially in a crevasse rescue situation -- snow may get caught in between the nose and the gate allowing for the carabiner to be open at a nearly imperceptable margin. On rock, a carabiner facing the wall may be pushed open by a protrusion. Each of these problems are solved by careful recognition of the possiblity of a problem. Double check everything and use locking carabiners when possible.
--Jason D. Martin
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