How is the strength of a clipping device such as Caribeener, hook, or chain link calculated? I think it is measured in kilo-newtons. What elements are taken into consideration when that strength is measured?
One of the most critical measures of a clip-ping device is the maximum tension that it can tolerate without failing. I would expect a tester to measure that failure tension by putting the clipping device in a simulated working environment and exposing it to greater and greater tension until it fails. For example, a chain link would be put between two sturdy hooks and then the hooks would be pulled apart until the chain link broke or deformed permanently. Since tension is a force, it’s natural to measure it in newtons or kilo-newtons (1000 newtons). (There are 4.4482 newtons in 1 pound of force.) But what constitutes failure is complicated since anything that is exposed to tension deforms somewhat. However, if the tension is less than a certain threshold, the deformation will be purely elastic—meaning that the device will return to its original shape once the tension is released. But if the tension exceeds that threshold, the deformation will be plastic—meaning that it will be permanent and the device will not return to its original shape once the tension is released. I would expect the rated strength of a clipping device to be a reasonable fraction (probably about 50%) of the tension required to cause plastic de-formation of that device.