What’s the difference between a carabiner and a snap hook?
A carabiner is a metal loop equipped with a spring-loaded gate that will open quickly in order to disconnect the parts of a safety rig. The word comes from the German karabineerhaken for “spring hook for a carbine,” and has been “translated” and shortened to English as carabiner.
A carabiner can only be opened manually by pushing the gate away from the loop.
A snap hook is very similar: it’s a hook with a spring opening, allowing for a cord or rope to enter the hook’s loop, but not leave it unless the spring is opened by using the thumb to pull down on a small knob.
When purchasing a snap hook or carabiner, you should be sure they have a kN rating (kilo-Newton) rating etched on their spine. If the ones you have don’t have these ratings, don’t use them to protect yourself or others from falls!
One kilo-Newton is about 225 pounds. This is a rating for the force of gravity, not how much something weighs. So if you weigh 150 pounds your force of gravity is equal to your mass (150 pounds) multiplied by the speed of your acceleration.
The kN rating is to help you find a snap hook or carabiner that will withstand the force generated by a fall. In other words, as a body falls, the snap hook or carabiner will help keep the body from falling completely to the ground, so long as the kN rating is compatible with the shock force generated by the individual body.
All snap hooks and carabiners are designed to be used by people who weigh no more than 420 pounds.
The American National Standards Institute (ANSI) requires that all types of hardware designed to protect individuals in falls to have at least a 16 kN rating for the gate and a 22.5 kN rating for the tensile load. These ratings translate to 3,600 and 5,000 pounds, respectively. This standard went into effect in 2007, so if your snap hook or carabiner was made prior to 2007, it’s wise to replace it because the new standard provides a 16.3 times increase in the ratings required.
Keep in mind that this rating does not take into account any wear and tear to the gear, so it’s imperative that you check all equipment before using and replace snap hooks and carabiners (and other safety equipment) that has experienced excessive wear. In fact, stopping a fall just once places considerable stress on equipment and it’s smart to replace your tools once they’ve done their (restraining/rescuing) job properly.