By User:LPNalini @timeAndDate(1274132366)
Carabiners are very common in safety applications for sports and occupations involving ropes and climbing. A carabiner is, essentially, a mechanism for quickly attaching a rope or harness to another rope or harness without having to worry about elaborate knots. In the US, the American National Institute for Standards (ANSI) sets carabiner standards and says that carabiners used in lifetempered aluminum, because aluminum is much lighter than steel and therefore, better for carrying up steep mountains. Some steel carabiners are also available, these being used when even higher strength ratings are required.
For a bit of terminology: the gate of a carabiner is the part that opens and closes and allows you to clip things to the carabiner. The spine of a carabiner is the part opposite to the gate, a solid piece of metal that is also the strongest part of the carabiner.
There are two main aspects to a carabiner: the gate and the shape. We'll talk about shapes here and gates below.
* Standard Oval Carabiners are, well, oval in shape.
** The advantage of the oval shape is that it will pretty readily accept most anything you try to clip to it.
** The disadvantage of the oval shape is that it distributes the load on the carabiner equally over the spine and gate, however the gate is much weaker than the spine.
* D Shape Carabiners
** Will distribute the load more to the spine than to the gate, which is good.
* Offset-D Carabiners
** Essentially a D shape carabiner with a larger gate.
* Pear Shaped Carabiners
** Also essentially a D shape carabiner but wider and able to accept more things clipped to it.
** These are used in applications where multiple ropes all anchor at one spot and are usually manufactured stronger than standard carabiners.
Non-Locking Gate Carabiners
This is the type of carabiner you've probably encountered in miniature form for your key chain or water bottle. The gate is levered by a spring which snaps it shut whenever you let go. There is no locking mechanism so, in theory, the right pressure applied at the wrong time could cause an accident. Nonetheless, these are very commonly used in climbing, so it's safe to suppose that accidents are rare.
Locking Gate Carabiners
A locking gate carabiner will not be as easy to switch from rope to rope, but provides an added level of security by ensuring the gate won't open unless you specifically want it to. Auto-locking mechanisms are available and streamline use as compared to twist locks.
Double Gate Carabiners
Though not widely employed, double gate carabiners will keep the mating mechanisms of two ropes from contacting each other and possibly wearing. That said, the shape of a double gate carabiner makes it mathematically less strong than a standard carabiner.
