First off, carabiners will generally be made from aluminium or steel (which will be carbon or stainless). Which is better? It would be easy to simply say ‘steel is stronger’ but this is not always the case. An NFPA G (general use) rated aluminium carabiner for example will have a long axis minimum breaking strength of or exceeding 40kN, stronger than many steel models. Generally speaking over time steel carabiners will be more durable than aluminium but they are a good deal heavier too, so this could be an important consideration.
Aside from the shape (oval, D, offset D, HMS ‘pear’ etc) & size of a given carabiner, one key feature more than any other will confuse people & that’s the gate mechanism. Carabiners that simply have a gate but no locking mechanism have long been referred to as ‘snap links’ & are totally standard in climbing applications. Locking gate types include the screw gate, two stage auto lock, three stage auto lock, ORCA lock, ‘pinch’ lock, dual direction lock & more. Some three stage auto lockers have a gate sleeve which moves toward the opening, others toward the hinge, in order to open the gate
So how to choose…? Some good questions to ask might include:
- Just how strong do they need to be? If you have an idea of your maximum anticipated system load & multiply this by an appropriate factor of safety (for example, for mountain rescue this might be 10:1), you may well find you don’t actually need a 72kN ‘biner.
- Are they being used for applications where the gates are constantly being opened (say on the ends of lanyards in a rope access setting) or being statically rigged & rarely opened/closed? Two stage auto lockers may be ideal for the former application & more cost effective screwgates for the latter.
- Is the environment they are being used in dirty or have a lot of organic matter, dirt etc (such as in a cave)? If this is the case three stage or ‘triple lock’ carabiners may well jam up & simpler mechanisms could be the go.
- How many carabiners are you going to be carrying, and how far? If the answer is ‘not many & from that truck parked there’ a bunch of high strength steel carabiners won’t be a problem. To contrast, a wilderness Search & Rescue team travelling by helicopter will want to be carrying all aluminium.
SAR has probably a dozen different types of ‘biner in our operational training work cache & more than thirty types in our sales inventory. As we say, when it comes to deciding on the best one ‘it depends on what you are doing’. Hopefully some of the tips above will help you make the right decision.
Written by William Proctor
23 November 2021