Start with the job and the class. Karam states almost every connector here to EN 362:2004, the European standard for connectors used in fall protection. Class B is a basic connector, the everyday karabiner; Class M is a multi use connector; Class T is a terminal connector, usually fitted at the end of a lanyard so it is loaded in one direction; and Class A is an anchor connector made to clip straight onto a particular kind of anchor such as a beam, tube or rebar. The PN156 and PN154 anchorage hooks are stated to EN 795:2012 Type B, the type for portable, temporary anchor devices, and several aluminium karabiners add EN 12275:2013, the mountaineering connector standard.
Then pick the gate lock. A screw locking gate is locked by hand by turning the sleeve, and the lock indicator versions show when it is properly closed. A quarter turn gate closes and locks itself and opens with a twist of the sleeve, which is quick for frequent clipping. A triple action gate needs three separate movements to open, so it is the hardest to open by accident. Most snap, scaffold, tower and anchorage hooks use a spring gate that closes and locks automatically. Bulb type karabiners have a rounded body and an anti snag key lock nose, shaped to reduce catching on anchors, ropes and webbing.
Finally, match material and size. Aluminium alloy karabiners weigh roughly 75 to 95 g; alloy steel (galvanized) and stainless steel (polished) are heavier, and some steel sizes reach 40 or 45 kN. kN, kilonewtons, is a unit of force, and the minimum breaking strength is the load the maker states the connector holds before it fails. Gate opening decides what a connector can go around: from 12.0 to 27.0 mm on the karabiners and snap hooks used with ropes, lanyards and harness points, and from 50.0 to 140.0 mm on the scaffold, rebar, tower and anchorage hooks that go around tubes, bars and beams. Swivel hooks stop the lanyard twisting, and fall or load indicators show if a hook has already arrested a fall. Prices are on request: call or WhatsApp +91 92440 89060.