In the market for work at height we find several types of connectors available, of many shapes, types of lock, materials. However, few users pay attention to their differences and purposes.
As far as the raw material of the connectors is concerned, the most used in the Brazilian market are steel and aluminum, also called duralumin (an alloy that contains aluminum, zinc, magnesium, among others in its composition).
Galvanized steel connector
This is the most widely used, largely due to its competitive price and greater resistance to cracks that may appear due to falls, knocks, and day-to-day use. However, it is a heavy material, which wears out quickly in humid and sea environments, for example. Oxidation in this type of material is very common.
It is widely used for rescue activities, anchoring, and work where there will be a lot of friction on the part.
Aluminum connector
Its main advantage is the weight in comparison to steel, because with today’s technology, it is possible to have an aluminum connector with the same resistance as steel, but with less weight. Of course, all this applied technology has a price, which makes it a little more expensive than the conventional steel ones.
It is an ideal connector for use in personal safety systems, such as locking seat belts, elevators, lowerators, etc. In this way, it makes it lighter for the user to move around. It is ideal for damp environments, but we must pay attention to the exposure to corrosive chemicals and possible friction with structures, because they damage aluminum more easily.
Types of locks
The most usual ones are thread locking, with manual locking, and therefore special attention should be paid when closing, automatic double locking, with automatic locking right after the user turns and releases the drum from the connector, and there is also the automatic triple lock. This is a less usual model where you need first to apply pressure to thread up the drum in order to open the lock. It is safer because the risk of accidental opening by the user is lower. However, a little more hability is needed and it is common to see users having difficulties to open this part.
Shapes
HMS connectors or carabiners have a large opening and are often used to connect the descender brakes to the belt, as they have more space to accommodate these accessories.
D-shaped carabiners are used in rescue operations or in activities that require more resistance from the part, because they have a good opening and more resistance, due to their shape.
Oval carabiners have a more restricted use for connections with lifelines and accessories, as it has a smaller opening and less working area.
The connectors have information engraved in the body of the piece, such as the rupture load (they are in kN, kilo Newtons, where 1 kN, rounded off, is equal to 100 kgf), that is, a connector that has 25 kN for example, has resistance equivalent to 2.500 kgf.
The rupture load is also highlighted in the longitudinal direction of the part (which is the correct direction of use), transverse direction (where there is loss of more than half of the resistance) and indication of resistance in case the trigger is open. In this case, the resistance will be the lowest of all, putting at risk the integrity of the piece – and the user.