These safety devices feature a male end—or plug—that is inserted into a female end—or socket—to make a secure, leak-tight seal.
In extremely high-pressure hydraulic applications, a leak or accidental disconnection can cause serious personal injury or damage to machinery. In pneumatic applications, compressed air presents great dangers for hose whip.
They usually feature a one-way sleeve to allow for break-away with a tool when a coupling is clamp mounted. Two-way sleeves allow for one-hand disconnection. In two-way designs, twisting and pulling the two ends breaks the connection.
One of the most common designs is the flat face design such as Aeroquip FD49 (HTMA), FF Series (ISO16028) and FD96 Series Thread to Connect Flush Face, which is available as push-to-connect, threaded or screw-in.
FD49
FF Series
FD96
They eliminate any cavities where fluid or air can rest, thus removing the chance for trapped pressure and leakage. Flat face couplings provide high flow and low pressure drop and their sleeve-locking feature reduces the chance of accidental connection, removing leakage and spillage risks. Some designs allow for connect/disconnect (FD96) under pressure.
Ball or bearing types feature spring-loaded balls lodged in cavities to make the connection such as the HK Series (ISO 7241/1 – “ISO B”) and 5600 Series (ISO 7241/1 “ISO A”). They can be disconnected with just one hand.
HK Series
5600 Series
For aggressive media, one should use non-spill designs. Non-latching couplings are heavily used in medical and test applications where frequent change-outs are common. Bayonet couplings feature two plugs that are engaged and locked by completing a quarter-turn to push the male end into the female socket. Disengaging and separation is the same, but in the opposite direction.
Ensuring a safe end of life with quick couplings is also critical. When a coupling fails, you don’t want it to explode and have locking balls flying out. The design should fail with predetermined leakage paths so fluid comes out slowly.
To avoid unplanned failure, conduct regular inspections and maintenance to check for wear and damage. Ensure there is no brinelling occurring where the locking ball is. Also, a hose could fail before the coupling, so a visual inspection for abrasion and cuts is necessary.
In pneumatic applications, safety couplings—such as Legris Industrial Interchange Safety Couplers from Dixon work quite well. This innovative safety coupler has a unique, two-turn release that quickly vents downstream air pressure before disconnecting, preventing serious injuries associated with hose whip. It is made with a tough composite material which will stand up to the most abusive applications, yet is lightweight.
To find out which couplings will work best for your particular applications, call the hose fitting experts at Milpaws at 314-503-5502.