USA Pattern Industrial Interchange Air Quick Couplings

These are sockets and plugs of the American air-coupling pattern. The socket carries the shut-off valve and the locking mechanism; the plug is plain and open-ended, so the line closes when the plug is withdrawn. The set photographed covers female-thread, male-thread and hose-tail versions of both halves.

The American pattern most often meant by "USA" is the industrial interchange, whose plug geometry is fixed by the US commercial item description A-A-59439 (formerly MIL-C-4109F), by ANSI/NFPA T3.20.14 and by ISO 6150-B. Suppliers of this profile publish a rated pressure of 300 psi, body sizes of 1/4, 3/8 and 1/2 in, thread forms in NPT, BSPT and BSPP from 1/8 to 3/4 in, and bodies in zinc-plated steel, brass and stainless steel. Note that ISO 6150 Series B is nominally the 1,6 MPa (16 bar) series while makers commonly rate the same profile at 300 psi, about 20,7 bar.

There is a second, unrelated American pattern in wide circulation - ARO 210, also sold under Parker 50, Hansen 210 and Tomco 100/A100. It does not intermate with the industrial interchange. The two are told apart at the plug: the ARO 210 pilot is longer and its ball groove is nearly round. A plug of the wrong American pattern will enter a socket and fail to latch, so the pattern must be established from a sample or an existing socket, not from the size.

When ordering, state the pattern, the body size, the end form, the thread form and size, and the body material. Use a whip-check restraint across hose-to-hose joints, since these profiles vent the trapped line pressure through the plug as it releases.