Quick couplings are the fittings nobody thinks about until one leaks or will not seat. They matter for a simple reason: every connection between the pump and the nozzle is a potential leak, and each leak costs pressure at the tip.

There are really only three decisions: thread standard, pressure rating, and material. Get those right and the rest is part numbers.

M22, the consumer and light commercial standard

M22 is what comes on most machines below 4,000 PSI. Brass, hand-tightened, sealed by an internal O-ring. Ratings vary by manufacturer, so check the figure for the specific fitting rather than assuming the thread standard sets it.

• AL450-B, 1/4 in F to M22
• AL451-B, 1/4 in M to M22
• AL452-B, 3/8 in M to M22
• AL453-B, 3/8 in F to M22

The 14 mm and 15 mm trap

M22 fittings come with either a 14 mm or a 15 mm nipple. They thread together and they do not seal properly. This is the single most common fitting problem on mixed equipment, and it presents as a slow weep that nobody can trace.

The 15 mm versions are common on European-built equipment and OEM hoses:

• AL451-B-15, 1/4 in M to M22, 15 mm
• AL453-15, 3/8 in F to M22, 15 mm
• AL456-B-15, 3/8 in F to M22, 15 mm reducer
• AL457-B-15, 3/8 in M to M22, 15 mm
• AL458-B-15, M22 M x14 to M22 F x15, which is the adapter between the two standards

Measure the nipple before ordering. It is a millimetre, and it decides whether the joint seals.

Moving between M22 and NPT

Going from a consumer machine to professional accessories means converting M22 to standard quick connects:

• AL557-B, M22 to 3/8 QC plug
• AL455-B, 1/4 in M to M22 reducer
• AL456-B, 3/8 in F to M22 reducer
• AL457-B, M22 to 3/8 M NPT reducer

Standard quick connects

The push-to-connect couplers and plugs used on contractor rigs, in 1/4 and 3/8 in, brass or stainless:

• Brass couplers: AL-QC3/8MB, AL-QC3/8B, AL-QC1/4MB, AL-QC1/4B
• Stainless couplers: AL-QC3/8BSS, AL-QC1/4BSS, AL-QC1/4MBSS
• Plugs: AL-PLUG3/8MB, AL-PLUG3/8B, AL-PLUG3/8MBSS, AL-PLUG1/4B, AL-PLUG1/4BSS

Above 5,000 PSI

Standard couplers are not rated for hydroblasting. The ARF070 series is, at 10,150 PSI: ARF070-1/4F, ARF070-3/8M, ARF070-3/8F, ARF070-1/2M, ARF070-1/2F.

A coupler that fails at ultra high pressure becomes a projectile. Match the rating to the pump with margin, and re-check it every time you change a component.

Quick coupling materials and seals

• Brass for ordinary water and general cleaning. Inexpensive and adequate.
• Stainless for salt, sanitizer, caustic or hot water. Do not mix brass into a stainless system in salt service; the brass corrodes galvanically.
• Buna-N seals for cold water, Viton for heat, oils and chemicals.

Quick coupling maintenance

• Check O-rings daily for flattening or cuts. This is the fix for almost every leaking coupler.
• Use silicone grease or O-ring lubricant on the seal, not on the threads.
• Flush with clean water after detergent or chemical use.
• Clean grit out of the socket before connecting, because grit is what cuts the ring.
• Replace a worn coupler rather than forcing it. A coupler that needs persuasion to seat is already leaking.

Browse the full couplings and fittings range, or send your thread type, nipple size and working pressure and you will get exact part numbers.