Also known as pneumatic couplings, quick disconnects, air couplers, quick connect couplers, and quick couplers, hand-operable air-line fittings allow manual disconnection of gas supply lines, including

compressed air Compressed air is air kept under a pressure that is greater than atmospheric pressure. Compressed air is an important medium for transfer of energy in industrial processes, and is used for power tools such as air hammers, drills, wrenches, and o ...

and breathable air (a subset of

breathing gases A breathing gas is a mixture of gaseous chemical elements and compounds used for respiration. Air is the most common and only natural breathing gas, but other mixtures of gases, or pure oxygen, are also used in breathing equipment and enclosed h ...

). Most fittings do not have regional standardization but have become de facto standards through popular adoption.

Mechanical structure

A coupled pair consists of a male nipple or plug and a female coupler or socket. One side is connected to a flexible supply hose; the other may be attached to a manifold, valve, tool, or another hose. A female coupler is used on the supply side, and a male nipple is used on the receiving side. Fitting profiles have identifiable geometry on the male end, but care must be taken to use a compatible coupler. Couplers use springs and balls to lock mating nipples into place. A seal is effected using O-rings along the shaft of the nipple or by compression by the tip. Although incompatible pairs may latch, the sealing performance may be compromised.

Features

* Push-to-connect or automatic couplings automatically lock when assembled. * ISO 4414 "safety" couplings use two-stage unlocking to vent air prior to disconnection, thereby preventing hose whip.

Breathable air applications

For breathable air applications such as SCBA, these may found on both sides of the first-stage and second-stage

pressure regulators A pressure regulator is a valve that controls the pressure of a fluid or gas to a desired value, using negative feedback from the controlled pressure. Regulators are used for gases and liquids, and can be an integral device with a pressure setti ...

(very similar to

SCUBA Scuba may refer to: * Scuba diving ** Scuba set, the equipment used for scuba (Self-Contained Underwater Breathing Apparatus) diving * Scuba, an in-memory database developed by Facebook * Submillimetre Common-User Bolometer Array Two instruments ...

diving regulators) to allow for rapid and tool-free return-to-service. For breathable air applications such as supplied-air and mixed supplied-air with SCBA backup, the quick-disconnect fittings allow movement of a worker from one supplied-air station to another.

Other applications

These fittings or special-service variants may also be found in hydraulic applications and alternative compressed gas applications ( Oxy-acetylene welding and cutting, fuel gases, NSF C-2 food-contact, etc.).

Common fitting profiles by size

European convention uses DN (nominal diameter) to denote a nominal size of each fitting. Various manufacturers specify series or styles for each profile. Fittings are commonly referred to by their manufacturer name/series, i.e., "Rectus 25" for the common European standard. Proprietary designs supported by a single manufacturer are not included in this table.https://www.cejn.com/globalassets/documents/brochures/pneumatic-range/pneumatic_catatalogue_eng.pdf

References