push-in, push-fit, or instant fittings are a type of easily removedthat allows an air (or water) line to be attached, nominally without the use of tools (a tool is still usually required for cutting tubing to length and removal).
These fittings act similar to the way regular compression fittings work, but use a resilient o ring(normally EPDM) for sealing, and a grip ring (normally stainless steel) to hold the tube in place.
These fittings can be used on all sorts of pipe of many sizes for many purposes. This article only covers domestic-size plumbing in UK and US so far.
The main advantages of this technology over traditional soldered copper or glued plastic are that fittings can easily be unmounted and re-used, speed of assembly, assembly when wet and that the joints are still rotateable after connection.
