John Guest 3/8" push-fit (3/8" (9.5 mm) OD)
Where 3/8" (9.5 mm) OD is used, its real dimensions, and how to connect it to other keg fittings.
Published dimensions
- Designation
- 3/8" (9.5 mm) OD
- Size / thread
- 3/8" (9.53 mm)
- Fitting form
- push-fit collet, imperial
- Seals on
- single O-ring plus stainless collet grab-ring
- Rating / role
- Speedfit acetal fittings rated to 12 bar at 20 C, 6 bar at 65 C
Used on: the UK homebrew beer and gas line size, running from ball-lock disconnects to shanks in one tube standard.
3/8 John Guest and Duotight 9.5mm both take nominally 3/8 (9.53mm) tube and cross over in practice. In the UK 3/8 is the do-everything line size; the shank end is reached with a 3/8 push-fit to 5/8 BSP adapter rather than by threading the tube.
Flare fittings seal on the 45 degree flare face and must never be taped. Push-in fittings seal on an O-ring against the tube wall and need the tube cut square. Barbs seal under a worm clamp. Getting the sealing method right matters more than the thread label, because most homebrew leaks are a taped flare or an unclamped barb.
Connect this fitting
Sources: John Guest Speedfit push-fit fitting technical data · John Guest Speedfit LLDPE / PE tube range and pressure ratings · The Malt Miller John Guest 3/8 to 5/8 BSP shank adapter (PI451215FS)