These connect directly. W21.8 CO2 cylinder valve mates with BS 341 No.8 CO2 valve without an adapter. Sealing method, the real-world trap, and the exact part to buy.
Updated 05 September 2026.
Connect W21.8 CO2 cylinder valve to BS 341 No.8 CO2 valve
How to join W21.8-14 (DIN 477 / BS 341 No.8) and W21.8 (British designation), and what stops it leaking.
These connect directly. W21.8 CO2 cylinder valve mates with BS 341 No.8 CO2 valve without an adapter.
The two ends
- End A
- W21.8 CO2 cylinder valve (W21.8-14 (DIN 477 / BS 341 No.8))
- End B
- BS 341 No.8 CO2 valve (W21.8 (British designation))
- A seals on
- captive O-ring or washer in the nut against the valve outlet
- B seals on
- captive O-ring or washer in the nut against the valve outlet
- Part needed
- none, direct fit
BS 341 No.8 is the British name for the same W21.8 CO2 outlet, so a W21.8 regulator fits a cylinder labelled BS 341 No.8 directly. UK, European and Oceania CO2 kit converges on this one thread under several names.
The naming is the only difference: W21.8, DIN 477 No.6 and BS 341 No.8 are one connection. Confirm your cylinder is not instead a North American CGA-320, which needs a cross-standard adapter, before assuming a UK regulator will fit.
Related connections
Questions and answers
Connect W21.8 CO2 cylinder valve to BS 341 No.8 CO2 valve?
These connect directly. W21.8 CO2 cylinder valve mates with BS 341 No.8 CO2 valve without an adapter.