These connect directly. W21.8 CO2 cylinder valve mates with DIN 477 No.6 CO2 valve (W21.8) 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 DIN 477 No.6 CO2 valve (W21.8)
How to join W21.8-14 (DIN 477 / BS 341 No.8) and W21.8 x 1/14" RH, and what stops it leaking.
These connect directly. W21.8 CO2 cylinder valve mates with DIN 477 No.6 CO2 valve (W21.8) without an adapter.
The two ends
- End A
- W21.8 CO2 cylinder valve (W21.8-14 (DIN 477 / BS 341 No.8))
- End B
- DIN 477 No.6 CO2 valve (W21.8) (W21.8 x 1/14" RH)
- 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
W21.8 and DIN 477 No.6 name the same 21.8mm x 14 TPI right-hand CO2 outlet, so a regulator sold under either label fits a cylinder marked with the other. The difference is only in the naming standard, not the thread.
Do not buy an adapter to go between W21.8 and DIN 477 No.6; there is nothing to adapt, they are one thread. The real split to watch is W21.8 versus the North American CGA-320, which genuinely do not interchange.
Related connections
Questions and answers
Connect W21.8 CO2 cylinder valve to DIN 477 No.6 CO2 valve (W21.8)?
These connect directly. W21.8 CO2 cylinder valve mates with DIN 477 No.6 CO2 valve (W21.8) without an adapter.