Bs341 8 vs Ball-lock quick disconnect (ball-lock QD: specs compared
Updated 05 September 2026.
5
specs differ
Bs341 8 and Ball-lock quick disconnect (ball-lock QD differ on 5 specs: designation, size / thread, fitting form, seals on, rating / role.
| Spec | Bs341 8 | Ball-lock quick disconnect (ball-lock QD |
|---|---|---|
| Designation | W21.8 (British designation) | ball-lock QD, MFL or barb tail |
| Size / thread | 21.8 mm x 14 TPI right hand, external (the W21.8 thread) | snaps over the corny post; tail is 1/4" MFL (7/16-20 UNF) or a 1/4"/5/16" barb |
| Fitting form | cylinder valve outlet nut, external | snap-on quick disconnect |
| Seals on | captive O-ring or washer in the nut against the valve outlet | O-ring seals over the post shoulder; the tail seals by flare or clamp |
| Rating / role | the British Standard 341 designation for the CO2 cylinder outlet used across the UK | the universal ball-lock keg connector; gas and liquid are keyed differently |
Questions and answers
How do Bs341 8 and Ball-lock quick disconnect (ball-lock QD compare?
Bs341 8 and Ball-lock quick disconnect (ball-lock QD differ on 5 specs: designation, size / thread, fitting form, seals on, rating / role.