How to join grey QD, 1/4" MFL tail and black QD, 1/4" MFL tail, and what stops it leaking.
Updated 05 September 2026.
Connect Ball-lock gas disconnect (MFL, check valve) to Ball-lock liquid disconnect (MFL)
How to join grey QD, 1/4" MFL tail and black QD, 1/4" MFL tail, and what stops it leaking.
Not compatible. Ball-lock gas disconnect (MFL, check valve) and Ball-lock liquid disconnect (MFL) do not share a mating thread, so there is no adapter between them; fit the part that matches your hardware.
The two ends
- End A
- Ball-lock gas disconnect (MFL, check valve) (grey QD, 1/4" MFL tail)
- End B
- Ball-lock liquid disconnect (MFL) (black QD, 1/4" MFL tail)
- A seals on
- O-ring over the post shoulder; flare face at the MFL tail
- B seals on
- O-ring over the post shoulder; flare face at the MFL tail
- Part needed
- matched replacement, no adapter exists
The part to buy
A gas ball-lock disconnect is keyed to the gas post and a liquid ball-lock disconnect to the liquid post, so they are not interchangeable on the keg even though both may carry a 1/4 MFL tail. Fit the gas disconnect to the gas post and the liquid one to the liquid post.
The MFL tail is the same on both, which fools people into thinking the bodies swap. They do not: forcing a liquid disconnect onto a gas post, or the reverse, is what pushes beer up the gas line. Keep gas grey and liquid black and match to the post.
Related connections
Questions and answers
Connect Ball-lock gas disconnect (MFL, check valve) to Ball-lock liquid disconnect (MFL)?
Not compatible. Ball-lock gas disconnect (MFL, check valve) and Ball-lock liquid disconnect (MFL) do not share a mating thread, so there is no adapter between them; fit the part that matches your hardware.