How to join black QD, 1/4" MFL tail and 19/32"-18 UNF, and what stops it leaking.
Updated 05 September 2026.
Connect Ball-lock liquid disconnect (MFL) to Cornelius corny keg post
How to join black QD, 1/4" MFL tail and 19/32"-18 UNF, and what stops it leaking.
Not a direct fit. Joining Ball-lock liquid disconnect (MFL) to Cornelius corny keg post needs a liquid ball-lock disconnect (snaps over the liquid post).
The two ends
- End A
- Ball-lock liquid disconnect (MFL) (black QD, 1/4" MFL tail)
- End B
- Cornelius corny keg post (19/32"-18 UNF)
- A seals on
- O-ring over the post shoulder; flare face at the MFL tail
- B seals on
- poppet inside the post; the post base O-ring seals to the keg lid
- Part needed
- liquid ball-lock disconnect (snaps over the liquid post)
The part to buy
A liquid ball-lock disconnect snaps over the Cornelius liquid post and carries a 1/4 MFL tail for your beer line. Like the gas one it never uses the post thread; the disconnect grips the post shoulder from the outside.
The black liquid disconnect only fits the liquid post, which stops you drawing beer through the gas line. Fit the FFL swivel or push-in flare fitting to its MFL tail, and keep the tail clean because it seals on the flare, not on tape.
Related connections
Questions and answers
Connect Ball-lock liquid disconnect (MFL) to Cornelius corny keg post?
Not a direct fit. Joining Ball-lock liquid disconnect (MFL) to Cornelius corny keg post needs a liquid ball-lock disconnect (snaps over the liquid post).