How to join grey QD, 1/4" MFL tail and 19/32"-18 UNF, and what stops it leaking.
Updated 05 September 2026.
Connect Ball-lock gas disconnect (MFL, check valve) to Cornelius corny keg post
How to join grey QD, 1/4" MFL tail and 19/32"-18 UNF, and what stops it leaking.
Not a direct fit. Joining Ball-lock gas disconnect (MFL, check valve) to Cornelius corny keg post needs a gas ball-lock disconnect (snaps over the gas post).
The two ends
- End A
- Ball-lock gas disconnect (MFL, check valve) (grey 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
- gas ball-lock disconnect (snaps over the gas post)
The part to buy
A gas ball-lock disconnect snaps over the Cornelius gas post rather than threading onto it, so the post thread never touches your line. Its 1/4 MFL tail then joins your flare gas line through an FFL swivel or push-in flare fitting.
The disconnect is keyed to the gas post, so it will not seat on the liquid post. That keying is the safety feature; do not force it onto the wrong post, which sends beer the wrong way. Reach the post through the disconnect, never by threading the post.
Related connections
Questions and answers
Connect Ball-lock gas disconnect (MFL, check valve) to Cornelius corny keg post?
Not a direct fit. Joining Ball-lock gas disconnect (MFL, check valve) to Cornelius corny keg post needs a gas ball-lock disconnect (snaps over the gas post).