Connect MFL male flare (1/4") to FFL female flare (1/4")
How to join 1/4" MFL (7/16"-20 UNF) and 1/4" FFL (7/16"-20 UNF), and what stops it leaking.
These connect directly. MFL male flare (1/4") mates with FFL female flare (1/4") without an adapter.
The two ends
- End A
- MFL male flare (1/4") (1/4" MFL (7/16"-20 UNF))
- End B
- FFL female flare (1/4") (1/4" FFL (7/16"-20 UNF))
- A seals on
- metal 45 degree flare face, never PTFE tape
- B seals on
- mates against a male 45 degree flare face
- Part needed
- none, direct fit
A 1/4 MFL male flare screws directly into a 1/4 FFL female flare. Both are 7/16-20 UNF and the seal forms where the two 45 degree flare faces meet as you tighten. This is the join that lets you build up a gas line from regulator to disconnect with no adapter.
Do not put PTFE tape on the thread. The seal is the flare face, and tape only holds the faces apart. If a flare-to-flare joint weeps, back off and reseat it square, do not add tape.
Related connections
Sources: MoreFlavor thread types explained (MFL/FFL, NPT, BSP) · KegLand Duotight 9.5mm x FFL (7/16-20 UNF, 1/4 SAE) product data · SAE J512 45 degree SAE flare (7/16-20 UNF) fitting reference