Connect 1/4" NPT to MFL male flare (1/4")
How to join 1/4-18 NPT and 1/4" MFL (7/16"-20 UNF), and what stops it leaking.
Not a direct fit. Joining 1/4" NPT to MFL male flare (1/4") needs a 1/4 NPT to 1/4 MFL flare adapter.
The two ends
- End A
- 1/4" NPT (1/4-18 NPT)
- End B
- MFL male flare (1/4") (1/4" MFL (7/16"-20 UNF))
- A seals on
- on the thread flanks with PTFE tape or paste
- B seals on
- metal 45 degree flare face, never PTFE tape
- Part needed
- 1/4 NPT to 1/4 MFL flare adapter
The part to buy
A 1/4 NPT port, common on regulator bodies and check valves, does not seal against a flare. A 1/4 NPT to 1/4 MFL adapter screws into the NPT port with tape on the NPT end and presents a male flare for your FFL swivels and disconnects.
Tape the NPT end only. NPT is tapered and seals on the thread, so it wants tape; the MFL end is a flare and must stay clean. One part, two opposite sealing rules.
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