These connect directly. Duotight ball-lock gas QD (8mm) mates with EVABarrier 4mm ID x 8mm OD line without an adapter. Sealing method, the real-world trap, and the exact part to buy.
Updated 05 September 2026.
Connect Duotight ball-lock gas QD (8mm) to EVABarrier 4mm ID x 8mm OD line
How to join grey QD, 8mm push-in tail and 4 mm ID / 8 mm OD, and what stops it leaking.
These connect directly. Duotight ball-lock gas QD (8mm) mates with EVABarrier 4mm ID x 8mm OD line without an adapter.
The two ends
- End A
- Duotight ball-lock gas QD (8mm) (grey QD, 8mm push-in tail)
- End B
- EVABarrier 4mm ID x 8mm OD line (4 mm ID / 8 mm OD)
- A seals on
- O-ring over the post shoulder; 8mm push-in O-rings on the tube
- B seals on
- the 8mm OD is what a Duotight 8mm or John Guest 5/16 collet grips
- Part needed
- none, direct fit
A Duotight gas ball-lock disconnect with an integrated 8mm push-in takes EVABarrier 4mm ID x 8mm OD gas line straight in, no flare swivel between them. The 8mm outer wall is what the built-in push-in grips.
The fitting grips the 8mm OD, not the 4mm bore, so buy by the outer size. Cut the tube square, because the push-in O-rings seal on the tube wall and an angled cut is the usual reason a push-in gas joint weeps.
Related connections
Questions and answers
Connect Duotight ball-lock gas QD (8mm) to EVABarrier 4mm ID x 8mm OD line?
These connect directly. Duotight ball-lock gas QD (8mm) mates with EVABarrier 4mm ID x 8mm OD line without an adapter.