These connect directly. EVABarrier 4mm ID x 8mm OD line mates with Duotight 8mm push-in without an adapter. Sealing method, the real-world trap, and the exact part to buy.
Updated 05 September 2026.
Connect EVABarrier 4mm ID x 8mm OD line to Duotight 8mm push-in
How to join 4 mm ID / 8 mm OD and 8 mm (5/16") OD, and what stops it leaking.
These connect directly. EVABarrier 4mm ID x 8mm OD line mates with Duotight 8mm push-in without an adapter.
The two ends
- End A
- EVABarrier 4mm ID x 8mm OD line (4 mm ID / 8 mm OD)
- End B
- Duotight 8mm push-in (8 mm (5/16") OD)
- A seals on
- the 8mm OD is what a Duotight 8mm or John Guest 5/16 collet grips
- B seals on
- double EPDM O-ring on the tube outer wall
- Part needed
- none, direct fit
EVABarrier 4mm ID x 8mm OD line is gripped by the 8mm outer wall, so it push-fits straight into an 8mm Duotight body. The narrow 4mm bore suits gas jumpers where a little pour resistance does no harm.
The fitting grips the 8mm OD, not the 4mm bore, so buy the fitting by the outer size. Cut the tube square, because the double O-ring seals on the tube wall and an angled cut is the usual reason a push-in joint weeps.
Related connections
Questions and answers
Connect EVABarrier 4mm ID x 8mm OD line to Duotight 8mm push-in?
These connect directly. EVABarrier 4mm ID x 8mm OD line mates with Duotight 8mm push-in without an adapter.