Nitrogen air line fittings, brute force?

[voipio]

Look closely at the green collar. There might be some sort of a marking on the end of it to identify the tubing size. I've just looked closely at a blue 6mm push fit collar, and it clearly has a small "6" on it. The tubing does look rather tight inside the collar, suggesting the fitting is 6mm.

Just looked at a few images of push in connectors, and they all seem to have some sort of size marking, including the imperial sizes. Collar colour doesn't seem to mean anything, regarding the tubing size. The thread is probably 1/4" NPT, with an o-ring for the seal, not PTFE tape, so look for an o-ring and short thread on any replacement fitting. Alternatively use a 1/4" to 6mm straight adapter, with a short piece of 6mm tubing to the outlet panel.

 

[Neilj]

Parallel rather than taper thread with it having an o-ring seal, so my guess would be 1/4" BSPP

 

[RaceDiagnostics]

I'm going to use one of these which is a compression type fitting rather than push on.

 

[bricol]

Had more issues with those types than push-fit fittings - the tube can get damaged.

But as mentioned by voipio, I can't recall seeing a push-fit fitting that doesn't have the size marked on it - either on the flat face, or on the side of the collar. Colour only means something to individual manufacturers relating to their own ranges - and all metal ones have no colour of course. They seal with an internal o-ring - so if it is now leak free, and the tube isn't coming out, then job done. The o-ring gets damaged if the end of the tube isn't cut cleanly - proper tubing cutters make less of a mess than a simple knife blade and then cause less damage to the fitting seal.

Reliable enough to be used in air brake systems etc.

 

[RaceDiagnostics]

Look closely at the green collar. There might be some sort of a marking on the end of it to identify the tubing size. I've just looked closely at a blue 6mm push fit collar, and it clearly has a small "6" on it. The tubing does look rather tight inside the collar, suggesting the fitting is 6mm.

Just looked at a few images of push in connectors, and they all seem to have some sort of size marking, including the imperial sizes. Collar colour doesn't seem to mean anything, regarding the tubing size. The thread is probably 1/4" NPT, with an o-ring for the seal, not PTFE tape, so look for an o-ring and short thread on any replacement fitting. Alternatively use a 1/4" to 6mm straight adapter, with a short piece of 6mm tubing to the outlet panel.

 

[bricol]

6mm it is then.

They usually are tight enough not to accept over-size tubing - ie you can get 12mm into 1/2" fittings, but it won't stay there under pressure, but can't usually get 1/2" into 12mm.

Send a metric machine to the US . . . try to find suitable replacement tubing . . swap fittings to imperial