Compression fittings, what am I doing wrong?

[Nebell]

So I've chambered the tube, pushed it in the fitting so it clicks in, screwed it as hard as I could with my fingers (and cut myself in the process) and the tube seemed secure and stays in and won't pull out if I use light force, but it doesn't take much force to pull it out. It was actually rather easy.

I bought these tubes:

EK-HD Tube 10/12mm 500mm (2 pcs) – EK Webshop

Using with these types of fittings:

EK-HDC Fitting 12mm G1/4 - Elox Black – EK Webshop

 

[Nebell]

Here's what the tube end looks like.

 

[Koween]

Compression fittings for hardline are supposed to make an extra seal, that's also tighter. It will also "grab" the tube a little bit more, but it won't make it impossible to pull out. An o-ring pressing against a flat, smooth surface is not designed to hold things in place, but to prevent leaks. There are similar solutions in automotive cooling, but pressures there are higher and there is always some kind of a pin or locking system whose job is to prevent the tube from moving and the job of the o-ring is to seal things.

 

[Nebell]

Compression fittings for hardline are supposed to make an extra seal, that's also tighter. It will also "grab" the tube a little bit more, but it won't make it impossible to pull out. An o-ring pressing against a flat, smooth surface is not designed to hold things in place, but to prevent leaks. There are similar solutions in automotive cooling, but pressures there are higher and there is always some kind of a pin or locking system whose job is to prevent the tube from moving and the job of the o-ring is to seal things.

Thanks!

Think I'll replace all tubing in my half finished design. I think they might be damaged since I've tried to force them few times to see if they fit better.
I got a similar reply from EK, they said that it's normal especially if I wet o-rings before I insert the tube.

 

[Koween]

That's probably a safe bet

 

[Richard R Pope]

Thanks!

Think I'll replace all tubing in my half finished design. I think they might be damaged since I've tried to force them few times to see if they fit better.
I got a similar reply from EK, they said that it's normal especially if I wet o-rings before I insert the tube.

I took a look at the end of your tubing. It is too rough. After I use a chamfering tool. I then take a fine file and dress the end of the tubing so that there are no longer any rough edges. I use a soapy water mixture to lubricate the tubing and the o-rings. You must insure that the tubing slides into both o-rings. The compression nut only needs to be screwed down in a firm manner. Once the soapy water dries, the tube will be firmly held in place. The big difference between our cooling system and an automotive system is the pressure. For all practical purposes we are running at zero pressure unless there is some type of blockage. Automotive systems can run as high as 30 psi.
Thanks,
rich