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S400 - Air Cylinder dumps all its air on removal

Posted: Sat Aug 14, 2021 10:59 am
by Mainliner
I've got an Air Arms S400 (10m MPR Precision).

Normally, when I unscrew the air cylinder, I just get a momentary 'phut' at about the half-way point.

But now, when I unscrew it, it 'locks solid' at about the half-way point i.e. I'm unable to unscrew it any further, and it dumps all the air. Only then can I remove it fully.

The gun accepts the fully charged (200 bar) cylinder without problems, and there are no leaks.

I've tried unscrewing really fast, to try to get past the mid-point quickly, but that doesn't work (I presume the high pressure on the thread is preventing me from turning the cylinder). I've also 'exercised' the valve at the end of the cylinder by pushing the pin in and out with a plastic dowel. It seems to move freely.

Can I lubricate the valve to try and prevent sticking? And what should I use - WD40 or some sort of silicone lubricant?

Any suggestions greatly appreciated

UPDATE:
Problem now solved - it turns out that there was an air leak at the fill valve on the cylinder. The O-ring on the valve itself was damaged. The cylinder didn't leak when it was fitted to the gun, only when it was removed.

Re: S400 - Air Cylinder dumps all its air on removal

Posted: Tue Aug 17, 2021 10:30 am
by Blackbaronfish
I would use silicon grease on the threads

BBF

Re: S400 - Air Cylinder dumps all its air on removal

Posted: Tue Aug 17, 2021 12:20 pm
by Roger5
Silicon grease might not be a good idea on metal to metal contact, I wouldn't use it myself