Making a gas tight seal

[john stone]

Small air pistol uses small pressurised Co2 cartridges for a propellent.

When *new* the pressure would maintain itself over many months, but now it only holds pressure for a few weeks. Apparently they can replace the seal, but it needs to go back to the workshop and they charge a lot.

The tip of the cartridge is 7mm in diameter, and is pushed on to a pin that pierces it whilst at the same time the cartridge is pushed against the seal.

I've tried using a couple of layers of the silvery metal-impregnated long life bread bag over the end of the cartridge, but it makes for only a slight improvement.

I know that there are materials out there, since I have a japanese cigarette lighter that i never use and it has held its pressure and it works well after twenty years.

What material could i best use to cut out a small washer to sit on the end of the cartridge that would make a good gas tight seal?

[Tim+]

Rather different pressures though! 3.5 bar for butane and about 50 bar for CO2.

Tim

[F Murtz]

Just buy the proper seal as a spare part, and if the local dealer won't sell it,import it from the makers.

[Bill]

In message , john stone writes

I realise that this seal is not truly safety related, but do you not think that it would be better to have a professional repair done on a weapon such as this. At the very least if there was an accident in the future a home made repair might be used as evidence of not taking proper care of its maintenance.

YES I do know this is a DIY news group!

[F Murtz]

There is nothing magic about air pistols and seal replacement is usually simple.

[Bill]

In message , F Murtz writes

Indeed I realise this, I just wasn't sure that the OP was, not intending to be rude, a "competent person", as in gas regs. By having to ask the question in the first place. I have a BSA Scorpion dismantled in front of me as I type. If he feels that he is then T W Chambers & Co are an excellent supplier of spares.