Charging pcp air pistols.

[deadeyedick]

When charging a FWB air pistol cylinder the pressure between the cylinder valve and the tank valve can be released before unscrewing the cylinder from the tank. ( if you have a release valve )

On the Walther I find that the release of this intermediate pressure cannot happen without the cylinder discharging as well. Unscrewing the cylinder under pressure is obviously not good for the threads.

Does anyone know of a workaround to this problem that will allow the threads to not take such a beating and to save re engineering something that already may be available.

[David M]

Just use a little lube on the threads, no good going in dry.

[deadeyedick]

Done that......nothing worse than going in dry.

[SamEEE]

On the subject of lubricant and galling:

http://www.targettalk.org/viewtopic.php ... 4&p=224375

http://www.targettalk.org/viewtopic.php?f=4&t=39217

viewtopic.php?t=42225

[Gwhite]

I'm not familiar with the Walther, but the worst thing for thread damage is aluminum on aluminum. Silicone grease is NOT recommended. The team I coach has managed to ruin a couple of Hammerli AP40 cylinders by using them with little or no lube.

We use this anti-seize compound: http://www.all-spec.com/products/41205. ... 7Aodm0gAiw Almost any grease is better than none, but why risk damage with stuff that isn't meant for this application?

You can minimize the problem if you have a relief valve by learning how far you have to unscrew the cylinder to get the valve to close. On the Steyrs, it's only about 1 turn. Then you can vent the pressure & unscrew the rest of the way. The most damage will occur when there are only a few threads engaged, and using this approach should allow venting the pressure before you unscrew to that point.

[Brian Girling]

See:-

http://www.bestfittings.co.uk/shopexd.asp?id=339

This allows you to vent the system (after closing the cylinder valve), note the small hole in the end face which prevents the cylinder being depressed.

[David Levene]

See:-

http://www.bestfittings.co.uk/shopexd.asp?id=339

This allows you to vent the system (after closing the cylinder valve), note the small hole in the end face which prevents the cylinder being depressed.

Great for Steyr users Brian, bot not much help for the OP with his FWB (unless they use the same adaptor).

[deadeyedick]

You can minimize the problem if you have a relief valve by learning how far you have to unscrew the cylinder to get the valve to close. On the Steyrs, it's only about 1 turn. Then you can vent the pressure & unscrew the rest of the way. The most damage will occur when there are only a few threads engaged, and using this approach should allow venting the pressure before you unscrew to that point.

Thanks for the replies. There is obviously no other solution at this time other than to unscrew to the point the cylinder valve is closed and then vent the rest.

I tested and on the LP 400 2 1/4 turns are needed for the cylinder valve to close safely and then after venting the cylinder can be unscrewed with no force on the remaining threads.

I decided to follow the majority opinion regarding not using silicone grease until I buy the Loctite product suggested by Gwhite. Until then I have applied a small amount of Teflon grease....comments welcome.

The aftermarket fitting suggested by Brian was the type of product I was chasing..if only they were made for the LP400.

[SamEEE]

You can have some off my shirt if you'd like. ;_;

[deadeyedick]

You can have some off my shirt if you'd like. ;_;

Does it pass the TT thread spec requirements for ap ?

[SamEEE]

I'm not sure. Free to a good home if you can get it out of my shirt.

[Brian Girling]

See:-

http://www.bestfittings.co.uk/shopexd.asp?id=339

This allows you to vent the system (after closing the cylinder valve), note the small hole in the end face which prevents the cylinder being depressed.

Great for Steyr users Brian, bot not much help for the OP with his FWB (unless they use the same adaptor).

I am not familiar with the FWB system, but if it uses a similar positioned valve then it is worth an email.