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Air Pumps and Cylinders question
Posted: Sun Dec 07, 2008 5:44 pm
by higginsdj
I got to shoot my new Steyr LP 10 yesterday but I had 'issues' filling the cylinder with the FX air pump. The pump instructions stated that I had to open the bleed valve on the pump before removing the cylinder but by doing so, the cylinder emptied its contents in less than 1/2 second......
So, it this a language translation issue or am I missing something?
Yes I did this a few times - well I ended up pumping up the cylinder 4 times - before just ignoring the advice and just unscrewed the cylinder from the pump.
Cheers
David
Posted: Sun Dec 07, 2008 7:24 pm
by tenex
Hi David,
My friend has an LP-10, and he unscrews the tank just enough to close the tank valve (not enough to let the air escape in the hose). I'd take a turn or two off the cylinder, then open the pump bleed. If you just unscrew the cylinder, the air in the pump will blow by the cylinder seal, potentially damaging it.
The fill adapter on my Pardini doesn't depress the valve, so I can just open the pump bleed. The down side for me is I need to overcome the pressure needed to open the valve, and pump to a little higher pressure.
Steve.
hey
Posted: Sun Dec 07, 2008 7:28 pm
by laxratnd
If i am correct on the steyr, the fill adapter pushed the valve pin on the cylender open when you screw it in. So after you pump the tank and then open the release valve you will loose all your air. Unscrew the cylender and then release the valve.
lax
Posted: Sun Dec 07, 2008 7:55 pm
by higginsdj
Thanks guys. So the message is disengage first then open the bleed before disconnecting - got it.
Cheers
David
Posted: Mon Dec 08, 2008 10:22 am
by jipe
higginsdj wrote:Thanks guys. So the message is disengage first then open the bleed before disconnecting - got it.
Cheers
David
The reason to open the bleed is to remove any moisture generated by the compression of the humid air. As stated by the laxratnd, for Steyr cylinder, screwing it onto the adapter maintain the valve open => if you open the bleed screw, the cylinder becomes empty (what is not the case for other brand, Anschutz rifle cylinder for instance).
The process for Steyr cylinder is to fill the cylinder, then sligthly+shortly open the bleed screw (really a little) to let any moisture escape, by doing some air will be lost => the pressure will drop (a little because the bleed screw is only slightly+shortly opened) and then pump a couple of stroke to complete the pressure to 200 bar.
Posted: Mon Dec 08, 2008 10:49 am
by OzzieM
Jipe[/quote]
The process for Steyr cylinder is to fill the cylinder, then sligthly+shortly open the bleed screw (really a little) to let any moisture escape, by doing some air will be lost => the pressure will drop (a little because the bleed screw is only slightly+shortly opened) and then pump a couple of stroke to complete the pressure to 200 bar.[/quote]
Right. The trick is to close the bleed valve lightly before pumping up the cylinder. This allows you to 'slightly and shortly' open the bleed screw.
OzzieM
Posted: Mon Dec 08, 2008 4:02 pm
by higginsdj
Hmmmm... As moisure is considerably denser than air, if the bleed value is opened only enough to let a tiny amount of air leave, how much moisture will escape?
In theory, as the cylinder is upside down, any moisture should run down out of the tube into the adapter/pump - or is the idea to have the escape of air force any moisure into the adapter/pump prior to disengaging? But then the air is warm/hot so the moisture could be gaseous so one should wait until the cylinder is well cooled before venting/disengaging...
Or am I overthinking this?
Posted: Mon Dec 08, 2008 10:47 pm
by pilkguns
On the Steyr cylinders, unscrew the cylinder 1/2 to 3/4 of a turn, this closes the cylinder valve. then open your bleed screw on your pump
Posted: Tue Dec 09, 2008 11:16 am
by Fred Mannis
higginsdj wrote:Hmmmm... As moisure is considerably denser than air, if the bleed value is opened only enough to let a tiny amount of air leave, how much moisture will escape?
In theory, as the cylinder is upside down, any moisture should run down out of the tube into the adapter/pump - or is the idea to have the escape of air force any moisure into the adapter/pump prior to disengaging? But then the air is warm/hot so the moisture could be gaseous so one should wait until the cylinder is well cooled before venting/disengaging...
Or am I overthinking this? Definitely :-) Follow Scott's advice.
Posted: Tue Dec 09, 2008 2:17 pm
by peepsight
Is it some thing to do with condensation forming on the inside of the cylinder due to it warming up when you fill it from a scuba tank and when it goes cold again?
Peeps
Posted: Wed Dec 10, 2008 3:25 am
by RobStubbs
peepsight wrote:Is it some thing to do with condensation forming on the inside of the cylinder due to it warming up when you fill it from a scuba tank and when it goes cold again?
Peeps
Nope, ;)
Air condenses on a cold surface plus scuba air is dried.
This thread is talking about the hand pumps, not scuba tanks. In this case the water vapour 'condenses' because of the increased pressure. Air can only hold so much water vapour per cm3 and compressing it goes over that limit and forces it to condense.
Rob.