PCP AP Cylinder -- To Empty or Not?

philipnow · Post by **philipnow** » Wed May 02, 2007 10:41 pm

I would imagine this has probably been discussed many times, but my admittedly brief search did not yield a conclusive answer...

I shoot once or twice a week. Should I completely empty my LP@ Light's cylinders or not? Actually I've only been using one of them, and have never filled the other. I have been in the practice of shooting until the cylinder is halfway or two-thirds empty, then just leaving it that way until the next session at which time I just top it off. I read somewhere about perhaps the need to empty every now and then to purge possible accumulated water? Also, is it OK to leave a cylinder completely empty?

Thanks.

Philip

pgfaini · Post by **pgfaini** » Thu May 03, 2007 7:57 am

Before removable cylinders were the norm, I doubt anybody went to the trouble of purging their cylinders. Recently, I had to do it on the fixed cylinder on my Morini 162E in order to replace the filling seals, but I wouldn't want to have to do it again. I discharged air by "dry firing", until I was able to depress the pin on the schrader valve to completely empty it. I've also seen someone do the same by tapping the pin with a plastic mallet, but I don't think this was wise. After eight years of filling from SCUBA tanks, there was no evidence of any moisture present in my cylinder. Don't know what would be found in a cylinder filled with a hand pump, though.

Paul

RobStubbs · Post by **RobStubbs** » Thu May 03, 2007 3:38 pm

No need to empty them out just leave them as they are. If you use a hand pump then moisture may well become a problem and for that you need to drain out the pump itself. Dive bottles use dry air and shouldn't give you any problems with moisture.

Rob.

Tom Amlie · Post by **Tom Amlie** » Thu May 03, 2007 4:35 pm

It was my understanding that leaving them pressurized was better, since the (presumably) dry air under pressure in the tank would keep out the moist ambient air at atmospheric pressure (1 BAR). I know that when used scuba tanks are advertised sellers often make a point of noting that the tank was stored pressurized.

I guess if your not using commercially-supplied "dry" air there may be some merit to purging your cylinder.

JulianY · Post by **JulianY** » Thu May 03, 2007 11:49 pm

When I spoke to Harry Preston (styer uk) about keeping the empty for storage, I was told don't worie about it. Personally I keep both of min full, but rotate then each time. so befor a shoot i put the full one on and fill the empty.

I cant speak for morini, but i suspect it similar, for styer. I understand the correct way to empty one is to remove it from the gun, gently and slowly screw in the filling adapter until the air slowly starts to come out and then let it sit whilst it empties it self . gradually screw in the adapter more as the progress slows.

Pins and hammers are screaming for a break

JY

pgfaini · Post by **pgfaini** » Fri May 04, 2007 1:28 am

Julian, my Morini 162E being a fixed cylinder gun, your method of purging isn't relevant, but it aroused my curiosity. I know removeable cylinder guns have a projection in the recepticle for the cylinder, to depress the valve pin as the cylinder is screwed in, and let air into the guns measuring chamber. But I see no reason for this projection in the filling adapter, since when filling, air is moving from high pressure to low pressure, opening the spring loaded valve, which again closes when the pressure equalizes. This is how the schrader valve works on my Morini. Is the filling sequence different on a removable cylinder Steyr?

Paul

JulianY · Post by **JulianY** » Fri May 04, 2007 1:37 am

pgfaini wrote:Julian, my Morini 162E being a fixed cylinder gun, your method of purging isn't relevant, but it aroused my curiosity. I know removeable cylinder guns have a projection in the recepticle for the cylinder, to depress the valve pin as the cylinder is screwed in, and let air into the guns measuring chamber. But I see no reason for this projection in the filling adapter, since when filling, air is moving from high pressure to low pressure, opening the spring loaded valve, which again closes when the pressure equalizes. This is how the schrader valve works on my Morini. Is the filling sequence different on a removable cylinder Steyr?

Paul

Paul, What i'll do is photograph it all and add it to the wiki so you can see.
The old cylinders did mot a gauge in the and used a screw in gauge. The design of the fitting has not really changed My understanding is the the adapter is designed this way to take advantage of this for this purpose. unfortunately I wont be able to get to it for a few days. if i forget PM me

Julian

JulianY · Post by **JulianY** » Fri May 04, 2007 2:18 am

I have uploaded the picture of the fill adapter, as you will see the tip is flat to push the pin and there is a hole is the sided to let air in and out.

I just tried it and it works very easily. I would recommend that you hold the adapterclean cloth and it gets quite cold get quite cold . the whole operation only takes about 20 seconds

http://www.shootingwiki.org/index.php?t ... daptor.jpg

JY

David Levene · Post by **David Levene** » Fri May 04, 2007 2:59 am

The Morini and Steyr work in different ways.

On the Morini the valve is opened during the filling process purely by air pressure. You can therefore screw the filling adaptor on to the Morini cylinder without releasing any air from it.

On the Steyr the filling adaptor opens the cylinder's valve mechanically.

pgfaini · Post by **pgfaini** » Fri May 04, 2007 7:45 am

After looking at Julian's photo, and reading your post David, I see the difference. I would expect the O-ring seals before the valve is opened, and backing the fill adapter off before the valve closes allows the air to escape through the bleed hole that is meant to equalize the pressure before the unit is unscrewed completely.

I would imagine that on the Morini, when installing on the gun, the valve must also be opened mechanically.
Paul

philipnow · Post by **philipnow** » Fri May 04, 2007 4:02 pm

Thank you for all the answers to my question. I appreciate the generosity of knowledge. I won't bother emptying my cylinders, then.

Philip

John Ariani · Post by **John Ariani** » Fri May 04, 2007 6:42 pm

Thats the one thing I dislike about the new P 44. To empty the cyclinder one has to dry fire....about 300 times if it happens to be fairly full at the time.
My Morini (162EI) came with an valave adaptor which like the steyr - you just screw in and it allows the air to escape.

Fred Mannis · Post by **Fred Mannis** » Fri May 04, 2007 11:04 pm

John Ariani wrote:Thats the one thing I dislike about the new P 44. To empty the cyclinder one has to dry fire....about 300 times if it happens to be fairly full at the time.
My Morini (162EI) came with an valave adaptor which like the steyr - you just screw in and it allows the air to escape.

John, the P44 comes with an adapter that screws into the cylinder and depresses the valve, allowing the air to escape.

pgfaini · Post by **pgfaini** » Sat May 05, 2007 1:09 am

I hope never to have to replace the fill valve seals on my 162E again, but if I do, I'll probably turn a cap that will depress the valve pin when screwed on.

Paul

David Levene · Post by **David Levene** » Sat May 05, 2007 1:16 am

pgfaini wrote:I hope never to have to replace the fill valve seals on my 162E again, but if I do, I'll probably turn a cap that will depress the valve pin when screwed on.

Paul, do you know anyone with a 162*I. It should have come with a screw in "cylinder emptier". It might be worth trying on the 162E.

Nicole Hamilton · Post by **Nicole Hamilton** » Sat May 05, 2007 2:58 am

Most of the stress on a compressed air cylinder is going to be when the pressure changes (especially when it changes quickly) because that's going to be when it expands slightly as it's filled, then contracts slightly as it's emptied. At a static pressure, the metal is in a static state as well.

So, no, you should not discharge your cylinder any more than would normally occur in the course of ordinary use. Deliberately releasing all the air, then filling again from an empty state will only put extra stress on it, causing the metal to fatigue faster than otherwise.

pgfaini · Post by **pgfaini** » Sat May 05, 2007 7:36 am

Thanks David, I'll check this out. Save myself some machining. When I changed the seals, I thought about turning a short rod to fit inside the dust cap, to depress the pin, but decided not to, not wanting to strain the threads, due to the low strength of the aluminum it is made of.

Nicole, Your thoughts are noted. As a retired machinist/gunsmith, originally schooled in tool and die making, of which metalurgy is a part, I concurr. As I stated in my original post, I don't think it necessary to purge the cylinder routinely. I only did it in order to change the seals.

Paul

jipe · Post by **jipe** » Sat May 05, 2007 8:21 am

I have a question related to moisture when using an hand pump for filling the cylinder of AP.

I use since quite a long time now a Gehmann pump for filling the cylinders of my Steyr LP10.

On this pump there is a moisture evacuation srew. I have used that screw as recommended in the user manual of the pump several times but never seen any water nor even any moisture coming out.

Therefore my question: is moisture a real issue, did some of you had any issue with moisture especially for those (if any) using a pump to fill their cylinder ?

David Levene · Post by **David Levene** » Sat May 05, 2007 8:58 am

jipe wrote:Therefore my question: is moisture a real issue, did some of you had any issue with moisture especially for those (if any) using a pump to fill their cylinder ?

The early Steyr cylinders had a pressure indicating pip in the end. This was controlled by several steel springs inside the cylinder.

The day I first saw what had happened to those springs (rust) when the cylinders had normally been filled with a pump was the day I decided to change over to nice dry scuba air.

I know that the latest Steyrs have a gauge but I still don't like the idea of moisture when there isn't supposed to be any.

I am sure that the humidity where you live will have some effect but here in the UK moisture is definitely a problem.

John Ariani · Post by **John Ariani** » Sat May 05, 2007 6:55 pm

John, the P44 comes with an adapter that screws into the cylinder and depresses the valve, allowing the air to escape.[/quote]

Dill!!!!!
That's me!
I've had that all along Fred and on first galnce when getting the gun, thought it was a hard cover cyclinder end protector - sort of like hard version of the soft plastic one that also comes with the gun.
After your post and closer inspection - I see it's to release the air.
I feel like a real dumbo!! (and my wife is still laughing at me!!)

TargetTalk

PCP AP Cylinder -- To Empty or Not?

PCP AP Cylinder -- To Empty or Not?

Moisture

Re: Moisture