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Posted: Sat Feb 18, 2012 7:24 pm |
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MikeSD |
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Joined: 05 Feb 2012 |
Posts: 31 |
Location: Washington State, USA |
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So, what's the real story on how much pressure a PCP gun should lose.
The folks where I bought my pistol said the gun should hold air "indifinitely". I'm not a strong believer that "indefinitely" is accurate. Even my car tires eventually need air.
I have a Benjamin Marauder pistol and it was leaking 200psi every half hour. That was not good and I returned it. The replacement was filled 2 days ago and hasn't budged. So it's holding air quite good.
I also have a Benjamin Marauder rifle. I filled it with air about 7 hours ago, to do a similar test and after about 7 hours, it's down a little under 200psi. This isn't much and I'm going to continue to watch this, to see if it's more than just temperature variation.
But how long should a PCP gun, actually retain air? Is it really indefinite? At what rate is the loss of air unreasonable, in your view? |
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Posted: Sat Feb 18, 2012 7:28 pm |
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rsterne |
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Location: Coalmont, BC |
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It could easily have lost 200 psi just from cooling after filling.... Most PCPs do, indeed, hold air "indefinitely".... I have had them that show no appreciable air loss over months of storage....
Bob |
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_________________ Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal: Too many to count! |
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Posted: Sat Feb 18, 2012 7:29 pm |
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radar |
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Joined: 13 Nov 2011 |
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Location: Des Moines, Iowa, USA |
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All I know is my Sam Yang and Discovery both hold for weeks and weeks of inactivity. No movement on the gauges at all. I think if the seals are good, maybe lubed with silicone grease and no dirt speck on the exhaust valves, why not?
I haven't had them long enough to know, but lots of guys I read about have pressure after 2-3 years when they get it out to shoot it. |
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_________________ It's never too late to have a happy childhood. |
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Posted: Sun Feb 19, 2012 9:00 am |
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MikeSD |
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Joined: 05 Feb 2012 |
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Location: Washington State, USA |
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rsterne wrote: |
It could easily have lost 200 psi just from cooling after filling.... Most PCPs do, indeed, hold air "indefinitely".... I have had them that show no appreciable air loss over months of storage....
Bob |
It's not a loss because of cooling after filling. I was careful to fill it slow and wait for cooling and then topped it off again. It appears to have a very slow leak. This is bothersome because this is the second Benjamin that I have bought that had a leak. 2 for 2 isn't a good statistic.
My first was a couple of weeks ago. It was the Marauder pistol that was leaking about 200psi every 20 minutes. If I loaded it in the morning, it would be nearly empty by the end of the day. That was too fast. So I returned it and asked them to test one and replace it with one that didn't leak. I tested the replacement and the leak is gone. I filled it to 2900psi two days ago and it's still exactly where I left it.
The second one arrived about 3 days ago. I filled it and repeated the test, making sure the air had cooled and topped it off. It is now 20 hours since I filled it and it's down a bit over 400psi. At 9 hours it was 200psi down. So it looks like it loses about 200psi about every 9 hours + or -. It's not bad but if it should hold air indefinitely, it's a problem. I can live with this slow leak so maybe I'll just keep it and tinker with it.
BTW, I had both guns filled at the same time. This was to check for temperature variations. One is solid and the other leaks slooooly?
Oh well, perhaps I'll get some of that silicone lube and just pull it apart and reseat everything.
Would you worry about your gun if it had a leak at 200psi every 9 hours? |
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Posted: Sun Feb 19, 2012 11:42 am |
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rsterne |
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Location: Coalmont, BC |
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Depends on how much you shoot.... If daily, not too much of an issue, fill before shooting, same if hunting.... If, however, you rely on quick access for pest control, and the guns sits for a week in between, then it definitely needs fixing....
Bob |
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_________________ Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal: Too many to count! |
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Posted: Sun Feb 19, 2012 12:31 pm |
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radar |
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Location: Des Moines, Iowa, USA |
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^^^ +1.
I prefer to store them under partial pressure to keep dirt out and the seals set, but If I can't--I don't worry if they are in a dry place. Mostly need the air for one day of hunting. You can probably fix this or make it much better with a little clean and lube though. |
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_________________ It's never too late to have a happy childhood. |
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Posted: Sun Feb 19, 2012 2:13 pm |
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MikeSD |
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Location: Washington State, USA |
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Thanks, I'll probably just keep it and not send it back. I suspect I can make it tight and I really should learn how to maintain these. I'll just get some silicone and tear it apart someday, when I get the time.
I was digging in my closet today and came across a couple of old air guns. I'm going to start a new post on those. They aren't very interesting but they were the first I owned and still have them. |
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Posted: Sun Feb 19, 2012 7:26 pm |
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radar |
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Location: Des Moines, Iowa, USA |
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MikeSD wrote: |
...aren't very interesting but they were the first I owned and still have them. |
If you are bored with those closet finds, I'll PM you my mailing address! |
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_________________ It's never too late to have a happy childhood. |
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Posted: Mon Feb 20, 2012 1:05 pm |
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MikeSD |
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Location: Washington State, USA |
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Silicone grease?
I did a search of "silicone" on Pyramyd Air and only came up with one product which was an "oil" for the chamber. There was another product of silicone grease for a hand pump. Another product said not to use on PCP guns. Some silicone products apparently aren't recommended.
I guess I'll try to get pure silicone grease. What specific product would you suggest for sealing a leaking o-ring? I have seen some from scuba shops. I guess that might work. |
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Posted: Mon Feb 20, 2012 9:50 pm |
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radar |
Silver Status Member |
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Joined: 13 Nov 2011 |
Posts: 1138 |
Location: Des Moines, Iowa, USA |
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MikeSD wrote: |
Silicone grease?
I did a search of "silicone" on Pyramyd Air and only came up with one product which was an "oil" for the chamber. There was another product of silicone grease for a hand pump. Another product said not to use on PCP guns. Some silicone products apparently aren't recommended.
I guess I'll try to get pure silicone grease. What specific product would you suggest for sealing a leaking o-ring? I have seen some from scuba shops. I guess that might work. |
That Hill hand pump grease from Pyramyd is what I use. If you can be sure it's 100% silicone, I believe you can use plumber's waterproof grease that is used for lubing the stems on water valves. Hardware store item. I've read a lot of airgunners use that but I've never tried it. |
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_________________ It's never too late to have a happy childhood. |
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Posted: Mon Feb 20, 2012 10:22 pm |
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SMP |
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_________________ Sean
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| | | | | | | | | Loss of Air Pressure? | | | | | |
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