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Air Gun Home Forum Index » Rifles » Loss of Air Pressure?    View previous topic :: View next topic  Loss of Air Pressure?   Posted: Sat Feb 18, 2012 7:24 pm MikeSD Member Joined: 05 Feb 2012 Posts: 31 Location: Washington State, USA 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?   Posted: Sat Feb 18, 2012 7:28 pm rsterne Moderator Joined: 15 Jan 2008 Posts: 2998 Location: Coalmont, BC 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 _________________ Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! Airsonal: Too many to count!   Posted: Sat Feb 18, 2012 7:29 pm radar Silver Status Member Joined: 13 Nov 2011 Posts: 1138 Location: Des Moines, Iowa, USA 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. _________________ It's never too late to have a happy childhood.   Posted: Sun Feb 19, 2012 9:00 am MikeSD Member Joined: 05 Feb 2012 Posts: 31 Location: Washington State, USA 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? _________________ .22 Benjamin Marauder pistol .22 Benjamin Marauder rifle http://www.msdsite.com/air/   Posted: Sun Feb 19, 2012 11:42 am rsterne Moderator Joined: 15 Jan 2008 Posts: 2998 Location: Coalmont, BC 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 _________________ Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! Airsonal: Too many to count!   Posted: Sun Feb 19, 2012 12:31 pm radar Silver Status Member Joined: 13 Nov 2011 Posts: 1138 Location: Des Moines, Iowa, USA ^^^ +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. _________________ It's never too late to have a happy childhood.   Posted: Sun Feb 19, 2012 2:13 pm MikeSD Member Joined: 05 Feb 2012 Posts: 31 Location: Washington State, USA 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. _________________ .22 Benjamin Marauder pistol .22 Benjamin Marauder rifle http://www.msdsite.com/air/   Posted: Sun Feb 19, 2012 7:26 pm radar Silver Status Member Joined: 13 Nov 2011 Posts: 1138 Location: Des Moines, Iowa, USA 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! _________________ It's never too late to have a happy childhood.   Posted: Mon Feb 20, 2012 1:05 pm MikeSD Member Joined: 05 Feb 2012 Posts: 31 Location: Washington State, USA 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. _________________ .22 Benjamin Marauder pistol .22 Benjamin Marauder rifle http://www.msdsite.com/air/   Posted: Mon Feb 20, 2012 9:50 pm radar Silver Status Member Joined: 13 Nov 2011 Posts: 1138 Location: Des Moines, Iowa, USA 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. _________________ It's never too late to have a happy childhood.   Posted: Mon Feb 20, 2012 10:22 pm SMP Silver Status Member Joined: 04 Feb 2011 Posts: 1183 Location: Just south of "Out There"- Land O Lakes Ontario The Hill Pump grease is available at pyramid http://wop.pyramydair.com/s/a/Hill_Hand_Pump_NLGI_2_Silicone_Grease_40g/3888 Divers grease from your local dive shop Dow Corning High Vaccum Silicone grease if your an industrial guy Plumbers grease(oring grease) from the Do-it store. comes in a lip balm sized round flat container-only the one that says pure silicone _________________ Sean Loss of Air Pressure?     Air Gun Home Forum Index » Rifles You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum All times are GMT - 5 Hours   Page 1 of 1   All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First  Select a forum Main Forums----------------AirGunHome Q&AGeneral Air Gun Questions and TopicsPicture GalleryTarget Shooting: Casual, Fun and CompetitionHunting, Pest Control, Varminting People/Events/Airgun Issue Discussion----------------Introduce YourselfThe BS TopicClubs/Events/Regional/Political Airgun Issues Maintenance, Modification and Reviews----------------RiflesPistolsAntique, Collector and Novelty AirgunsBB GunsPellets/AmmoOpticsAccessoriesAirgun Smithing Buy, Sell or Trade Forums----------------For SaleWant to Buy   Note: If you are seeing "Please enter your username and password to log in." 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