If a reservoir was filled or charged to its full level at sea level then transported to say the mountains in Colorado would it then be overcharged?
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Elevation effects on air rifle tanks
- Thread starter Willie14228
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The pressure would remain the same but the difference between it and atmospheric would be greater. The difference would also change as the barometric pressure changes !
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G
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Let's suppose you filled a cylinder to 207 BAR (3000 PSI) at sea level. That is 207 atmospheres. Now that is 207 atmospheres at sea lever or at any altitude; however, the pressure of the atmosphere does offset the internal pressure of the bottle, only slightly but it does never-the-less. If you then took that bottle to 27000 feet where the pressure was only about 5 PSI then you would effectively increase the pressure inside the bottle by 2/3 of one atmosphere, not enough to matter.
Now someone is going to jump in here and try to explain how the pressure inside the bottle does not change, and that is true; however the DIFFERENCE in pressure between the inside and the outside of the bottle DOES change.
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All pressures are differential, that is, inside pressure versus outside pressure. Outside pressure at sea level is 14.7 PSI. If you took your air gun into orbit in a non pressurized rocket, it would be like filling the tank 14.7 PSI higher while sitting on a beach. Or, like filling your 3000 pound rated tank to 3014.7 pounds of pressure. No harm, no foul, well within the safety margin of the tank. Changes in temperature makes a bigger difference in pressure, such as filling the tank in Antarctica in winter, then taking it to the Gobi desert in the peak of summer.
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If filling a reservoir by hand using a hand pump, would it require a longer time to fill (i.e. more pumps) at 7,000 ft (where I live) vs. sea level?
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Short answer, yes. At 7000 feet all pumps (which even include car engines) are less effective.
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I stick my small venture tank in my freezer for about 15minutes before I fill it , My Sheldon compressor fills it to 5000 psi,
Back in my office in a few days it shows 4800 psi, I tried this with out the freezer treatment and the tank read about 4400 psi after a day or so.
I do not do this with my great white as the tank is just to big,,,
Mike
Back in my office in a few days it shows 4800 psi, I tried this with out the freezer treatment and the tank read about 4400 psi after a day or so.
I do not do this with my great white as the tank is just to big,,,
Mike
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iride,
If the bottle was able to "hold" hold some of its cold and chill the air inside it, that could explain what you are seeing. Gas pressure and temp work like P1/T1 = P2/T2 so if the bottle and the air in it were chilled the whole time it filled, you'd have a pressure increase once it got warm. Or the other way around. If you started with a room temp bottle and filled it, it would have to get hotter. The bottle and gas would both be hotter than room temp at the end of the pumping. So when the bottle and gas in it cool back down to room temp the pressure drops.
If you filled that bottle inside the freezer at it and it was able to keep the air going in chilled to 0F and you stopped filling around 4300 psi, once you removed it from the freezer and it got back to room temperature the gauge would read around 5000 psi.
If the bottle was able to "hold" hold some of its cold and chill the air inside it, that could explain what you are seeing. Gas pressure and temp work like P1/T1 = P2/T2 so if the bottle and the air in it were chilled the whole time it filled, you'd have a pressure increase once it got warm. Or the other way around. If you started with a room temp bottle and filled it, it would have to get hotter. The bottle and gas would both be hotter than room temp at the end of the pumping. So when the bottle and gas in it cool back down to room temp the pressure drops.
If you filled that bottle inside the freezer at it and it was able to keep the air going in chilled to 0F and you stopped filling around 4300 psi, once you removed it from the freezer and it got back to room temperature the gauge would read around 5000 psi.
Upvote 0