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"In the world of spuds today"

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Unread postAuthor: JDP12 » Thu May 15, 2008 10:42 pm

MrCrowley- possibly the pump gauge measures the pressure the pump creates, but do to larger or smaller chamber volumes, your chamber pressure is different?
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Unread postAuthor: MrCrowley » Thu May 15, 2008 10:46 pm

Oh so you're saying the pump measures the pressure going through the gauge but once it goes through the checkvalve after the gauge, the pressure equalizes with the chamber, which has a larger volume so the pressure drops down.

But because of the checkvalve, the pump gauge still reads what it put out, not the final PSI....

Makes sense, no?
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Unread postAuthor: JDP12 » Thu May 15, 2008 10:51 pm

yea thats what i think, but i've never used a pump like that, but to me it seems like what would make the most sense.
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Unread postAuthor: GalFisk » Fri May 16, 2008 3:34 am

That explanation does not make sense, the check valve should open as soon as the pressure inside the pump exceeds the chamber pressure, keeping the pump pressure from rising any further.
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Unread postAuthor: Carlman » Fri May 16, 2008 3:56 am

ok on your pump valve chuck there is a chrome button, it is a pressure bleed valve. pump up one of your guns to the suposed 260psi as shown on your pump, now press that chrome button. do they go down at the same rate or do they differ?
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Unread postAuthor: MrCrowley » Fri May 16, 2008 4:28 am

GalFisk wrote:That explanation does not make sense, the check valve should open as soon as the pressure inside the pump exceeds the chamber pressure, keeping the pump pressure from rising any further.
Yeah sorry I realised I messed that up but I didn't change it because I fixed it in another thread.

I think my gauge has it's own checkvalve or something. That would explain it. The pump would push air into the pressure gauge and into the chamber, but since the gauge pressure doesn't equalize with the larger chamber volume, the pressure is far higher...

Or is there another explanation that you think might be it?

Edit: Carlman,

Not sure, haven't tried. Because most of the time I used a threaded schrader in a female Quick Connect and attached the pump to the cannon with the male QC from the gun. That way I can keep my QC's on all the cannons instead of changing them to schraders.

And since a female QC acts like a check valve, depleating the pressure from the pump wouldn't effect the chamber pressure.
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Unread postAuthor: VH_man » Fri May 16, 2008 5:51 am

in the world of spuds today.... i had an ingenious idea in my sleep last night....

AIR ENGINE!!!! basically like one of those air-hogs engines, except scaled up for use in larger items, such as go-karts and things.

im going to begin construction once i have money. im going for a single cylinder just to start...... someday ill go as bodacious as making a radial engine.........
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Unread postAuthor: MrCrowley » Fri May 16, 2008 11:40 pm

ITWOST, figured out the pump problem.

For some reason the schrader fill thing from the pump had a bit of teflon tape in it and stopped it from seating properly.

Found it out when I filled a vessel to 150psi, then emptied it via the bleed switch and the gauge said it still had 50psi in the vessel :lol:

Did a few shots with Slim Biggins at 200psi. The QEV held up fine. I might take it up to 220psi. Paintballs at 200psi destroy 1/2" plywood :)

I also took my co-ax up to 260psi but the JB-Weld started to leak, so that's getting fixed. Should be fine after that as i've had other JB-Weld hold higher. Did get a few test shots in though, i'd guess the metal BB's are going around 900-1000fps. I might GGDT it and find out.
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Unread postAuthor: SpudFarm » Sat May 17, 2008 11:14 am

GalFisk wrote:That explanation does not make sense, the check valve should open as soon as the pressure inside the pump exceeds the chamber pressure, keeping the pump pressure from rising any further.

finaly he messed himself to make a post again :D:D
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Unread postAuthor: Carlman » Sun May 18, 2008 5:00 am

MrCrowley wrote:ITWOST, figured out the pump problem.

For some reason the schrader fill thing from the pump had a bit of teflon tape in it and stopped it from seating properly.

Found it out when I filled a vessel to 150psi, then emptied it via the bleed switch and the gauge said it still had 50psi in the vessel :lol:

Did a few shots with Slim Biggins at 200psi. The QEV held up fine. I might take it up to 220psi. Paintballs at 200psi destroy 1/2" plywood :)

I also took my co-ax up to 260psi but the JB-Weld started to leak, so that's getting fixed. Should be fine after that as i've had other JB-Weld hold higher. Did get a few test shots in though, i'd guess the metal BB's are going around 900-1000fps. I might GGDT it and find out.


i have taken my 1/4" diaphragm QEV to 300psi just fine so i reckon it can take it just fine, mines a SMC, yours is too, no?
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Unread postAuthor: MrCrowley » Sun May 18, 2008 5:04 am

Nah, mines an American Detrol.

British QEV's have also handled 300psi, but i'm not sure if anyones tested the American Detrols at those pressures before.

Edit: Oh and I took it up to 240psi today. A paintball at 240psi split in half 3/4" thick wood that was a meter long, from top to bottom. The only reason it was still together was because it was braced at the bottom.
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Unread postAuthor: al-xg » Sun May 18, 2008 6:03 am

British QEVs have handled 850psi :)
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Unread postAuthor: biged » Mon May 19, 2008 5:07 am

Room temperature was 68 degrees, gas was CO2.
Both metal QEV's were rated for 150 psi.

Both developed micro leaks using blue micro leak detector (soap & water).
1/4" QEV to 760 psi / 52.4 Bar
1/2" QEV to 620 psi / 42.7 Bar

Both maxed out at with audible hissing / leaking.
1/4" QEV to 830 psi / 57.2 bar
1/2" QEV to 810 psi / 55.8 bar

I can only guess that repeated over pressurization will cause the seals to fail more prematurely.

///ed///
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Unread postAuthor: MrCrowley » Mon May 19, 2008 5:52 am

Thanks for that and because CO2 is slighter denser then air, air would leak at a lower pressure right?

It also seems the bigger the valve, the lower the pressure it leaks at. So 3/4" QEVs would leak around ~790 PSI, though that could very well be much different.

What brand of QEVs were tested as well?
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Unread postAuthor: al-xg » Mon May 19, 2008 10:33 am

There might be micro leaks on my QEV, but no audible leaks, I use high pressure air regulated to 60bar/850psi.

What seals do you mean ?
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