Author Topic: Accuracy of Airgun and Air Tank Gauges  (Read 2133 times)

steveoh

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Accuracy of Airgun and Air Tank Gauges
« on: May 18, 2016, 09:56:00 AM »
Just picked up my AirHog tank from Vallejo Fire Extinguisher.  It's the big tank, and so far since October of last year has treated me right.  I'm much happier not pumping up my 909 and Sumatra, thank you very much.

The gauges on the 909, Sumatra and AirHog all seem to disagree. The owner of the Vallejo Fire Extinguisher told me this morning that the gauge on the AirHog is 200psi too low.  ???   This means I've been potentially overfilling my air guns. This does not at all make me happy.

Any thoughts about what is a reasonable amount of accuracy the AirHog gauge should be giving vs the accuracy of the gauges of the Sam Yang-a-do-dah-day airguns?

I'm willing to upgrade to better quality and accuracy gauges, especially in the AirHog. I'd thought that out of the three it would be the most accurate, but I now have doubts.

Steveoh


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wilsonj1018

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Re: Accuracy of Airgun and Air Tank Gauges
« Reply #1 on: May 18, 2016, 10:04:01 AM »
200 psi isnt a huge deal. buy a decent gauge and replace it if it bothers you. find what the guns like to be filled too in the shot string and mark the gun gauge with a sharpie. thats what ive always done. it cleans off with alcohol if you re tune it.
Josh
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clgraham82

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Re: Accuracy of Airgun and Air Tank Gauges
« Reply #2 on: May 18, 2016, 10:34:06 AM »
The gun gauges are probably off 200 in the other direction so you're probably right on  ;)

I'd give Airhog a call they are great folks willing to help out with their products.

I also rarely look at my gun gauges and just go off shot count once they've been chronied.

grumpy

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Re: Accuracy of Airgun and Air Tank Gauges
« Reply #3 on: May 18, 2016, 11:41:28 AM »
How do you know its not the fillers gauge that is off.
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steveoh

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Re: Accuracy of Airgun and Air Tank Gauges
« Reply #4 on: May 18, 2016, 12:21:02 PM »
How do you know its not the fillers gauge that is off.

That's a good question, and one that occurred to me.  He claims he has a super accurate high dollar gauge on his fill station, and is certified... what ever that means.

  • Benicia, California
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Alan

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Re: Accuracy of Airgun and Air Tank Gauges
« Reply #5 on: May 18, 2016, 12:48:35 PM »
I wonder about that too. It isn't like you can use a tire gauge's big brother, so you have to assume the gauges are close, but no cigar!

Not to rob a thread, but even the shutoff pressure switches (Freedom8 in this case) seem to vary way more than they should (±200 pounds). But is it the switch, or the gauge?
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Alan

I have an Omega compressor. If you're a fellow Guild member, and you pass through Roswell, NM, I'll fill your portable tank as a courtesy.

grumpy

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Re: Accuracy of Airgun and Air Tank Gauges
« Reply #6 on: May 18, 2016, 03:21:54 PM »
Tanks get hot when filled. They will drop PSI when cooled off. I never trust a guns gauge. Go by your tank. Only other thing I can say is if you want spot on measurements get a digi gauge.
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steveoh

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Re: Accuracy of Airgun and Air Tank Gauges
« Reply #7 on: May 18, 2016, 03:45:12 PM »
The guy I use says to leave the tank with him, as the first fill will be off as the tank cools down. He tops it off, and I come get it.


Tanks get hot when filled. They will drop PSI when cooled off. I never trust a guns gauge. Go by your tank. Only other thing I can say is if you want spot on measurements get a digi gauge.
  • Benicia, California
Quackenbush .58 Outlaw
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Vallejo Ferry Schedule
Sam Yang 909s .45
Sam Yang Sumatra .25
RWS Diana 350Magnum Compact Pro .22
QB-79 .177
Crosman 1322
Crosman 1377 - HoRodded 10 FPE
Diana Model 27 (childhood airgun)
Tolman Skiff
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Alan

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Re: Accuracy of Airgun and Air Tank Gauges
« Reply #8 on: May 18, 2016, 03:49:49 PM »
Grumpy, I agree. However... If you believe the tank gets hotter as you fill it (it obviously should), then as it cooled the pressure measurement should go down. But what if it goes up?

I mentioned elsewhere, the pressure switch on my Freedom8 is a bit flaky. One time it will shut off correctly, sometimes too low, and sometimes to high. When it shuts off low, I wait for about an hour, and low and behold, it will fill the tank up a few hundred pound higher (the switch is apparently a microswitch, so I have to bled off a few pounds to get it to restart filling). From my perspective, this is not a good scenario.

All this said, if I set the cutoff at say 4,800 or a bit higher, it seems like the repeatability is better. Based on all of this, I'm just leery of anything pressure-wise when it is related to airguns. So, I just sit there and watch the darn pump to make sure I don't burst a pressure disc. Drat!
  • Roswell, New Mexico
Alan

I have an Omega compressor. If you're a fellow Guild member, and you pass through Roswell, NM, I'll fill your portable tank as a courtesy.

sixshootertexan

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Re: Accuracy of Airgun and Air Tank Gauges
« Reply #9 on: May 18, 2016, 05:18:09 PM »
I'm sure his gauge is NIST certified being that he is a inspector. The gauges I've looked at that are NIST certified range from +/- .05% to 2%.

Is the airhog gauge the one with the logo on it? If so upgrade to a Wika. Airhog sells them for $38
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ShakySarge

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Re: Accuracy of Airgun and Air Tank Gauges
« Reply #10 on: May 19, 2016, 04:41:04 AM »
I have found that the non liquid filled gauge that came with my AirHog is 200psi low as well. My plan is to purchase a new gauge when possible and simply replace it. Until then, I rely on my quality gauge on the bottled marauder to tell me what 3000psi is and have it marked.

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grumpy

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Re: Accuracy of Airgun and Air Tank Gauges
« Reply #11 on: May 19, 2016, 04:47:57 AM »
Guild member Rdsail found a great deal couple years ago on a Digi gauge. Wished I got one back then.
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