Compressor gauge or airgun gauge?

[keninsc]

New at this~~~I have a question.
I went to charge my rifle (new) Hatsan Flash with the typical Chinese A3 compressor I decided to buy.
I am sure just how accurate the gauges are on this equipment but setting the compressor to shut down at 2000#, the rating of the rifle, the gauge on the rifle only reflected a charge of just over 1000#.
So I turned the compressor back on, setting the auto shutoff for 2500# and when it stopped the rifle indicated a full/ideal 2000# charge.
So do I go by the rifle gauge or the compressor?

 

[sb327]

You might add a picture of both gauges, that way, no assumptions can be made to what type each has.

Typically, a compressor gauge is more accurate.

Dave

 

[keninsc]

OK, not sure what you can learn looking at them, but here they are. The focus is a bit of/close for the camera.
Also, the rifle gauge did not stick at any point and had a very smooth and gradual climb.

 

[Stan’s boy John]

I was a Metrology Engineer for Lockheed for 37 yrs and can tell you those gauges are for reference only. Not accurate at all.

 

[ToddGeddes63]

I go by the gauge on my rifle. I figure that the air is going into the gun and that is what I need to be concerned with. my compressor doesn't have auto-shutoff either.

 

[jarmstrong]

some guns fill slower than what the compressor puts out
my coltri always has higher gauge reading than my Zbroia Sapsan gauge, I fill to the gun's gauge.
the sapsan has a restrictive air passage going into the tank, from the fill port
on my Kozak, HW110 and Gamo the gauges are pretty close to the compressor output

 

[Stan’s boy John]

I go by the gauge on my rifle. I figure that the air is going into the gun and that is what I need to be concerned with. my compressor doesn't have auto-shutoff either.

That’s what I’d do too. No way I’d trust that Chinesium gauge in the compressor.

 

[ToddGeddes63]

Something else to keep in mind this time of the year is temperature. If you fill the pcp inside and take it out into the cold, the pressure will be less. My first winter I thought I had A small leak, I would fill to 3000 and when I got to the shooting destination, the pcp was at 2800 psi. And so, if you fill the pcp outside in cold conditions and then take the pcp into a warm environment the pressure will increase.

 

[keninsc]

Stan's Boy, I also worked in a type 2 government Cal Lab for a few years and then on to electronics on the nuclear subs until early retirement forced by a shipyard closure.
I kind of figured that the gauges were pretty much garbage.
So, I think I will fill the rifle using its gauge and hope I don't damage it.

 

[sb327]

That’s what I’d do too. No way I’d trust that Chinesium gauge in the compressor.

vs the Chinesium gauge on the gun?

 

[Stan’s boy John]

vs the Chinesium gauge on the gun?

Oh they’re both junk don’t get me wrong. If the gun blows up then you have some recourse. I saw a post here where someones bottle exploded. Probably from relying on one of these gauges. It’s a crap shoot. If both gauges differ you have a problem with one of them.

 

[Stan’s boy John]

New at this~~~I have a question.
I went to charge my rifle (new) Hatsan Flash with the typical Chinese A3 compressor I decided to buy.
I am sure just how accurate the gauges are on this equipment but setting the compressor to shut down at 2000#, the rating of the rifle, the gauge on the rifle only reflected a charge of just over 1000#.
So I turned the compressor back on, setting the auto shutoff for 2500# and when it stopped the rifle indicated a full/ideal 2000# charge.
So do I go by the rifle gauge or the compressor?

At best those gauges are +/-3% of full scale. Some have an accuracy wider than that. Add to that the fact you’re looking at two gauges the uncertainty doubles to 6%, perhaps more. I doubt the gauges in your BB gun even has a stated accuracy. We wouldn’t even calibrate those at Lockheed. We found the best pressure gauges were made by Wika.

 

[Stan’s boy John]

Stan's Boy, I also worked in a type 2 government Cal Lab for a few years and then on to electronics on the nuclear subs until early retirement forced by a shipyard closure.
I kind of figured that the gauges were pretty much garbage.
So, I think I will fill the rifle using its gauge and hope I don't damage it.

I am familiar with the SWPAC facility at Silverdale and SWLANT

 

[JimNM]

For best safety margin, go with the one that reads the highest.

If it was mine, I would go by the reading on the gun. My YH gauge is never consistent against the gauge on my scba or my guns.

 

[Sodbuster]

So, would you trust this gauge? Is this accurate enough to use for testing other gauges, put a foster on it and check tank pressures?

 

[sb327]

I would trust it to run a check on the other gauges.

Dave

 

[rcs9250]

One other option. Buy a decent gauge. I know everybody leans to glycerine filled, they’re nice but not absolutely necessary. A 1/8 NPT male thread on gauge and a male and female Foster with 1/8 NPT male thread and a 1/8 NPT high pressure tee (minimum 5000psi). You won’t find any of that at Home Depot or Lowes. Because they are 1/8 NPT fittings there’s very little volume consumed, assuming you are filling from portable compressor or CF tank. Just hook this up inline either at your gun (less vibration) or at compressor. Now you can be confident of psi.
I didn’t have a tee so I drew it into photo.

 

[Stan’s boy John]

So, would you trust this gauge? Is this accurate enough to use for testing other gauges, put a foster on it and check tank pressures?View attachment 337866

The scale is way too high on that gauge.
Just spit balling, but I would try to find a three way tee and a gauge (possibly electronic accurate to +/-0.5% FS) and put this between the compressor and the gun. I’m not sure what thread they use on all this stuff.

 

[Stan’s boy John]

The risk is that now you’re like a man with three wrist watches. Never sure what time it is.

 

[keninsc]

I am familiar with the SWPAC facility at Silverdale and SWLANT

And my wife and I worked at Mare Island Naval Shipyard in Vallejo, CA until its closure notice came down in 1993. Mostly fast attack Los Angeles Class subs were build and overhauled but we did get some Ballistic Missile types at times with an occasional surface ship under our nuclear licensing.
I took early retirement otherwise they wanted to send most electronics types to King's Bay. No thanks.