PCP Air Tube and Remaining Air

I use in-line gauges on my filling setup. Something like -this- with related fittings.

If you're running a pump, there should be a gauge on that as well. 

You can tell your low end by shooting a shot string from full pressure. Fill your gun up, count your shots/mags until your point of impact drops. Take off about 5-10 shots and that's how many shots you have until it's time to refill. 

It's interesting that a PCP gun does not have a pressure gauge. What model is it?
Tom

if your using an air pump is would say that's the best way as the hose has to pressurize to the guns current psi before it able to let more air into the tube
​but with a the guppy I couldn't tell you

I thought as soon as you hook the gun to the tank the gauge on the tank will go fast to the amount in the gun then slowly start filling from there ....just zap it with air then close the tank for a rough idea.

"rwsmike"I thought as soon as you hook the gun to the tank the gauge on the tank will go fast to the amount in the gun then slowly start filling from there ....just zap it with air then close the tank for a rough idea.

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Yup, this is another easy way to tell where you're at. With my rifles, I can hear a "click" from the one way valve. That's the point at which when the pressure in the filling hose overcomes the remaining pressure in the bottle. 

.........I just took a look at the Guppy and see what you're talking about. You've only got one gauge, and it shows what your fill bottle pressure is at. Since you do not have a gauge on your rifle, I think an In-line gauge and related fittings like the one I linked above would be an answer. You can also give Joe a call and he should be able to help you out as well. Currently, I don't have an answer as to how you could tell, with any accuracy, what your pressure is at. 
The idea that I quoted above would only work with an in-line gauge. 
I think you could get away with adding an in-line gauge for under $50. You could also use a regulator system like I do but that's going to set you back ~$400ish and would be better utilized on a large bottle.
This next idea would be a waste of air but it would guarantee you wouldn't be over 230b. Bleed your guppy bottle down to about 240-250b (wear ear protection), fill your rifle. You're fill bottle should drop down to about 230-220 on the first fill. Subsequent fills will be less and less bar. Since it's a guppy you're going to go through air pretty quick. 
The 240-250 is a guess since I gave my Air Venturi to someone else to use. Maybe there's someone that uses them more often and can chime in on a more precise starting point that will conserve the most air yet keep you at around 230 for that first fill. 
Tom

Tom the Guppy can be purchased with two gauges as an option. One shows tank pressure and one shows fill pressure. Just hook to the gun and as others have suggested crack valve till the gun's check valve clicks. Close valve and read the pressure. The reading is approximately what is in the gun cylinder / reservoir.

Thurmond

@T3PRanch,
Right. But, I think the OP has the tank with only one gauge. 

"Tominco"@T3PRanch,
Right. But, I think the OP has the tank with only one gauge.

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Even if it has one gauge you do the same thing to see how full the pcp is. You just wont get the fill tanks remaining pressure. 

"Tominco"@T3PRanch,
Right. But, I think the OP has the tank with only one gauge.

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From OP 3rd post of the thread " I am using a Joe Guppy (with two gauges) as my main source of air."

Thurmond

Ahh... I missed that!
D'oh!

LDP, I know what you're saying, and you're absolutely right. That way works if the gauge shows the in-line pressure. I do that all the time with my system. 

The gauge on my fill adapter doesn't tell me how much air is in the gun. It only tells me how much pressure is in the fill adapter during filling. 


For example, if the the gun is at 100bar when I start, I open the tank valve and the pressure gauge shoots up to 3000 psi, then the gauge on the gun starts going up but the two gauges won't be the same until it's close to full and the pressure equalizes. The gauge on the fill adapter will read 3000 or 3500 psi all the way from 100 bar to 200-220 bar. It would read 4000 psi + if I open the valve all the way.

I haven't tried shutting off the valve before it's done filling but I'm not sure it would give me an accurate view of what's in the gun. If the gun was already full, it could easily over fill it. 

A number of the older air guns had no guage. I remember using an Evanix pistol like that. I think they expected people to use them with pumps or 3000psi tanks. I wouldn't risk a 4500psi tank with a gun with no guage and no regulator. If you were using a 3000 psi tank, it would be easy, you would just fill until it stopped filling. 

TOM ,is right all my Pcp airguns make a click sound whenfilling past the air level in the gun ...if your tanks gauge is accurate then just stop right after hearing the click .

Even if you went by the click sound a second you could just bleed out a little air .

One other thing is I have a Joe b line hooked to my omega and with his lines they are slow filling so you would really have to screw up to over fill .

"zebra"The gauge on my fill adapter doesn't tell me how much air is in the gun. It only tells me how much pressure is in the fill adapter during filling. 


For example, if the the gun is at 100bar when I start, I open the tank valve and the pressure gauge shoots up to 3000 psi, then the gauge on the gun starts going up but the two gauges won't be the same until it's close to full and the pressure equalizes. The gauge on the fill adapter will read 3000 or 3500 psi all the way from 100 bar to 200-220 bar. It would read 4000 psi + if I open the valve all the way.

I haven't tried shutting off the valve before it's done filling but I'm not sure it would give me an accurate view of what's in the gun. If the gun was already full, it could easily over fill it. 

A number of the older air guns had no guage. I remember using an Evanix pistol like that. I think they expected people to use them with pumps or 3000psi tanks. I wouldn't risk a 4500psi tank with a gun with no guage and no regulator. If you were using a 3000 psi tank, it would be easy, you would just fill until it stopped filling.

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That doesnt make sense to me. As soon as the check valve on your pcp opens the pressure between the pcp and the fill station will equalize. All of the pcp rifles I have owned work that way. I use a joe b slow fill and a luxfer 106 tank that fills fast but they both equalize pressure with the pcp when the check valve opens. I dont even use the gauge on my pcp rifles when filling I only use the gauge on my fill stations. Its very easy to fill my rifles with the fast flow and slow flow setups with out worry of over filling. I can take one of my rifles that is full and attach my fill station, open the valve without filling the rifle with more pressure. Once the fill stations gauge hits the desired pressure you simply close the valve. Even with a full pcp you just watch the gauge and close the valve as soon as it hits the desired pressure. Its quite easy.