Dayton pressure tank issue

[tropics surfer]

not quite 5 year old 3GVT9 62 gal. tank with partial use (muni. water 50% of the time). Water press. low, checked and instead of 30 psi (32-52 range) it showed 25. So, tried to add more air and for some reason, neither of two air pressure gauges would register.
Put new valves in Schrader fitting, still no reading.
No visible water leak. Ran the air (tire) compressor for about 2 minutes to the tank and no reading on the air pressure gauge, but when I opened the nearest tap, water came out under pressure, for about a minute. Which seems to tell me the tank is holding air.
And no change in the water pressure (bladder) gauge--it will not move and stays at about 10 psi.
I could put in a new water pressure gauge, but without knowing what amount of air pressure is in the pressure tank, I' m still lost.

 

[Valveman]

Use your car tire pressure gauge to check the air in the tank. The pressure gauge on the line should read the same as the tire pressure gauge on the tank as long as there is water pressure in the tank. But turn the pump off, open a faucet, drain all the water from the tank, the line gauge should read zero and your car tire gauge should read 30 PSI on the tank.

 

[Sponsor]

 

[Reach4]

car tire gauge should read 30 PSI on the tank.

tropics surfer has a long earlier thread where he described his system as using the big pressure tank as a water reserve for when the city water turns off. So an unusual setup.

 

[tropics surfer]

valveman, I did just that, pump off, tank is drained completely, line gauge reads zero. But when I put the air compressor to the pressure tank, it appears to be taking pressure. but my 2 tire pressure gauges will not read any air going into the tank. And the line gauge stays flat.
No visible water (bladder) leaks and no sound of an air leak. But as I said, my test yesterday showed it is pushing water out after a two minute air compression. Flummoxed!
There is 2 months left on the tank warranty, for whatever that's worth..

 

[Valveman]

If the bladder is bad, air will just keep coming out the faucet when running the air compressor. But if you close all the faucets the air pressure should build up even if the bladder is bad.

 

[Reach4]

And the line gauge stays flat.
No visible water (bladder) leaks and no sound of an air leak. But as I said, my test yesterday showed it is pushing water out after a two minute air compression. Flummoxed!

How many cfm is your compressor. A tiny compressor can take a really long time to raise the pressure 1 psi.

 

[tropics surfer]

Not sure about the compressor- it is a Craftsman 250 psi, small but works. Will make another attempt tomorrow.
Appreciate the help, thanks.

 

[Reach4]

Not sure about the compressor- it is a Craftsman 250 psi, small but works. Will make another attempt tomorrow.
Appreciate the help, thanks.

"250 PSI" cigarette lighter plug compressors are usually not good. They can take a while to pump up a bicycle tire, a long time to pump up a car tire, and a lot more time for a pressure tank.. A real compressor will have a SCFM or CFM specification at a specified pressure.

 

[tropics surfer]

absolutely right and today I will leave it on longer until it works or blows up. I don't have a regular compressor so we shall see. Thanks, I think you've pinpointed it.

 

[tropics surfer]

Reach, thanks again..I ran the compressor for 2 intervals to allow it to cool for about 25 minutes total and the pressure now reads 18 psi.
Tomorrow I'll get it up to 28-30psi.
In the past I'd never needed to add more than 3-4 lbs. of air so didn't know what I was up against starting at zero.