water tank question

**chopped** · 11-03-2012, 06:24 PM

I have a submersable well with a standard blue water/air storage tank.Its approximatly
30 years old now,Id have to say its performed well.After getting air in my lines , I dug and replaced the pitless , and it seemed that the air was gone for awile but returned, ( ihave another posting about this).Someone suggested that I not have a check valve near the tank, so I removed the one that the original instller had there, turns out it was bad anyways..
So the question to pnder now is this.with the tank check valve removed All the system water was drained and pressure in tank as eliminated.
I took a few minutes to prepare the piping to reattach without the check valve and when I bent down I could hear an ever slight hiss noise.(air).I figured maybe the tank was leaking air from the bladder, so I place my thumb over the pipe and the noise went away , leading to think it was coming out the tank and manifold.This was asteady his leak, much like a tire or air hose would make.
I see the tire gauge on the valve and I had 28 lbs.( thats 2 pounds below switch kick in.)The tank has seemed to maintain the 28 lbs for several weeks since I checked it. I went ahead and put the piping back on and awile later small air bubbles came in the outlet stream.
Now, My thougth is maybe the tank has a slight leak. But its hard to believe that it cold leak so Id hear it hiss for all these weeks now.(5 at least) and not show a drastic decrease in the tank pressure.But it must be coming from somehwere..I took the 28 lb readign with the tank completly empty.Also wondering if its possible that it would only leak air when its in a certain position .like at the lowest pressure before pump comes on , maybe the rubber leaks a bit then and not through the rest of the cycle.
Any ideas are sure welcome please.
driving me nuts.
simply , I can think the tank is at fault as its age, but hard to believe it coudl leak that much and not change the pressure of air.
Thanks all for your time to read all this..

**valveman** · 11-04-2012, 05:42 AM

When you hook the tank up to water, the water has as much pressure as the air in the tank. So the water is trying to get in the bladder while the air is trying to get out. In other words the air can't leak out to atmosphere when the water pressure is pussing back on it. But the air will slowly leak into the water and the tank will become waterlogged.

**LLigetfa** · 11-04-2012, 06:31 AM

Originally Posted by valveman

When you hook the tank up to water, the water has as much pressure as the air in the tank...

+1

In other words, they are in near equilibrium. The loss of air in operation is much more gradual.

**chopped** · 11-07-2012, 06:30 AM

I guess My real question was, If for example you got a new tank that was precharged or you filled it with air.
And NO water present. Shoudl there be any type of a hiss coming out the inlet for the water. Thats what mine does. So Im not sure if it has a small leak or not. but it seems to hole the charge of air with no troubles.So im letting it go for awile and see .