how much air pressure


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Old 04-14-06, 05:20 AM
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how much air pressure

should there be in a blader type water tank..The tank is in a pump house with a 1/2 hp shallow well pump supplying the water. The house belonged to my deceased brother, and we are fixing it up a little...I don't know what size in gallons it is, but i did get the dimensions of the tank..16" high X 15" diameter..It is a blue tank, and on the side i can read Aqua- Air Water Tank, and the name "A O Smith". I can not find anything pertaining to how much the pressure should be.. I checked the pressure with the pump unplugged and and drained and its only about 5 lbs...I do not want to just start putting air in without gettig advice because i don't want to break the bladder....Also one more question,,Does the pump need to be completely level to work properly...Right now the pump is sitting on a stack of 8" cinder blocks about the hieght of the tank, and turned at about a 25 degree angle with the motor end pointing down, and the plastic pump housing pointing up...Thanks for all replies...
 
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Old 04-14-06, 10:42 AM
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Set it to 2 psi less than the CUT-IN pressure of the water pump.
That's the pressure at which the well water pump turns on minus 2 psi.

Usually this is 22 psi lower than the pressure when fully pumped up.
So this can give you somewhere to start.
If you have a working gauge on the water system this also helps a lot.


> I checked the pressure with the pump unplugged and and drained and its only about 5 lbs...

Way too low.

There is an empirical way to set the pressure without any gauges. It takes some trial an error and wastes a lot of water, but it puts the pressure exactly where in should be.

When the pressure is too low, the full capacity of the tank is not used and the pump runs on a very short cycle which means very frequent starts and stops - and that is bad for the pump.


With the pump unplugged, open the tank drain wide open.
After the click of the relay for the pump, the water should keeps running only another 2 seconds.

If it runs longer, the pressure in the water pressure tank is too low.
If it runs out an instant before the click, the pressure is too high.

Then with the pump plugged in and fully pumped up, drain the tank wide open.
When the tank is almost empty, the pump will turn on.
If the water stops flowing for a brief moment, the pressure in the tank is too high.
The flow should be continuous (although it might be slower).
Close the valve and let the pump fill the tank.


> Does the pump need to be completely level to work properly...

No.

> at about a 25 degree angle with the motor end pointing down

Air could get trapped in there under certain circumstances which makes priming the pump much harder.
So in this case, you should try to bring the motor up.


I'm sorry to hear that you lost your brother.
 

Last edited by bolide; 04-14-06 at 11:06 AM.
  #3  
Old 04-14-06, 04:22 PM
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thanks Bolide for being so informative to my question and appreciate the comment about my Brother, I can sense you are a caring individual....thanks again, Oren
 
 

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