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how full is the expansion tank?

how full is the expansion tank?

how full is the expansion tank?

We have a hydraulic skid with an expansion tank with a bladder inside.  It is plumbed into the piping near the pump inlet. The assembled system is carefully conditioned and bled.  The topside of the bladder get charged to a few psi with Nitrogen.  Thoughtful folks would like to be able to Confirm how full the system is from time to time.

Is there an inexpensive method of checking the approximate fluid level, or at least confirming it is above some minimum level? An electronic signal output would be nice for monitoring, but even a visual method would be better than nothing.

I've been thinking about a sight glass toward the bottom of the exp tank, but don't know if bladder diaphragms can survive rolling across a potentially sharp edged hole, plus the skid is already made. Maybe a level sensor in the plumbing near the bottom of the exp tank.


Dan Timberlake

RE: how full is the expansion tank?

How about a pressure transducer in the Gas section?

Bud Trinkel CFPE
fluidpower1 @ hotmail.com

RE: how full is the expansion tank?

Is there anywhere in the tank you could drill holes for a common tank wall sight gauge and thermometer?

Alternately, if any ports at bottom and top you could connect small hoses and run them off to a sight gauge mounted remotely. One hose to bottom of gauge, one to top for venting back to top of tank.

Or, Small nylon tubing that you could connect to top and bottom of tank, use that as a sight gauge.

Most sight gauges can easily take 5 psi.

We usually use the square bladders in tank as breathers, don't pressureize, but keeps atmospheric air from going in and out. Made in England, don't recall the name.

If anyone has more common US sources I'd appreciate names.


RE: how full is the expansion tank?

I am wondering that there is a method to calculate by a pressure gauge in the suction of the pump.(usually is fitted)
Considering that a precise gauge can give u the level.
1 ATM = 10330 mmH2O
So if u can find the specific gravity of the fluid i think you can achieve your scope....

RE: how full is the expansion tank?

If you know the volume of the tank you're charging with the nitrogen, and the pressure it was charged at, then the change in volume is inversely proportional to the change in pressure by the ideal gas law which is most likely sufficient at the temperature and pressure range you're working with.  The decrease in volume of the nitrogen is equal to the increase in bladder volume.

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