Measuring water level reliably

[Micko]

Hello,

Can you help me understand physical meaning of measuring water level by measuring differential pressure.
In open water tank it's fairly easy. One side of the transmitter is open and exposed to athmospheric pressure. In such case, differential pressure is directly proportional to water level: deltap = density * g * level, and simply I can setup appropriate scale for instrument.

In case if tank is closed under high pressure and temperature, level is measured with differential transmitter as shown on right picture. Tankage is made of steam and water, in upper part is steam and in lower part is condensated water. Of course, there are inlets and outlets, but I didn't draw them for simplicity. This drawing I have found in one article which I didn't understand well, because of lack of detailed informations. One transmitter pipe (steam side) has some kind of vessel whose purpose is to condensate steam int water, so practically both pipes to transmitter is filled with water.
Now, I wonder how to place pipes on the tank to measure water level correctly? In other words, on which spots one must drains the holes?
Also, I know that because of high pressure and temperature, level that would be calculated as in previous way is not correct, so there must be involved compensation by pressure and temperature (because water density is changed). Do you know where to find steam and water tables for such purpose?

Thanks in advance

 

[Gokul43201]

http://imrl.usu.edu/thermo/green/frames/a7f.htm

 

[ravenprp]

for your help.

Hi there,

Measuring water level using differential pressure is a common and reliable method. The physical meaning behind this method is that the pressure exerted by the water is directly proportional to its depth. This means that the deeper the water, the higher the pressure will be.

In an open water tank, the pressure on one side of the transmitter is atmospheric pressure, while the other side is exposed to the pressure exerted by the water. This creates a difference in pressure, which can be measured and used to determine the water level.

For closed tanks under high pressure and temperature, the method is a bit more complex. As you mentioned, one side of the transmitter is filled with water, while the other side has a vessel that condenses the steam into water. In this case, it is important to place the pipes in the correct spots in order to get an accurate measurement. Generally, the pipes should be placed near the top and bottom of the tank, as this will give the most accurate readings.

In terms of compensating for pressure and temperature, there are tables that can be used to calculate the correct level measurement. These tables can typically be found in engineering handbooks or online resources. It is important to use the correct values for pressure and temperature in order to get an accurate measurement.

I hope this helps to clarify the physical meaning behind measuring water level using differential pressure. Let me know if you have any other questions. Thank you.