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Measuring water level reliably

  1. Aug 4, 2007 #1

    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

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  2. jcsd
  3. Aug 4, 2007 #2


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