Guy's need your support,I want to measure closed tank level which is under

Guy's need your support,I want to measure closed tank level which is under vacuum -630mmHg using DP Transmitter, tank fluid density 1.38, Tank height is 7ft

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Guy's need your support,I want to measure closed tank level which is under vacuum -630mmHg usin..

Answer / r_vaya

In such case vaccume will apply in both lags equally .
Now hight is 7 ft and density 1.38

7 ft is equal to 84 inches

So ,
84 X 1.38 = 115.92 inches of H2O became our span.

1 inches of H2O = 1.87 mmHg

Thus,
115.92 inches H2O = 216mmHg

tank is closed thats why ,

LRV = - 216 mmHg
URV = 0 mmHg

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Guy's need your support,I want to measure closed tank level which is under vacuum -630mmHg usin..

Answer / sr

mothods of measurements don't change with change in line pressures ... the methods r same for both +ve and -ve pressure .... in vacuum u just have to take care that vacuum shud not break ....

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Guy's need your support,I want to measure closed tank level which is under vacuum -630mmHg usin..

Answer / carl_ellis

A differential pressure transmitter is required to correct for vacuum pressure. The DP's low side is installed high up, tapped into the vacuum and the DP's high side tapped in near the bottom.

The DP transmitter's minimum range (LRV) is zero

The DP transmitter's maximum range (URV) is:
maximum level height (inches or mm) * specific gravity

Liquid level = measured pressure in water column units (inches or mm) / specific gravity

Many digital indicators just scale the 4-20mA to the desired level range; so a calculation involving specific gravity isn't needed.

For example:
4.0 mA = 0.0 inches level
20.0 mA = 84.0 inches level

Carl Ellis
Measure First