In open tank applications, the level can be measured with either gauge or differential pressure (DP) transmitters, using the assumption that P = LS. If specific gravity needs to be measured, then the equation can be modified to S = L/P. For this to work, the level must stay constant so that any pressure changes reflect the specific gravity change. This works well in a tank where there is no change in level, such as when it is desirable to measure a density change as a way of monitoring a reaction, or as the fluid’s temperature changes.This calculation tool only used for constant level application.
Density Measurement for Open Tank
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| Density Measurement using DP transmitter for open tank for constant level application |
The formulas for calculating the tranmitter LRV and URV are;
HP Side/LRV/4ma = LSmin
LP Side/URV/20ma = LSmax
Where
L = Open tank maximum measured level
Smax = Maximum process specific gravity
Smin = Minimum process specific gravity
Note: This calculation is only used for open tank vented and for constant level application.