In closed tanks, the DP transmitter must compensate for the pressure of the vessel above the liquid surface. So the LP side of transmitter is connected to the tank. Here in this post we are discussing about calibration of DP transmitter for a closed tank with dry leg & constant level application for density measurement. This calculation tool only used for constant level application.
Closed tank Density Measurement

Density Measurement using DP Transmitter for closed tank with dry leg 
The formulas for calculating the tranmitter LRV and URV are;
HP Side/LRV/4ma = LSmin
LP Side/URV/20ma = LSmax
Where
L = Closed tank maximum measured level
Smax = Maximum process specific gravity
Smin = Minimum process specific gravity
Note: This calculation is only used for closed tank with dry leg and for constant level application.