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 wet leg & constant level application for density measurement. This is only used for constant level application.
Density Measurement using DP Transmitter

Density Measurement using DP Transmitter for closed tank with wet leg 
The minimum and maximum process specific gravities can be obtained from process datasheets.
The formulas for calculating the tranmitter LRV and URV are;
HP Side/LRV/4ma = L.Smin – H.Sref
LP Side/URV/20ma = L.Smax – H.Sref
Where
L = Closed tank maximum measured level
H = Height of wet leg
Smax = Maximum process specific gravity
Smin = Minimum process specific gravity
Sref = wet leg or reference leg specific gravity
Note: This calculation is only used for closed tank with wet leg and for constant level application.
4 comments
Need to learn Instrument .
yes you all right
Sir what is dry&wet leg???
I can’t understand about Dp transmitter function.. So kindly give the dp function & working….
dry leg and wet leg both are impuls line,
wet leg means impuls line used to other liquid so specific gravity is different to the tank liquid.
dry leg both are used same specific gravity that means tank and impuls line are same liqid.