DP - Pad Cell Transmitter with Liquid & Gas Phase calculator

As shown below, in a close tank level measurement installation, if a gas phase exists on top of the liquid, the gas pressure must be compensated

This is because a change in the gas pressure will cause a change in the level transmitter (output mA). Furthermore, the pressure exerted by the gas may be so high that the pressure due to the column of liquid becomes insignificant. A pressurized close tank application requires a reference connection. A reference connection is a connection from the transmitter (LT) low side to the top of the tank. Its purpose is to compensate and balance out the pressure above the liquid so that a true level measurement can be made. If there were no reference or compensating connection, the transmitter would indicate the level plus the tank pressure