The principle of pressure transmitters, when used to determine fluid levels, is as follows: the pressureat the bottom of a fluid body is proportional to theheight of the fluid above it. This is the hydrostatic head pressure, and is measured by the transmitterto obtain the fluid level reading.

Measurement of level in industrial application by differential pressure transmitteris frequent. The DP Transmitter device is used to measure level as an inferentialmeasurement. In a DP Transmitter, the diaphragm senses the head pressuredeveloped by the height of the material in the vessel.

Continuous level sensors measure level within a specified range and determine the exact amount of substance in a certain place, while point-levelsensors only indicate whether the substance is above or below the sensing point. Generally the latter detect levels that are excessively high or low.

It offers a very high accuracy over a wide temperature range, an excellent repeatability and very long term stability. Large numbers of transmitters can be interconnected in a multi-drop configuration to help cut down on cabling.

The sensor is isolated from the process by a stainless steel diaphragm and a filling liquid. The electronics are located within the hermetically sealed transmitter housing which gives the Series 500 an excellent resistance to shock and vibration.