Processing Magazine

Liquid Level Displacer Transmitter

October 9, 2012

The Magnetrol Digital E3 Modulevel Liquid Level Displacer Transmitter, an intrinsically safe two-wire instrument used for continuous liquid level measurement, liquid/liquid interface level measurement or density control, utilizes a high-temperature, custom design of the Macro Sensors PR Series of separate core LVDT Linear Position Sensors as part of the internal electronics needed to convert liquid level changes into 4-20mA output signals.The Magnetrol Digital E3 Modulevel Liquid Level Displacer Transmitter, an intrinsically safe two-wire instrument used for continuous liquid level measurement, liquid/liquid interface level measurement or density control, utilizes a high-temperature, custom design of the Macro Sensors PR Series of separate core LVDT Linear Position Sensors as part of the internal electronics needed to convert liquid level changes into 4-20mA output signals. The Liquid Level Displacer Transmitters are used in the chemical industry, petroleum refining, nuclear, power generation and oil field industries for various level applications. The Magnetrol Digital E3 Modulevel Liquid Level Displacer Transmitter implements simple buoyancy principles to detect and convert liquid level changes to useable measurement output. Changing buoyancy forces caused by a liquid level change act upon the spring-supported displacer of the transmitter, causing a vertical motion of the core within the Macro Sensors AC-operated LVDT Linear Position Sensor installed near the top of the transmitter. As the core position changes with liquid level, voltages are induced across the secondary windings of the separate core LVDT. These signals are processed in the electronic circuitry of the LVDT Linear Position Sensor and used to control the current in the 4-20 mA output. An enclosing tube acts as a static isolation barrier between the LVDT and the process media. As the link between the level sensing element and output electronics is simple in mechanical design and construction, the transmitter maintains an inline design that results in low instrument weight and simplified installation.