Accurate level measurement, variable fluid density

The Foxboro Measurements and Instruments Division of Invensys Process Systems has introduced a level transmitter that delivers accurate measurement in either open or closed tanks.

The Foxboro Measurements and Instruments Division of Invensys Process Systems has introduced a level transmitter - a new IMV31 density-compensated level transmitter available with Hart Communications - that delivers accurate measurement in either open or closed tanks.

Based on hydrostatic measurement and advanced multivariable sensing technology, the IMV31 Density-Compensated Level Transmitter uses differential pressure, pressure, and temperature measurements to compensate for liquid and vapor density changes.

It transmits a 4 to 20 mA output signal proportional to level and provides Hart digital communications.

"Users like the simplicity, reliability, and low cost of DP transmitters for tank level applications.

However, until now, they had no easy, cost-effective way to compensate the output for fluid density changes that would otherwise cause errors in the level measurement.

We solved that problem by adding on-board level calculations to our multivariable transmitter.

Our IMV31 continuously calculates density based on measurements of pressure and temperature, and uses this information along with its differential pressure measurement to calculate tank level," said Ken Brown, vice president and general manager of Foxboro Measurements and Instruments.

The IMV31 is suitable for both open (vented) and closed (pressurised) tanks and compensates for density changes in the tank liquid and vapour and density changes in both vapour and liquid in external dry or wet legs.

This makes the transmitter ideally suited for critical applications such as boiler drum level and for other high performance applications where fluid densities are significantly affected by variations in pressure and temperature.

By consolidating multiple measurements in a single device, the IMV31 minimises the number of transmitters required, which enhances reliability while reducing wiring, installation, and inventory costs.

The IMV31 density-compensated level transmitter is available for immediate shipping.

A configurator software package for Foxboro multivariable transmitters, Model PCMV, has been enhanced to Version 3.0 to allow easy setup and commissioning of the IMV31 transmitter.

The configurator includes an extensive fluid properties table and also allows user-entry of custom liquid parameters.

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