How FCI Thermal Dispersion Sensors work?

Thermal Dispersion technology uses the principal of measuring the heat loss, or cooling effect, of a fluid flowing across a heated cylinder.

A typical flow element configuration uses two RTDs, sheathed in thermowells, separated by a gap. Heat is applied internally to one RTD relative to the other, creating a differential temperature between the two. This differential temperature is greatest at no flow conditions and decreases as flow increases, cooling the heated RTD.

Changes in flow velocity or immersion of the flow element into a liquid directly affect the extent to which heat is dissipated and, in turn the magnitude of the- temperature differential between the RTDs.

This differential is electronically converted into an electrical signal that can be used to trip a relay in flow or interface switch applications.

Since the relationship between flow rate and cooling effect is directly related to mass in gas applications, Thermal Dispersion technology, combined with advanced signal linearizing circuitry, is used to provide accurate measurement of gas or air mass flow rates.

FCI mass flow meters feature Thermal Dispersion technology in which the relationship between flow rate and cooling effect directly relate to mass flow in gas applications and provide a highly repeatable and accurate measurement of gas or air mass flow rates.

The electronics features advanced microprocessor-based circuitry to enable simple reconfiguration of the signal outputs, display or alarm in the field by using a built-in key pad or handheld communication.

Can I safely use FCI thermal flow switches and meters in hazardous (explosive) gases?
FCIs Thermal Technology is safe to use in near all flammable and explosive liquids and gases, including Hydrogen. Both flowmeters and switches are ATEX rated EExd, please ask for relevant certificate.

RTD improvements - better performance and lower costs
Most modern Thermal type designs operate on a differential between RTD's. Equal Mass design was a critical breakthrough that widely broadened Thermal technology and made it desirable for wide ranging process applications. RTD sensors further improved with precision platinum wound low mass designs. Today "state of the art" RTD manufacturing techniques which feature lithography etched chip RTD's have virtually eliminated production tolerances between RTDs. The result is a much higher pedigree RTD ideal for matching and available at dramatically lower costs. That directly results in driving the thermal technology towards higher performance and lower costs.

Microprocessors Drive improvements
There have been equally important breakthroughs in signal processing and firmware. FCI improvements in calibration data collection and signal processing introduced step change performance improvements with advanced curve fit algorithms. FCI's double polynomial curve fit breakthroughs for error and uncertainty reduction has undergone nearly a magnitude of improvement in recent years. FCI now regularly offers calibrations at 0.5% of reading and below across 100:1 turndowns.

In order to truly bring the pedigree of Thermal type products into the high performance category manufacturers needed to combine product improvements with investment in calibration facilities.

While newer modeling and equivalency methodologies have become effective at producing reference gas calibrations with accuracies approaching 2-3% of reading, it remains clear, for the time being, that the highest pedigree of performance is made available through actual gas or actual liquid calibrations. FCI's NIST Traceable Calibration Lab maintains capabilities for actual fluid or gas calibrations. Utilizing automated data collection routines and high accuracy flow references; sonic nozzles, laser Doppler and Coriolis meters provides for calibrations that are consistently better than 0.5% of reading.

FCI Flow Meters
FCI Flow Switches