Technology Advancements In Flow Measurement- Thermal Mass Flow Meter

By Author: Manish Patel
Total Articles: 1
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The constant-temperature sensor design maintains a constant temperature differential between a heated sensor and a reference sensor; the amount of power required to maintain the differential is measured as an indication of the mass flow rate. Constant-temperature thermal mass flowmeter currently popular with features as below:
Active
High-frequency response
The low electronic noise level
Immunity from sensor burnout when airflow suddenly drops
High rangeability
Compatible with various RTD Pt-100 sensors, such as hot thin film, wire wound, etc.
Applicability to gas flows


Constant Power Anemometry

Constant power sensor design maintains constant power between two temperature sensors which will provide a flow rate proportional to the temperature of the gas flows. This design is less popular and very limited usage due to technical limitations as below:
Passive, No feedback mechanism for any correction
No zero flow stability
Slow temperature & velocity response
Limited temperature compensation

Thermal mass flow ...
... meter measurement technology is gaining respect in gas mass flow rate measurement in various applications ranging from very low flow rates to ultra-high flow rates accurately with the best turndown ratio, its versatility, ruggedness, no pressure drop, easy installation against some of the conventional technologies such as Orifice, Aerofoil, Pitot-tube, Turbine & Vortex, etc.

Thermal mass flow measurement is realized in different ways and flowmeter types for satisfying different industrial needs such as
Laboratory style (with By-pass principle) for analytical & research purposes for
Inline Industrial style for intermediate pipe sizes from 15mm to 150mm generally
Insertion style for larger pipe sizes, etc.


Today’s process industries demand measurement technologies that are fairly priced and will help in optimizing process efficiency for reducing environmental emissions. To meet such demand, the manufacturers are focusing on the research and development of thermal mass flow sensor technology and its solutions concerning application expectations against other technologies.

For harsh applications customized Insertion Thermal Mass Sensors are available. Process gases stack emissions are corrosive. Chemical industries have to follow emission norms and measure the flow for this. It is impossible to measure the flow with conventional technologies. This has many challenges in measurement such as material compatibility & cost of ownership.

Manufacturers like LEOMI offer the following solutions
HALAR® (ECTFE) coated for corrosive gases up to 100°C (max) and
PFA Coated for Hot flue gas & corrosive process gases up to 200°C (max)

These advancements are an alternative to costlier Hastelloy C276 Insertion thermal mass flow sensor made or other special metal grades if any.
Other mass flow sensor advancement includes solutions for hot application with corrosive fumes, unknown waste-gas and gas traces in large ducts with low-pressure gas mass flow measurement
For more information on Thermal Mass flow measurement, you may contact LEOMI.