Thermal Mass Flow Meter- Technology Advancement

Thermal mass flow 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 purpose for, Inline Industrial style for intermediate pipe sizes from 15mm to 150mm generally & Insertion style for larger pipe sizes, etc.

Due to continuous development, thermal mass flow technology is evolving removing some of the challenges. Mainly there are two design working principles:

• Constant Temperature Anemometry

• Constant Power Anemometry

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

Whereas the 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

LEOMI aiming Optimizing Life of industrial process, equipment & machine has identified this promising technology benefits and developed product solutions with more than 20 years of experience. Leomi utilizes Constant Temperature Anemometry combined with digital precise over-temperature control for producing Insertion thermal mass flow meter with German technology engineered in India.

Today’s process industries demand measurement technologies with fairly priced & which will help in optimizing process efficiency for reducing environmental emissions. To meet such demand, the LEOMI team is focusing on the research and development of thermal mass flow sensor technology and its solutions concerning application expectations against other technologies. In pursuit of this LEOMI has developed customized Insertion Thermal Mass Sensor for mass flow rate measurement:  

• HALAR® (ECTFE) coated for corrosive gases up to 100°C (max)

• PFA Coated for Hot flue gas & corrosive process gases up to 200°C (max)

considering corrosive process gases stack emission. Many chemical industries have to follow emission norm with has many challenges in measurement such as material compatibility & cost of ownership. This innovative sensor probe works much better where conventional flow technology is impractical.  

LEOMI’s other mass flow sensor advancement is considering a hot application with corrosive fumes, unknown waste-gas and gas traces in large duct with low-pressure gas mass flow measurement 

Above advancements by Leomi is an alternative to costlier Hastelloy C276 Insertion thermal mass flow sensor made or other special metal grades if any.

LEOMI’s technical team is continuously working on research of other alternatives for various gas mass flow measurement solutions keeping in mind different industries’ process conditions.

Request to kindly do write us your application and challenges to us which enable us to guide in the development of suitable sensor if not in the existing product range.