HGRS Thermal Gas Mass Flow Meter

Thermal gas mass flow meter is a kind of gas flow measurement instrument based on the principle of thermal diffusivity, no need of temperature and pressure compensation. This type flow meter has wider range ratio.

Product Description

Technical Data


  • Structure type: Insertion type/ pipeline type; Compact type / remote type
  • Process connection: Flange or thread
  • Measurable flow velocity: 0.5 ~ 140 Nm/s @ 20 ℃, 101.33KPa
  • Measuring medium: clean gas fluid (without dust and dewing)
  • Ambient temperature: -20 ℃ ~ +70 ℃
  • Fluid temperature: -20 ℃ ~ +120 ℃, -20 ℃ ~ +350 ℃
  • Working Pressure: less than 4.2MPa
  • Accuracy: ± 1.5% F.S.
  • Repeatability: ± 0.2% of Calibration scale
  • Output: 4-20mA (load capacity > 600Ω) corresponding to instantaneous flow ( HART optional )
  • Communication interface: RS232, RS485 (optional)
  • Response rate: less than 1S
  • Supply voltage: 24VDC ± 10%, Electrical connection: M20 × 1.5
  • Probe insertion length: base on factory calculation
  • Probe diameter: 19mm (standard), Sensor diameter: 3mm (standard)
  • Protection tube material: SS304 (Please specify for other material)
  • Field Display: LCD, 4 digits for instant flow, 8 digits for total flow
  • Weather-proof: IP65, Ex-proof grade: Exd IICT6
  • Transmitter housing: powder coating on cast aluminum
  • Housing coating color: red for output 4-20mA or RS485, green for output 4-20mA+HART
Installation Requirement

1)  The instrument should be installed away from the elbow, obstructions, reducers, valves, in order to

ensure a steady flow field. Requirement to upstream straight pipe length and downstream straight pipe length as the following diagram shown( D is pipeline diameter):

straight pipe length

If the site conditions cannot meet requirements for straight pipe section, gas rectifier should be

cascaded to significantly reduce requirements to straight pipe section.


2)  When installing the flow meter, the short RTD sensor (RTD1) should face the direction of airflow, see the following diagram:

install direction


3)  Thermal mass gas flow sensor is actually a gas flow velocity sensor. Gas flows in pipeline, flow velocity of each point in the pipeline is different, generally the flow velocity at pipe’s wall is very slow but very fast at pipe’s center. So flow velocity at the detected point should be the average velocity throughout the pipe, the accuracy of average flow velocity point is directly related to accuracy of measurement. In order to get an optimal insertion length to make measurement more accurate, please supply detailed process condition before ordering.




Answer : Please send your question or enquiry to our email: sales@hginstrument.com, we will forward the questions to the related engineer.

Answer :  Please communicate with the sales about the return procedure before returning product.

Answer :  The delivery time depends on the order quantity and product specification.  If the product’s specification is conventional ( not special ),  delivery time is 5 or 7 working days for order quantity ≤ 10 pieces;  delivery time is 2 or 3 working weeks for order quantity 15 ~ 30 pieces. 

Answer :  by Courier,  by Sea or by Air

Answer :  Yes,  Generally warranty is one year.

Answer :  From year 2015  to year 2021,  average annual sales is RMB 350 million ( about USD 54.7 million )

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