HGRS Thermal Mass Flow Meter

HGRS Thermal 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.
Thermal Mass Flow Meter is a highly efficient and accurate flow measurement device that utilizes the principle of thermal dispersion to measure the flow rate of gases and liquids. It offers excellent stability and repeatability, making it ideal for applications in various industries such as oil and gas, chemical, and power generation. With its compact design and advanced digital technology, the Thermal Mass Flow Meter provides real-time flow data with high precision, making it a reliable and cost-effective solution for monitoring and controlling flow processes.

Product Description

Technical Data of  HGRS Thermal Mass Flow Meter


  • 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 for HGRS Thermal Mass Flow Meter

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 requirment to HGRS Thermal Mass Flow meter

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 for HGRS Thermal Gas Mass Flow Meter, the short RTD sensor (RTD1) should face the direction of airflow, see the following diagram:

install direction of HGRS Thermal Mass Flow meter

3)  HGRS Thermal Mass Flow Meter’s 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.


Main display interface of HGRS Thermal Mass Flow Meter

display of hgrs thermal gas mass flow meter

When the instrument is powered on, it will automatically do self-test, if self-test is ok, screen will display “Thermal Mass Flow meter” , then appears the main display interface as follow:


1:  “AL1” means channel1 alarming, “AL2” means channel2 alarming, user can select one or two variables to set limit alarm, the variables that can be set to alarm are instant flow rate, flow velocity, temperature.

2:  When the measured value exceeds the set value range, this area will display “OV”, which is the identifier of variable value overflow.

3: When the total flow exceeds 10000000, this area will display ”1K”, which means the actual total flow equal to total flow display value multiply by 1000.

4: Communication status indication, the first 3 digit is instrument’s address code;

The fourth digit is check digit, 0: none parity, 1: odd parity, 2: even parity;

The fifth digit is baud rate code, 0: 1200 bps, 1: 2400 bps, 2: 4800 bps, 3: 9600 bps.

5: Instantaneous flow rate, maximum display is 9999999

6: Total flow, maximum display of integer area is 8 digits, decimal area is 4 digits.

7: The current flow velocity (unit: Nm/s)

8: This area display flow rate percentage or temperature ( it depends on the configuration of the instrument )


1. What is Thermal Mass Flow Meter?
The Thermal Mass Flow Meter is a meter that measures the flow of a gas or liquid by measuring the heat it transfers within a pipe.

2. What is the working principle of Thermal Mass Flow Meter?
The Thermal Mass Flow Meter works by measuring the heat absorbed by a fluid as it passes through a pipe to calculate flow. When the fluid passes through the pipe, heat will be transferred to the pipe wall. The Thermal Mass Flow Meter will measure the temperature change of the pipe wall and calculate the flow rate of the fluid based on the law of heat conduction.

3. What fluids is the Thermal Mass Flow Meter suitable for?
Thermal Mass Flow Meter is suitable for the measurement of non-corrosive fluids such as gases and liquids.

4. What is the difference between Thermal Mass Flow Meter and other flow meters?
Compared with other flow meters, the Thermal Mass Flow Meter has a wider measurement range, can measure both low and high flow, and can be suitable for many different fluids. In addition, the Thermal Mass Flow Meter has high accuracy and stability, and has automatic temperature and pressure compensation functions.

5. What are the advantages of Thermal Mass Flow Meter?
The Thermal Mass Flow Meter has the advantages of fast response, high accuracy, strong reliability, easy installation and maintenance, and is suitable for a variety of industrial and laboratory applications.

6. What parameters does Thermal Mass Flow Meter require for measurement?
The parameters that the Thermal Mass Flow Meter needs to measure include fluid temperature, pressure and density.

7. What is the measurement accuracy of Thermal Mass Flow Meter?
The measurement accuracy of Thermal Mass Flow Meter depends on the specific instrument model and measurement range used, and generally can reach an accuracy of about 1%.

8. How to choose a suitable Thermal Mass Flow Meter?
When choosing a suitable Thermal Mass Flow Meter, you need to consider factors such as flow range, fluid type, usage environment, accuracy requirements, and installation methods. You can consult relevant professionals for help based on specific needs.

9. What are the requirements for the installation location of Thermal Mass Flow Meter?
The installation location requirements of Thermal Mass Flow Meter usually include: installation on horizontal pipes, avoiding the entry of large pieces of fluid or particles, stable pipe diameter, and avoiding direct sunlight, etc.

10. How to maintain and maintain the Thermal Mass Flow Meter?
Care and maintenance of Thermal Mass Flow Meter requires regular calibration, checking whether the sensor and circuit are damaged, keeping it clean and free from external interference, etc. Please refer to the product manual for details.

Before ordering HGRS Thermal Mass Flow Meter, need to confirm the following process information:

  1. Pipline size: ?
  2. Fluid: ?
  3. Process temperature: ?
  4. Process pressure: ?
  5. Flow rate of standard condition: ?





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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