Compact Thermal Flow Meter for Gases

Compact thermal flow meters are specifically designed for the measurement and process control of various small-flow gases. This series of sensors utilizes advanced microelectromechanical systems (MEMS) flow sensing chips and is suitable for various clean gases. They are low-cost, easy to install, require no temperature or pressure compensation, and can replace traditional volumetric or differential pressure flow meters.

RFQ Thermal Gas Mass Flow Meters

Features

Utilizes a microelectromechanical system (MEMS) flow sensing chip.
The sensor exhibits strong resistance to interference.
The sensor maintains stable zero-point performance.
High accuracy and excellent repeatability across the measurement range.
Standard mechanical interface for easy installation.
RS485 communication output with standard MODBUS RTU protocol.
Features an LCD display for instantaneous and cumulative flow readings, providing clear, intuitive, and convenient readings.
Standard 4-20mA current signal output and one PNP output (customizable PNP pulse output or 0-5V/0-10V output).
Display orientation (0°, 90°, 180°, 270°) is selectable.

Technical Parameters

Operating power supply	DC24V/2.5W	Accuracy (%)	±(1.5FS)
Medium temperature	-10~50℃	Humidity	<95%RH (No frost, no ice)
Operating pressure	≤1.0MPa (pressure customizable), integrated pressure measurement and display available upon request.	Display	Instantaneous flow, cumulative flow
Output method	4-20mA	Communication Method	RS485 (Modbus RTU protocol)
Mechanical connection	BSPT and G internal threads are available; see mechanical interface connection dimensions for details.	Response Time (ms)	50-1000

Note:
The above data was measured at 25°C, 101.32 kPa, and dry air conditions.
Minimum measurable flow rate: 0.3 NL/min.
Maximum measurable flow rate: 3000 NL/min.
Customizable with temperature and pressure measurement capabilities.

Flow Range

Maximum measurable flow rate
DN8	DN10	DN15	DN20	DN25	DN32
100L/MIN	300L/MIN	500L/MIN	1000L/MIN	2000L/MIN	3000L/Min

If you require other flows, please contact us for customization.

Mechanical interface connection dimensions
DN8	DN10	DN15	DN20	DN25	DN32
G1/4 female thread BSPT 1/4 female thread	G3/8 female thread BSPT 3/8 female thread	G1/2 female thread BSPT 1/2 female thread	G3/4 female thread BSPT 3/4 female thread	G1 female thread BSPT1 female thread	G1-1/4 female thread BSPT 1-1/4″

Standard connectors can be used for interface conversion as needed.

Compact Thermal Flow Meter Measurement Principle

A compact thermal flow meter contains two temperature sensors placed within the medium. One sensor is heated to a temperature above ambient temperature, while the other senses the medium’s temperature.

As the flow rate increases, the medium carries away more heat. The temperature difference between the two sensors changes with the flow rate. The flow rate Q can be calculated from the proportional relationship between the temperature difference and the flow rate.

Currently, most compact thermal flow meters are used to measure gases; only a small number are used to measure minute liquid flow rates.

Featured Application

The Compact Thermal Flow Meter is suitable for mass flow monitoring of dry, clean, and non-corrosive gases such as air, nitrogen, argon, carbon dioxide, and oxygen. It has been widely used in university research, fire protection, environmental monitoring, tobacco, smart agriculture, food, and pharmaceutical industries.

Default measurable gases include: air, oxygen, nitrogen, argon, carbon dioxide, hydrogen, helium, methane, and propane. Other gases can be customized according to your requirements.

Compact Thermal Flow Meter Customized for High Temperatures up to 200°C

Common gas settings are as follows. The gas type can be switched by adjusting the conversion coefficient.

Item	Gas	Internal conversion coefficients	Range percentage
1	Air	1	1
2	Oxygen O2	0.9861	0.9861
3	Nitrogen N2	0.994	0.994
4	Argon	1.4066	1.4066
5	Nitric oxide NO	0.9702	0.9702
6	Nitrogen dioxide NO2	0.7366	0.7366
7	Carbon dioxide CO2	0.7326	0.7326
8	Methane CH4	0.7147	0.7147
9	Ethane C2H6	0.4781	0.4781
10	Propane C3H8	0.3459	0.3459

More Gas Flow Meters and Controllers

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**DC-M500 Digital Gas Mass Flow Controller/Flow Meter**

DC-M100 Digital Flow Controller-Flow Meter — **DC-M100 Digital Flow Controller/Flow Meter**

AC-S030 Micro-range Mass Flow Controller-Flowmeter — **AC-S030 Micro-range Mass Flow Controller/Flowmeter**

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