Thermal Mass Flow Meter

Parameter	Specification
Accuracy	2% Reading
Repeatability	0.5%
Turndown Ratio	Up to 100:1
Response Time	≤ 1 second
Operating Pressure	Up to 40 bar (customizable)
Operating Temperature	-20°C to +250°C
Ambient Temperature	10°C to +60°C

Key Features

Direct Mass Flow Measurement

Measures gas mass flow directly without the need for external pressure and temperature compensation.

High Accuracy & Repeatability

Ensures precise and stable measurement even at low flow rates.

Wide Turndown Ratio

Capable of measuring a broad range of flow rates (up to 100:1).

No Moving Parts

Provides long service life with minimal wear and virtually no maintenance.

Low Pressure Drop

Non-intrusive design minimizes impact on system pressure.

Fast Response Time

Quick detection of flow changes for better process control.

Multi-Gas Capability

Suitable for gases such as air, nitrogen, oxygen, biogas, and natural gas.

Robust Construction

Built with high-quality SS 316 / SS 316L materials for harsh industrial environments.

Flexible Installation

Available in insertion and inline types for different pipe sizes.

Multiple Output Options

Supports 4–20 mA, pulse output, and RS485 (Modbus RTU) communication.

User-Friendly Display

Clear LCD/LED display for real-time flow rate and totalized flow.

Energy Monitoring & Leak Detection

Ideal for compressed air systems to improve energy efficiency.

Working Principle

The working principle of a thermal mass flow meter is based on the concept of convective heat transfer. The flow meter consists of a heated element (often referred to as a sensor or probe) and temperature sensors. These sensors are usually located upstream and downstream of the heater. The heater continuously maintains a constant temperature difference (ΔT) relative to the fluid. As the fluid flows past the heated element, it absorbs heat due to convective heat transfer. The temperature sensors measure the temperature difference (ΔT) between the heated element and the fluid. This temperature difference is directly proportional to the rate at which heat is carried away by the fluid, which in turn correlates with the mass flow rate of the fluid. By knowing the heat input (power supplied to the heater) and monitoring the temperature difference (ΔT), the mass flow rate of the fluid can be calculated using specific calibration factors and the physical properties of the fluid (such as thermal conductivity and specific heat).The flow meter processes this data to provide an output signal that directly indicates the mass flow rate of the fluid.

Industrial Applications

Thermal Mass Flow Meters are widely used across industries for accurate measurement and control of gas flow. Their direct mass flow measurement capability, without requiring temperature or pressure compensation, makes them ideal for various industrial processes.

Oil & Gas Industry

Natural gas flow measurement in pipelines
Flare gas monitoring and control
Gas distribution and custody transfer (non-fiscal)
Fuel gas flow measurement in burners and heaters

Chemical & Petrochemical Plants

Process gas flow monitoring
Reactor feed gas control
Inert gas flow measurement (Nitrogen, Argon)
Gas blending and batching systems

Power Plants

Combustion air flow measurement
Boiler fuel gas monitoring
Primary and secondary air measurement
Stack emission monitoring

Steel & Metallurgy Industry

Blast furnace gas measurement
Coke oven gas flow monitoring
Oxygen and nitrogen supply control
Compressed air distribution

Pharmaceuticals & Biotechnology

Clean gas flow measurement (O₂, N₂, CO₂)
Fermentation air control
Process gas monitoring in sterile environments
Utility gas measurement

Food & Beverage Industry

CO₂ flow measurement in carbonation
Nitrogen flushing and packaging
Compressed air monitoring
Utility gas management

Cement Industry

Kiln combustion air measurement
Preheater and calciner gas monitoring
Bag filter and dust collector airflow
Compressed air system monitoring

Water & Wastewater Treatment

Aeration air flow measurement
Digester gas monitoring (biogas)
Blower air flow control
Methane gas measurement

Semiconductor & Electronics Industry

High-purity gas flow measurement
Process gas control in fabrication
Cleanroom gas monitoring
Specialty gas applications

General Industrial Utilities

Compressed air consumption monitoring
Leak detection systems
HVAC air flow measurement
Energy management systems

Technical Specifications

Parameters	Details
Measuring Medium	Gas (Except Acetylene & Steam)
Velocity	0.1 – 100 Nm/s
Accuracy	±2.5% / ±1.5% Reading (Insertion) ±1% Reading (Flange)
Response Time	1 second
Output	4–20 mA (optoelectronic isolation, max load 500Ω), Pulse, RS485 (Modbus), HART
Power Supply	Compact: 24VDC or 220VAC (Power Consumption ≤18W) Remote Type: 220VAC (Power Consumption ≤19W)
Working Pressure	Insertion Type ≤1.6 MPa Flange Type ≤4.0 MPa Tri-Clamp ≤1.6 MPa Thread ≤4.0 MPa
Ambient Temperature	-20℃ ~ 50℃
Medium Temperature	-20℃ ~ 150℃ (Customizable up to 400℃ in remote version)
Transmitter Housing	Die-cast Aluminium
Cable Entry	M20×1.5 Standard, 1/2" NPT Optional
Ingress Protection	IP65 / Explosion Proof
Display	4 Digit LCD – Mass Flow, Volume Flow, Flow Totalizer
Flow Units	Nm³/h, Nm³/min, kg/h, kg/min and more
Alarm Output	2 Relays, 3A / 250VAC, 3A / 30VDC
Structure Type	Remote or Integral
Cable Length (Remote)	Standard 10 meters
Pipe Material	Carbon Steel, Stainless Steel, Plastic
Insertion Type	Size: DN32 – DN4000 mm Rod, Valve, Sensor Material: SS304 / SS316L / SS316
Flange Type	Size: DN10 – DN300 (Can be designed above DN300) Flange Standard: ANSI, DIN Tube Material: SS304 / SS316L / SS316 Sensor Material: SS304 / SS316L / SS316 Flange Material: SS304 / SS316L / SS316
Tri-Clamp Type	Size: DN10 – DN100 Tube Material: SS304 / SS316 Sensor Material: SS316
Thread Type	Size: DN10 – DN100 Tube Material: SS304 / SS316L / SS316 Sensor Material: SS304 / SS316L / SS316

Flow & Velocity Table

Size (DN)	Min Velocity (Nm/s)	Max Velocity (Nm/s)	Min Flow (Nm³/h)	Max Flow (Nm³/h)
10	0.1	100	0.028	28.27
15	0.1	100	0.063	63.61
20	0.1	100	0.113	113.09
25	0.1	100	0.176	176.71
32	0.1	100	0.289	289.52
40	0.1	100	0.452	452.38
50	0.1	100	0.706	706.85
65	0.1	100	1.194	1194.59
80	0.1	100	1.809	1809.55
100	0.1	100	2.827	2827.43
125	0.1	100	4.417	4417.86
150	0.1	100	6.361	6361.72
200	0.1	100	11.309	11309.73
250	0.1	100	17.671	17671.45
300	0.1	100	25.446	25446.90
350	0.1	100	34.636	34636.05
400	0.1	100	45.238	45238.93
450	0.1	100	57.255	57255.52
500	0.1	100	70.685	70685.83
600	0.1	100	101.787	101787.60
700	0.1	100	138.544	138544.23
800	0.1	100	180.955	180955.73
900	0.1	100	229.022	229022.10
1000	0.1	100	282.743	282743.33

Model Selection Table

Parameter	Options
Model	SS FLOW_TMFM_LINE
Size	Specify Pipe Size
MOC	1 – SS304 2 – SS316 3 – Other
Protection	1 – IP65 2 – IP67
Pressure	1 – Up to 16 Bar 2 – Other
Explosion Proof	1 – Yes 2 – No
Connection	1 – Flange 2 – Thread 3 – Clamp 4 – Insertion
Output	1 – 4–20 mA 2 – RS485 3 – 4–20 mA + Pulse 4 – 4–20 mA + HART 5 – 4–20 mA + RS485 6 – 4–20 mA + Pulse + RS485
Temperature	1 – 80°C 2 – 150°C 3 – 250°C 4 – Above 250°C
Relay	1 – Switching 2 – With Additional Output 3 – NA
Power Supply	1 – 24V DC 2 – 230V DC
Test Certificate	1 – Factory Calibration 2 – NABL Lab

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