Nexisense Thermal Gas Mass Flow Meter | Inline/Insertion Thermal Diffusion Mass Flow Meter RS485 Modbus Gas Flow Sensor

Focus Section

Solving the challenges of precision gas mass flow measurement and system integration, providing direct, uncompensated, high-reliability gas metering solutions

Nexisense thermal gas mass flow meters utilize the constant temperature differential thermal diffusion principle to directly measure gas mass flow. They are suitable for common steady-state gases (except unstable media such as acetylene and boron trichloride), with pipe diameters ranging from DN6 to 2000mm, flow velocities from 0.1 to 100Nm/s, and accuracy of ±1~2.5%. They are widely used in gas metering scenarios requiring high precision and no temperature/pressure compensation.

Three Core Selling Points:

• Direct Mass Flow Measurement and Wide Range: Based on the constant temperature differential principle, no temperature and pressure compensation is required. It offers a wide measurement range (flow velocity as low as 0.1Nm/s) and good repeatability, suitable for gases from micro-flow to large-flow.

• High Stability and Anti-interference Capability: The sensor has no moving parts, features a simple and robust structure, and excellent anti-vibration performance. The digital circuit design provides strong anti-interference and low long-term drift.

• Easy IoT Integration Capability: Supports 4-20mA (opto-isolated) and RS485 (Modbus RTU, opto-isolated) outputs. On-site LCD display (instantaneous mass flow, standard volume flow, cumulative flow, etc.) facilitates connection to DCS, PLC, and SCADA systems for remote parameter setting and data traceability.

Overview

The Nexisense thermal gas mass flow meter is a new generation of gas mass flow measurement instrument based on the thermal diffusion principle. The core of the instrument uses two reference-grade platinum resistance temperature sensors: one acts as a temperature sensor to continuously measure the medium temperature T1, and the other acts as a velocity sensor that self-heats to a temperature T2 higher than the medium temperature. By maintaining a constant ΔT (T2-T1), as gas flows through, the airflow carries away heat causing T2 to drop. The instrument maintains the constant temperature differential by increasing heating power, which is a fixed functional relationship with the gas mass flow rate, thereby achieving direct and accurate mass flow measurement.

The product has the advantages of small volume, high degree of digitalization, easy installation, and accurate measurement. The structural forms include inline (integrated or split) and support for insertion and full-pipe installation. Pipe materials are compatible with carbon steel, stainless steel, plastic, etc. The on-site display uses a four-line Chinese character LCD, which can simultaneously display mass flow, standard volume flow, cumulative flow, standard time, standard flow velocity, and other parameters.

Nexisense strengthens industrial IoT features on the basis of classic thermal flow meters. System integrators can easily connect to existing automation platforms via the standard RS485/Modbus RTU protocol, supporting free parameter setting, remote diagnosis, and data uploading; engineering contractors can quickly deploy in projects in industries such as petrochemicals, metallurgy, power, environmental protection, and biopharmaceuticals, ensuring the stability, reliability, and traceability of the gas metering process.

The instrument truly achieves mass flow measurement without the need for temperature and pressure compensation for gas flow. It features fast response speed (1s), low pressure loss, and easy maintenance, making it a preferred device for industrial gas flow measurement.

Main Advantages

Nexisense thermal gas mass flow meters have been optimized in sensor design, signal processing, and system integration, highlighting stability, high precision, anti-interference capability, and easy integration to meet the strict requirements of B2B projects for gas metering.

1. Constant Temperature Differential Thermal Diffusion Principle and Direct Mass Measurement: Using the constant temperature differential method, the sensor consists of two platinum resistors—one measuring the medium temperature and the other heating while maintaining a constant temperature difference. The heat carried away by gas flow is directly related to the mass flow, requiring no temperature or pressure compensation, and offering accurate measurement with good repeatability. Even if gas composition or environmental conditions change, the output remains highly stable.

2. Wide Range and High Adaptability:

• Pipe diameter range: DN6 ~ 2000mm, covering from small pipes to large pipes.

• Flow velocity range: 0.1 ~ 100Nm/s (extendable to 120Nm/s), wide range ratio, suitable for various gas velocities, including low-velocity leak detection scenarios.

• Working pressure: Medium ≤ 1.6MPa (insertion type), higher pressure can be customized; temperature range: sensor -40~+300℃, converter -20~+45℃.

• Suitable for common steady-state gases, with good measurement performance for many different gas velocities.

3. Industrial-grade Structure and Anti-interference Protection:

• No moving parts, simple and robust structure, low pressure loss, good anti-vibration performance, long service life, and low failure rate.

• Digital circuit design, overall digital measurement, convenient maintenance.

• Output signals use opto-isolation (4-20mA max load 500Ω, RS485), providing strong anti-interference capability.

• Protection level IP65, suitable for harsh industrial site environments.

• Sensor material in stainless steel or carbon steel, strong corrosion resistance.

4. Convenient Operation and Easy Integration:

• Parameters can be freely set, operation is convenient, supports on-site LCD display and remote configuration.

• Supports 1-2 channels of normally open alarm contact outputs.

• RS485/Modbus RTU (or HART optional) communication enables factory automation and integration. Data includes instantaneous flow, cumulative flow, status, etc., facilitating inclusion in industrial IoT platforms.

• Flexible installation methods: Insertion type suitable for large pipe diameters, inline type suitable for small and medium pipe diameters. Simple installation and maintenance, supports bidirectional detection.

These technical advantages make the Nexisense thermal gas mass flow meter more than just a traditional flow instrument; it is a reliable node that can be deeply integrated into the gas metering and control systems of smart factories, helping users reduce compensation errors and improve process control accuracy.

Technical Specifications

Main technical parameters of Nexisense thermal gas mass flow meter:

Performance and Features:

• Direct mass flow output without temperature and pressure compensation

• Good anti-vibration performance, no moving parts, low pressure loss, stable performance

• Wide measurement range, high sensitivity, good repeatability

• Digital design, strong anti-interference capability, parameters can be remotely transmitted

• Supports factory automation integration

Application

Nexisense thermal gas mass flow meters are widely used in industrial scenarios requiring precision gas mass flow metering:

1. Petrochemicals and Natural Gas Processing: Measuring process gas flows such as air, nitrogen, oxygen, and natural gas. Supports RS485 connection to DCS for precise production process control and energy metering.

2. Flue Gas and Combustion Air Monitoring in Power Industry: Monitoring boiler combustion air or flue gas flows. The non-compensation feature ensures stable measurement. Data integration into SCADA systems aids energy saving and emission reduction.

3. Environmental Protection and Waste Gas Treatment Engineering: Measuring biogas, landfill gas, industrial waste gas, etc. The wide range ratio is suitable for variable operating conditions. Works with Modbus for remote emission monitoring and alarms.

4. Metallurgy and Gas Transmission Systems: Precisely metering blast furnace gas, shielding gases, etc. Supports large-diameter insertion installation, reducing installation costs and pressure loss impact.

5. Gas Proportioning in Pharmaceutical and Food Industries: Controlling clean gas flows such as nitrogen and compressed air to ensure gas metering accuracy and batch traceability in production processes.

6. Laboratory and Gas Leak Detection: Utilizing low-velocity high-sensitivity characteristics for gas leak detection or standard device calibration, supporting remote parameter settings.

Wiring and Installation

Installation and wiring tips (please refer to the product manual for details):

• Choose appropriate installation method: Inline recommended for small pipe diameters, insertion recommended for large pipe diameters; ensure the sensor probe is located at the pipe center or recommended position to avoid turbulence interference.

• Medium inside the pipe should be clean steady-state gas; clean impurities before installation. The arrow direction must align with gas flow; supports bidirectional detection.

• Electrical Wiring:

• Power: Correctly connect DC 24V positive and negative poles, power not less than 18W.

• 4-20mA Output: Use shielded cable for signal lines, opto-isolated.

• RS485: Correctly connect A/B signal lines, suggest terminal resistor configuration (usually 120Ω), supports multi-slave networking.

• Alarm Contacts: Connect external alarm circuits as needed.

• Perform parameter settings after power-on (on-site or remote), slowly vent gas to observe display and output stability.

• Regularly check sensor surface cleanliness; maintenance is simple and frequent calibration is not required.

Installation environment should avoid strong electromagnetic interference sources; place the converter in a suitable temperature location.

FAQ

Q1. What is the fundamental difference between Nexisense thermal gas mass flow meters and volume flow meters?
Thermal mass flow meters directly measure mass flow without temperature and pressure compensation; volume flow meters require extra compensation to calculate mass flow. Thermal types are more accurate and convenient.

Q2. What is the minimum flow velocity and pipe diameter range? Is it suitable for micro-flow?
The minimum flow velocity is 0.1 Nm/s, and pipe diameters cover DN6~2000mm. With a wide range ratio, it is suitable for gas measurement from micro-flow to large-flow, including leak detection applications.

Q3. What output methods are supported? Can it be integrated into PLC or SCADA?
It supports 4-20mA and RS485/Modbus RTU (opto-isolated), allowing easy connection to DCS, PLC, or industrial IoT platforms for remote monitoring and parameter setting.

Q4. What are the requirements for the measurement medium? Can unstable gases be measured?
It is suitable for common steady-state gases. Unstable or corrosive media like Acetylene and Boron Trichloride cannot be measured. The medium should be free of large amounts of impurities.

Q5. What is the working pressure and temperature range?
Medium pressure is generally ≤1.6 MPa (higher can be customized). Sensor temperature is -40~+300℃, and converter temperature is -20~+45℃.

Q6. Is installation and maintenance convenient? Are there moving parts?
The structure is simple with no moving parts, resulting in low pressure loss. Insertion and inline installations are flexible, maintenance is simple, and anti-vibration performance is good.

Q7. How is the accuracy? Is regular compensation or calibration required?
Accuracy is ±1~2.5% with good repeatability. The digital design has low drift, and the calibration cycle is relatively long, depending on specific operating conditions.

Q8. Does it support HART or other communication protocols?
Standard configuration is RS485/Modbus, with HART as an option. Please confirm communication requirements during selection.

Summary

Nexisense thermal gas mass flow meters, centered on the constant temperature differential thermal diffusion principle, provide professional and reliable gas metering solutions for system integrators and engineering contractors thanks to direct mass flow measurement, wide range, high stability, anti-interference capability, and easy RS485/Modbus integration. It effectively solves the compensation challenges and integration pain points of traditional flow meters, ensuring the accuracy, real-time nature, and traceability of gas flow data.

Whether in petrochemical process control or environmental engineering emission monitoring, the Nexisense thermal gas mass flow meter will become the stable foundation of your gas measurement system.

Need guidance on pipe diameter selection, medium compatibility confirmation, Modbus register mapping table, or a custom project quote?
Welcome to contact the Nexisense technical team. We will provide professional selection suggestions and complete technical support based on your gas type, pipe diameter, flow range, pressure/temperature conditions, and system integration needs. Act now to make gas mass flow measurement more direct, smarter, and more efficient.