High-performance LLQ GAS Roots Flowmeter Dual Rotors and Positive Displacement System

The LLQ series Roots Flowmeter suitable for non corrosive gases such as natural gas, city gas, propane, butane, air, nitrogen, and industrial inert gases.

It is mainly used for gas commercial settlement in industries such as catering and hotels, gas metering in transmission and distribution pipelines, gas pressure regulating stations, industrial and civilian boilers, and can also be used as a standard flow meter.

This product complies with JB/T7385-2015<Gas Roots Flowmeter>and JJG633-2005<Gas volumetric flowmeter calibration regulations.

Flowmeter structure:

Working principle:

This flowmeter is a positive displacement flowmeter, and the measuring chamber consists of two rotors with a waist wheel shape in cross-section that mesh and rotate. As gas flows through the measuring chamber, the pressure difference force generated between the inlet and outlet of the measuring chamber drives the two waist wheel rotors connected to a pair of high-precision synchronous gears to rotate, completing the rotation process from A-B-C-D. The gas in the measuring chamber formed by the enclosed space between the inner wall and cover plate of the measuring chamber and the pair of waist wheel rotors periodically enters and exits the chamber;  The rotational speed of the waist wheel rotor is proportional to the flow rate of the measured gas passing through the flowmeter. The rotational speed value is transmitted through a dedicated sensor to the integrator for shaping and filtering, and then converted into a standard voltage pulse signal output. The frequency of the pulse signal is proportional to the common volume flow rate of the fluid inside the pipeline.

The built-in high-precision pressure and temperature sensors simultaneously measure the temperature and pressure of the fluid and transmit signals into an integrated intelligent integrator. The integrator converts the signals of flow rate, temperature, and pressure and accurately calculates and integrates them to accurately measure the standard volume flow rate and mass flow rate of the gas.

Main technical parameters:

Flow meter specifications, basic parameters, and performance indicators (see Table 1)

Table 1

Signal Transmission for Gas Flow Meters

Accurate and Stable Remote Signal Output for Gas Measurement

Gas flow meters require high-stability signal transmission due to low density, pressure fluctuations, and safety requirements.

• 4–20 mA Output: Ensures stable transmission for natural gas, compressed air, and industrial gases, even in electrically noisy environments.

• Pulse Output: Commonly used for gas consumption calculation and billing systems.

• RS485 / Modbus Communication: Enables digital remote reading and integration into gas monitoring networks and control rooms.

• Explosion-Proof Signal Output (Optional): Designed for hazardous areas such as gas pipelines, chemical plants, and energy facilities.

Key Benefits:

• Accurate remote gas flow monitoring

• Safe data transmission in industrial environments

• Reduced on-site inspection frequency

Automation Capability of Gas Flow Meters

Reliable Gas Flow Control for Industrial Automation

Gas flow meters are essential components in automated gas supply and safety systems.

Supports integration with PLC, SCADA, and DCS systems

Enables automatic gas flow regulation through control valves

Suitable for burner control, compressed air systems, and process gas distribution

Provides real-time feedback for safety interlocks and alarms

Automation Benefits:

• Improved gas usage efficiency

• Enhanced operational safety

• Faster system response to flow changes

IoT & Smart Monitoring for Gas Flow Meters

IoT-Enabled Gas Flow Monitoring for Smart Energy Management

With IoT connectivity, gas flow meters become part of intelligent energy and safety management systems.

Wireless Communication Options: NB-IoT, LTE-M, LoRa, or Ethernet for remote locations and wide-area monitoring

Cloud-Based Gas Monitoring: Real-time gas flow data uploaded to cloud platforms for centralized supervision.

Alarm & Event Management: Automatic alerts for abnormal flow, leakage risks, or pressure fluctuations.

Data Analytics & Energy Optimization: Helps identify gas consumption trends and optimize energy usage.

IoT Advantages:

• Remote gas consumption management

• Early leak detection and risk reduction

• Support for smart energy and industrial IoT systems

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