Fixed HC gas detectors utilize the catalytic combustion detection principle, to accurately measure the concentration of Hydrocarbon gases in the air. These gas sniffers are essential for safety, as they provide early warnings of gas leaks, helping to prevent potentially hazardous situations like explosions or fires.
Features
- Hydrocarbons gas detector adopts high precision sensor for accurate gas leak detection.
- Hydrocarbons gas detector is equipped with 3-wire system 4-20mA analog output, relay output, RS485 output (optional).
- The HC gas monitor is compatible with various controlled alarms, PLC, DCS and other control system, and can be remote monitored.
- Explosion-proof design, fast, relaible and stable.
- Infrared ray controller can remote control the alarm point settings, zero calibration, and address modification.
- Two-stage alarm with sound and light, and the alarm point is settable.
- The Hydrocarbons gas detector has self-calibration function, and three standard keys will be used to realize on-site maintenance.
- The HC gas detector can output one or two on-off signals, and can drive a ventilator, solenoid valve or other external devices.
Specification
| Model |
GD300-HC |
| Detection Principle |
Catalytic Combustion |
| Gas |
Hydrocarbons (HC) |
| Range (Optional) |
0-100% LEL |
| Resolution |
1% LEL |
| Calibration Kit |
Gas pressure regulator (calibration gas cylinder NOT included) |
| Accuracy |
≤±3% F.S. |
| Response Time |
≤10s |
| Repeatability |
≤±1% |
| Recovery Time |
≤10s |
| Linearity Error |
≤±1% |
| Zero Shift |
≤±1% (F.S./year) |
| Signal Output (Optional) |
4-20mA and RS485 Relay output: one group of relay output (1NO+1NC, 5A/30V) for one alarm (default), or two groups of relay output (2NO+2NC, 5A/30V) for high/low alarm (optional). |
| Alarms |
Sound, light |
| Display |
High light nixie tube display |
| Installation |
Wall-mounted, piping type, flow-type (according to the detected environment) |
| Connection |
Power connection type: G1/2 male thread explosion-proof flexible pipe Pipe-mounted type: M45*P2.0 |
| Operating Time |
24h |
| Explosion-proof Grade |
II 2G Ex db IIC T4 Gb |
| Protection Grade |
IP65 |
| Certification |
CE, ATEX (Standard: EN IEC 60079-0:2018, EN 60079-1:2014) |
| Working Voltage |
12-36V DC |
| Case Material |
Die-casting aluminum housing |
| Operating Temperature |
-20℃~50℃ |
| Operating Humidity |
0~95%RH (non-condensing) |
| Dimension |
206*179*90mm |
| Weight |
≤1.6kg |
| Power Adapter |
Input 100-240VAC 50/60Hz, Output 24VDC 1A (Optional USA plug, Europe plug, AU plug or UK plug) |
| Accessories (Optional) |
Calibration kit - gas pressure regulator (calibration gas cylinder NOT included)
- Body Material: Brass
- Max. Input Pressure: ≤15MPa
- Max. Output Pressure: 0.25MPa
- Flowmeter Range: 0.1-1.5 L/min
- Mounting Connection: Inlet port: W21.8-14; Outlet port: Ф6 flexible tube
|
Notes
Regarding the flow rate for gas detectors, there are 2 types:
- Pump-Suction Type: Equipped with a built-in pump, with a flow rate of 600 mL/min. (Models: GD200, GD400, GD600)
- Diffusion Type: Not equipped with a built-in pump, with a flow rate of 300 mL/min. (Models: GD300, GD500, GD800)
If you require a customized flow rate, please let us know your specific requirements. We will evaluate whether customization is possible. A flow rate that is too high or too low can affect measurement accuracy, so we recommend using an appropriate flow rate for your application.
Flow rate only needs to be considered when sampling gas from pipelines. For measuring gas concentrations in normal ambient air, you do not need to consider the flow rate. To measure confined spaces such as pipelines, please get in touch with us and provide the detailed conditions of use.
Dimensions (Unit: mm)

Installation Guide
The following precautions apply when connecting the GD300 series fixed gas detector to a pipeline:
- Working pressure should be stable at 1 bar ±10%, and the flow rate should be controlled at 300 mL/min.
- Working temperature is -20°C to +50°C.
- Working humidity is 0–95% RH. When the humidity is above 60% RH, it is recommended to use a dehumidifier or add a filter. When the humidity is above 95% RH, the gas is essentially saturated with water, making measurement impossible.
- The gas detector should be installed indoors. If it is installed outdoors, a rain cover should be added to protect the entire instrument.
- For the second pipeline connection method of the GD300 gas detector, the pipe-mounted installation, the detector mounting thread size is M45 × P2.0. During installation, hold the detector with both hands, keeping the sensor parallel to the mounting thread. Align it with the threaded port, rotate the detector clockwise, and install it in the desired position. To prevent gas leakage at the threaded connection, an appropriate amount of thread seal tape can be wrapped around the sensor head thread before installation.
***Other Common Gases and Ranges Available for Fixed Gas Detectors
Note: Some common gases and the measuring ranges are listed in the above table. For more information, please feel free to contact us.
Details

Tips: What is a fixed Hydrocarbons (HC) gas detector?
A fixed Hydrocarbons (HC) gas detector is a stationary device used to continuously monitor and detect the presence of Hydrocarbon gases in industrial environments, such as oil refineries, chemical plants, and offshore drilling platforms. These detectors are designed to provide early warning of gas leaks, ensuring safety and preventing hazardous situations like explosions or fires. They operate using various sensing technologies, including infrared, catalytic bead, or semiconductor sensors, to accurately measure hydrocarbon gas concentrations. Once a dangerous level is detected, the system triggers alarms and can initiate automatic shutdown procedures. Fixed HC gas monitors are crucial for maintaining workplace safety, and regulatory compliance, and protecting both personnel and equipment from potential gas-related incidents. Regular maintenance and calibration of these detectors are essential to ensure their accuracy and reliability in detecting gas leaks.