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Core Technical Characteristics of NDIR Infrared Methane Sensors
The Nexisense series adopts non-dispersive infrared (NDIR) principle, utilizing the strong absorption band of CH₄ molecules near 3.31 μm. Through dual-channel (measurement + reference) pyroelectric or thermopile detectors comparing light intensity changes, concentration calculation is achieved. Based on the Lambert-Beer law, the output has an exponential relationship with concentration, converted to a linear signal via internal linearization algorithms.
Key performance parameters:
Range: 0-5/10/50/100%vol (optional 0-100%LEL version)
Resolution: 0.01%vol (low range) / 0.1%vol (high range)
Response time (T90): ≤15 s
Power consumption: ultra-low<100 mW (milliwatt level)
Expected lifespan: >10 years (continuous operation)
Operating temperature: -20°C to +60°C, with built-in temperature compensation
Explosion-proof rating: Ex ia IIC T4 Ga (intrinsically safe)
Compared to catalytic combustion sensors, NDIR has no oxygen dependency, is resistant to H₂S/silane poisoning, is minimally affected by moisture, and has extremely low zero and span drift, making it suitable for long-term unattended fixed installations.
Main Application Scenarios and Engineering Project Practices
Nexisense infrared methane sensors have been validated in multiple high-risk industrial scenarios, primarily serving system integrators and OEM manufacturers.
Coal Mines and Underground Mine Gas Monitoring
Deployed in fixed monitoring substations at heading faces, mining faces, and ventilation roadways. Sensor output connects to mine ring networks, supporting Modbus RTU or frequency signals, integrated with KJ series coal mine monitoring systems to achieve real-time CH₄ concentration upload, over-limit interlocking (1%vol warning, 1.5%vol power cutoff) for ventilation/personnel withdrawal. Project cases show that after replacing catalytic elements in high-gas mines, false alarm rates dropped >70%, and maintenance cycles extended to over 12 months.
Urban Gas Pipeline and Pressure Regulating Station Monitoring
Installed in underground valve wells, pressure regulating boxes, or key pipeline nodes to monitor pipeline leaks or abnormal accumulation. 4-20 mA / RS485 output connects to SCADA systems, supporting remote diagnostics and data trend analysis, complying with gas engineering standards such as GB 50493. In actual deployments, sensor arrays combined with GIS positioning enable rapid leak tracing.
Petrochemical and Chemical Park Explosion-Proof Areas
Suitable for explosive environments such as refineries, natural gas processing plants, and LNG receiving stations. Explosion-proof enclosure versions are integrated into online monitors or multi-gas detection stations, linked with SIS safety instrumented systems. Thresholds are set with reference to GBZ 2.1 occupational exposure limits (TWA 1000 ppm) and lower explosive limit (5%vol). In projects, NDIR sensors maintain stable output in complex atmospheres containing hydrogen sulfide.
Portable and Inspection Equipment Integration
Standard 4-series package (Φ20 mm × 21.7 mm) facilitates embedding in handheld CH₄ detectors or drone-mounted modules, supporting UART digital output for fast-response inspections.
Selection Guide and System Integration Considerations
Selection reference points:
Range selection: coal mine/gas priority 0-5%vol or 0-100%LEL, chemical/biogas engineering optional 0-100%vol.
Output type: analog 4-20 mA (two/three-wire), digital UART/Modbus RTU, facilitating PLC/SCADA access.
Explosion-proof and protection: intrinsically safe Ex ia preferred for portable, flameproof Ex d for fixed high-risk areas.
Power consumption and supply: low-power versions support battery-powered wireless nodes.
Environmental factors: verify moisture resistance (built-in filter), dust resistance, and temperature compensation range.
Integration considerations:
Installation position avoids direct airflow impact and strong vibration; gas chamber opening faces downward to prevent liquid accumulation.
Signal transmission uses shielded cables; 4-20 mA loop load ≤500 Ω; RS485 bus recommends adding 120 Ω terminating resistors.
System commissioning requires multi-concentration point calibration (0%, 20%, 50%, 80%) to establish temperature compensation curves.
In multi-sensor network deployment, unify Modbus address planning to avoid conflicts; reference channel data can be used for self-diagnosis.
When integrating with controllers, add opto-isolation to prevent electromagnetic interference; over-limit logic combines multi-level alarms (warning, alarm, interlock).
OEM Customization and Bulk Supply Advantages
Nexisense provides flexible OEM/ODM services, including:
Custom range, filter band (optimized selectivity for accompanying hydrocarbons such as C₂H₆)
Extended interface protocols (HART, LoRa, NB-IoT) and form factor adaptation
Integrated pressure/temperature multi-parameter compensation, custom output protocols
Brand labeling, laser coding, and supply chain traceability
Bulk supply features stable capacity, delivering thousands to tens of thousands of units according to project schedule, with tiered pricing, priority stocking, and joint environmental reliability testing. Long-term partners can participate in next-generation low-power or multi-gas NDIR development.
Frequently Asked Questions (FAQ)
1.What are the main advantages of Nexisense NDIR methane sensors compared to catalytic combustion type?
No oxygen dependency, resistant to poisoning, unaffected by H₂S/siloxanes, longer lifespan (>10 years vs 2-3 years), suitable for long-term fixed monitoring.2.How to set CH₄ concentration alarm thresholds and interlock logic in high-gas mines?
Typical warning 0.8-1.0%vol, alarm 1.0-1.5%vol, power cutoff ≥1.5%vol, linked to ventilation fans and power disconnection.3.How effective is the sensor in suppressing moisture interference?
Built-in reference channel and filter design keeps moisture cross-interference <±0.1%vol (90% RH), superior to traditional single-channel NDIR.4.Which communication protocols are supported for integration into existing SCADA or mine ring networks?
Standard UART/Modbus RTU, some models support 4-20 mA + HART, customizable Profibus or EtherNet/IP.5.What is the standby current of low-power versions in wireless monitoring nodes?
<50 μA standby, suitable for lithium battery-powered LoRa/NB-IoT nodes, with continuous monitoring intervals up to several minutes.6.What is the minimum order quantity for OEM customization of specific range or anti-accompanying gas interference?
Standard modules start at 500 units; custom filter or algorithm projects typically start at 2000 units, development cycle 8-14 weeks.7.What is the response time and accuracy performance of the sensor at low temperatures of -20°C?
After built-in compensation, T90 extends to<20 s, accuracy maintained at ±3% FS, zero drift <±0.05%vol/year.8.How to implement sensor self-diagnosis and fault output?
When reference channel is abnormal, light source decays, or range is exceeded, output specific current (e.g., 3.5 mA) or Modbus status register.9.Does bulk procurement provide per-batch calibration certificates and consistency reports?
Yes, NIST-traceable multi-point calibration reports, batch statistics, and optional third-party explosion-proof verification support are provided.10.What is the recommended sensor placement density and maintenance cycle for gas pipeline projects?
Key nodes place 1 point every 50-200 m, maintenance cycle 12-18 months (zero/span verification), far exceeding catalytic type.
Conclusion
Nexisense is committed to providing reliable NDIR infrared methane detection solutions for industrial safety system integrators, coal mining equipment manufacturers, and gas engineering enterprises. If your company requires sensor selection, technical support, or custom development for fixed monitoring networks, portable inspection equipment, or OEM integration projects, welcome to contact us for in-depth discussion of specific requirements and collaboration paths. Together, let’s enhance combustible gas leak prevention and ensure production and personnel safety.
