COOPER GHG122

Core Technical Specifications

1. Supported Gas Types: Combustible gas (0–100% LEL), H₂S (0–100ppm), CO (0–500ppm), CO₂/CH₄ greenhouse gas
2. Sensor Lifespan: Catalytic bead sensor 5 years; electrochemical toxic gas sensor 2–3 years
3. Power Supply: 12–30VDC 2-wire loop power; maximum power consumption 2.5W
4. Output Signals: Standard 4–20mA analog loop; optional HART digital communication protocol
5. Response Performance: T90 response time ≤15 seconds; detection repeatability ±2% full scale
6. Explosion Certification: ATEX II 1G Ex ia IIC T6, IECEx Zone 0 intrinsic safety; UL Class I Div 1 certified
7. Protection Grade: IP66/IP67 full enclosure dust and high-pressure water jet resistance
8. Environmental Range: Operating -40°C ~ +70°C; humidity 10–95% RH non-condensing
9. Physical Parameters: 150mm outer diameter cylindrical enclosure, height 120mm; weight 1.8kg

Function Features

• Built-in automatic sensor zero drift compensation algorithm to reduce monthly calibration frequency
• Local digital LCD display with backlight showing real-time gas concentration and fault code
• Self-diagnosis function for sensor failure, circuit open-circuit, over-range gas concentration
• Configurable two-stage alarm threshold (pre-alarm and critical trip alarm) with relay contact output
• Remote parameter calibration and zero adjustment via HART handheld communicator without unit disassembly
• Vibration-resistant internal sensor mounting bracket for offshore marine platform installation
• Corrosion-resistant enclosure suitable for salt-spray coastal and offshore industrial environments

Working Principle

1. Ambient gas penetrates the stainless steel flame arrestor filter into the internal sensing chamber
2. Catalytic bead sensor oxidizes combustible gas molecules to generate resistance change proportional to gas concentration; electrochemical sensor produces ion current for toxic gas detection
3. Internal signal conditioning circuit converts sensor micro-signal into linear 4–20mA analog output corresponding to gas concentration range
4. Onboard microcontroller continuously executes self-test to detect sensor aging, blockage, or circuit faults
5. When gas concentration exceeds preset threshold, trigger dry contact relay output to activate audible/visual alarm or shut down process equipment
6. HART digital bus transmits sensor health status, calibration records, and real-time concentration data to gas safety PLC system

Material & Structural Characteristics

• Main Explosion-Proof Housing: 316L stainless steel casting with polyester anti-corrosion coating, anti-salt spray
• Flame Arrestor: Multi-layer sintered stainless steel mesh to prevent internal combustion flame propagation outward
• Sensor Chamber: PTFE inert plastic to avoid chemical adsorption interference with gas measurement
• Terminal Junction Box: Separate isolated wiring cavity, fully sealed EPDM rubber cable gland for cable entry
• Display Window: Toughened borosilicate explosion-proof glass with anti-fog coating

Installation Requirements

1. Mount combustible gas detectors 30–50cm above ground level (heavy-than-air gases); toxic gas detectors at human breathing height (1.5m elevation)
2. Install near valve flanges, storage tank discharge ports, pump seals, and ventilation exhaust outlets where gas leakage concentrates
3. Secure unit via M4 stainless steel mounting bracket; tighten cable gland to full compression for IP67 sealing
4. Run 2-core shielded twisted pair cable from control room 4–20mA gas monitoring panel; maximum transmission distance 1000m
5. All wiring inside hazardous area must comply with intrinsic safety Ex ia circuit wiring standards

Usage Precautions

• Perform full gas calibration with certified standard calibration gas every 6 months; replace expired sensors immediately
• Avoid installation locations with direct continuous solvent spray or heavy oil mist contamination
• Prevent mechanical impact or dropping of the unit to avoid cracking explosion-proof stainless steel housing
• Do not disassemble explosion-proof enclosure under live power in hazardous classified zones
• Clean flame arrestor mesh filter monthly with compressed dry air to remove dust blockage slowing gas response