Introduction to COOPER GHG122
Product Description
The COOPER GHG122 is a rugged industrial gas detector designed for continuous monitoring of combustible and toxic gases in hazardous environments. Manufactured by Cooper Safety, a division of Cooper Industries specializing in safety instrumentation, this device is engineered to provide early warning of gas leaks, ensuring worker safety and preventing potential explosions or health hazards in industries such as oil and gas, chemical processing, mining, and wastewater treatment.
Featuring a compact, weatherproof design and advanced sensor technology, the GHG122 can detect a wide range of gases including methane, propane, hydrogen sulfide (H₂S), and carbon monoxide (CO). Its robust construction—including a 316L stainless steel housing and high-impact polymer components—allows it to withstand extreme temperatures, vibration, and exposure to corrosive substances. The detector integrates both visual and audible alarms, along with analog and digital outputs, enabling seamless integration into safety systems and control rooms for real-time hazard management.
Technical Parameters
- Detectable Gases: Combustible gases (methane, propane, etc.) and toxic gases (H₂S, CO, etc.)—configurable based on sensor type
- Measurement Range:
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- Combustible gases: 0-100% LEL (Lower Explosive Limit)
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- H₂S: 0-100 ppm; CO: 0-500 ppm (adjustable based on toxic gas type)
- Accuracy: ±5% of reading (for combustible gases); ±3 ppm or ±5% of reading (whichever is greater) for toxic gases
- Response Time: T90 ≤ 30 seconds (combustible gases); T90 ≤ 60 seconds (toxic gases)
- Output Signals: 4-20 mA analog output; 2 relay outputs (SPDT, 5A/250V AC) for alarm/control
- Communication: Optional HART protocol for remote configuration and diagnostics
- Power Supply: 12-30 V DC (typical 24 V DC), power consumption ≤ 2.5 W
- Operating Temperature: -40°C to +70°C (-40°F to +158°F)
- Relative Humidity: 10-95% RH (non-condensing)
- Enclosure Material: 316L stainless steel with polyester coating
- Protection Rating: IP66/IP67 (dust-tight and water-resistant)
- Certifications: ATEX/IECEx (Zone 0/1/2 for gas), UL/cUL Class I Div 1, FM approved
- Sensor Life: 2-5 years (depending on gas type and operating conditions)
- Dimensions: 150mm (diameter) × 120mm (height); weight: 1.8 kg
Usage Methods
- Installation:
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- Mount the detector in a location where gas leaks are most likely (e.g., near valves, storage tanks, or ventilation outlets), ensuring unobstructed gas flow to the sensor.
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- Position combustible gas detectors at or slightly above floor level (since most combustible gases are heavier than air); mount toxic gas detectors based on gas density (e.g., H₂S detectors at breathing height).
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- Secure the detector using M4 mounting brackets, ensuring a tight seal to prevent vibration-induced damage. For hazardous areas, use explosion-proof conduit fittings.
- Wiring:
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- Connect the power supply (12-30 V DC) to the terminal block, ensuring correct polarity.
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- Wire the 4-20 mA output to a safety PLC, DCS, or gas monitoring panel for continuous data logging.
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- Connect relay outputs to alarm devices (sirens, beacons) or control systems (ventilation fans, shutoff valves) to automate safety responses.
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- For HART communication, connect a twisted-pair shielded cable to the dedicated terminals, grounding the shield at the control system end.
- Configuration:
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- Power on the detector and allow 30 minutes for sensor stabilization.
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- Use a compatible HART communicator or configuration software to set gas type, alarm thresholds (e.g., low alarm at 20% LEL, high alarm at 50% LEL), and relay logic.
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- Perform a zero calibration using clean air (or nitrogen for toxic gas sensors) to establish a baseline reading.
- Operation and Maintenance:
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- Monitor the 4-20 mA output and alarm status via the control system; verify visual indicators (LEDs) show normal operation (green = healthy, red = alarm).
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- Test the detector monthly using a calibration gas mixture (e.g., 50% LEL methane) to ensure accurate response.
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- Replace the sensor every 2-5 years (per manufacturer guidelines) or if drift exceeds ±10% of calibration values.
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- Clean the sensor housing quarterly with a soft brush to remove dust or debris; avoid using solvents that may damage the sensor.
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- Recalibrate the detector annually using certified calibration gases and a precision regulator.
System Introduction
The COOPER GHG122 functions as a critical component in industrial gas safety systems, integrating with three key layers:
- Detection Layer: The gas sensor (catalytic bead for combustibles, electrochemical for toxic gases) reacts with target gases, generating a current proportional to gas concentration.
- Processing Layer: Internal electronics convert the sensor signal into a 4-20 mA output (0 mA = 0% of range, 20 mA = full scale) and trigger relays when alarm thresholds are exceeded.
- Safety Response Layer: The control system uses detector data to activate alarms, notify personnel, and initiate mitigation actions (e.g., shutting down equipment, activating ventilation) to prevent exposure or ignition.
In a typical refinery application, the GHG122 monitors for propane leaks near a storage tank. If propane levels reach 20% LEL (low alarm), the detector triggers a local beacon and sends a 8 mA signal to the control room. At 50% LEL (high alarm), it activates a shutdown relay to close the tank valve and starts ventilation fans, while the 12 mA output alerts operators to evacuate the area.
Related Models in the Series
- GHG122-EX: Explosion-proof variant with enhanced housing (IP68) for Zone 0 applications, suitable for offshore platforms or chemical reactors.
- GHG124: Dual-sensor model, combining combustible and toxic gas detection (e.g., methane + H₂S) in a single unit, ideal for multi-hazard environments.
- GHG122-W: Wireless version with LoRa or 4G connectivity, eliminating wiring costs in remote locations (e.g., pipeline right-of-ways, remote wellheads).
- GHG130: Compact detector with reduced power consumption (≤1.5 W), designed for battery-powered systems or solar installations.
- GHG150: High-precision toxic gas detector with ppm-level resolution, optimized for ultra-sensitive applications (e.g., laboratory gas monitoring).
- GHG-CON: Central controller compatible with up to 32 GHG122 detectors, providing centralized monitoring, alarming, and data logging for large facilities.
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