Understanding Fixed Gas Detector Layout in Explosion Zones
In hazardous environments classified as explosion zones, the layout of fixed gas detectors is critical to ensuring early detection of combustible and toxic gases. Proper spacing, positioning, and sensor selection directly impact response time, coverage area, and system reliability. This article outlines the technical rules and best practices for arranging fixed gas detectors in Zone 1 and Zone 2 areas, focusing on spacing standards, sensor technology selection, and system integration.
Spacing Rules Based on Gas Behavior and Environmental Conditions
Spacing between detectors is not arbitrary. It is determined by the physical properties of the target gas, ventilation patterns, and equipment layout. For flammable gases, detectors should be placed no more than 5 meters apart in still air environments, reducing to 3 meters in high-risk zones with frequent gas release points. In areas with forced ventilation, spacing can extend to 7 meters only if airflow direction is known and consistent.
Vertical placement matters: lighter-than-air gases (e.g., methane) require detectors near the ceiling, while heavier-than-air gases (e.g., propane, gasoline vapor) should be detected at floor level or within 30 cm of the ground. For mixed or unknown gas types, a multi-level detection approach is recommended using detectors at both upper and lower levels.
Selecting the Right Detection Principle for Your Application
The performance of a gas detection system depends heavily on the detection principle used. At Shanghai Gewe Electronics Safety Equipment Co., Ltd., we offer multiple sensor technologies to match diverse industrial needs:
- Catalytic combustion sensors – ideal for combustible gases in general industrial settings, with fast response and low cost. Our GDC series uses high-performance catalytic elements with anti-poisoning coatings for extended lifespan.
- Infrared (IR) sensors – highly accurate and immune to poisoning, suitable for harsh environments. The GDE series employs dual IR/laser technology with automatic temperature compensation and zero drift below 2% per six months.
- Electrochemical sensors – used for toxic gases like H2S, CO, and O2. Offers high specificity and stability.
- PID (Photoionization Detectors) – excellent for low-concentration VOCs in semiconductor and chemical plants.
- Semiconductor sensors – cost-effective for general-purpose monitoring in controlled environments.
For applications requiring long-term stability and minimal maintenance, infrared-based detectors like the GT-GDE820 and GT-GDC811 provide over 5 years of service life with ±3% measurement accuracy, making them ideal for oil refineries, petrochemical plants, and LNG facilities.
Detector Placement Around Equipment and Obstacles
Detectors must be placed near potential leak sources: flanges, valves, pumps, compressors, and storage tanks. A minimum of one detector per 25 m² is standard, but this increases to one per 9–16 m² in high-risk areas. Detectors should not be installed behind beams, ducts, or equipment that obstruct gas diffusion. In confined spaces, detectors must be placed at breathing level (1.5 m above floor) and near entry points for personnel.
For large open areas, a grid layout is effective. However, in complex layouts with multiple obstructions, a zoning strategy is preferred—dividing the space into smaller zones with dedicated detection coverage. This ensures no blind spots and allows for faster fault isolation.
Integration with Control Systems and IoT Platforms
Modern gas detection systems are no longer standalone devices. Our GM810/GM820 series gas alarm controllers support 4-20mA, RS485, and relay outputs, enabling seamless integration with DCS, SCADA, and fire alarm panels. With built-in automatic addressing and modular design, system expansion is straightforward and cost-effective.
For remote monitoring and predictive maintenance, our IoT cloud platform collects real-time data from detectors via 4G/WiFi modules. Alerts are sent to mobile clients, and historical trends are analyzed to detect early signs of sensor drift or environmental changes. This is particularly valuable in unmanned or hard-to-access areas.
All detectors in the GDE, GDC, and GDA series support pre-calibrated smart plug-in sensors, reducing downtime during replacement. The color LED display allows on-site configuration and status checks from up to 25 meters away, even in bright industrial environments.
Compliance with Zone Classification and Safety Standards
Fixed gas detectors in explosion zones must meet strict safety certifications. Our products are designed for Zone 1 and Zone 2 hazardous areas, with Exd IIC T6Gb and DIP A20 TA T6 ratings. They comply with GB15322-2003, GB3836-2010, and upcoming GB15322-201X standards, and hold CCC, CPA, and explosion-proof certifications.
Electrical interfaces use 3/4 NPT threaded entries for secure conduit connections. The housing is made of corrosion-resistant aluminum or stainless steel, rated IP66 for dust and water ingress protection. Operating temperature ranges from -40°C to +70°C, ensuring reliability in extreme climates.
For multi-gas monitoring in complex facilities, we recommend combining different sensor types within the same network. For example, pairing IR detectors for methane with electrochemical sensors for H2S in a wastewater treatment plant ensures comprehensive coverage.
Final Recommendations for System Design
When designing a fixed gas detection system, consider these key factors:
- Use IR-based detectors in areas with high risk of sensor poisoning or long-term exposure.
- Place detectors at multiple heights for mixed gas environments.
- Ensure all detectors are accessible for calibration and maintenance.
- Integrate with a central controller for centralized alarming and logging.
- Use wireless modules in retrofit projects to reduce cabling costs.
Shanghai Gewe Electronics provides full technical support from system design to commissioning. Our portfolio includes not only detectors and controllers but also flame detectors with AI-powered UV/IR technology, enabling integrated safety solutions for high-risk industries.