Strategic Detector Placement in Steel and Smelting Workshops
In steel and smelting facilities, the risk of CO (carbon monoxide) and flammable gas accumulation is persistent due to high-temperature processes, incomplete combustion, and confined ventilation zones. Effective detection requires more than sensor accuracy—it demands a stratified placement strategy based on gas behavior, thermal dynamics, and operational workflows.
The primary goal is to position gas detectors at points where gases are most likely to concentrate before reaching hazardous levels. This involves analyzing gas density, airflow patterns, equipment layout, and thermal stratification.
Gas Behavior and Density-Based Zoning
CO and most flammable gases (e.g., methane, propane) have densities close to or slightly greater than air. However, in smelting environments, high temperatures alter gas behavior. Hot CO rises due to thermal buoyancy, forming stratified layers near ceilings and upper walls. Flammable gases from leaks or incomplete combustion may pool in low-lying areas if cooler, or rise rapidly in high-heat zones.
Detectors must be placed in **three vertical layers**:
- Upper layer (2/3 of room height): Targets hot CO and light hydrocarbons. Ideal for infrared (IR) or laser-based sensors with long-term stability.
- Mid-layer (1/2 height): Monitors transitional zones where gas mixes with ambient air. Suitable for catalytic or electrochemical sensors.
- Lower layer (near floor): Detects dense flammable gases like butane or propane, especially in enclosed pits or trenches.
For workshops with overhead cranes or ventilation systems, detectors should be offset from direct airflow paths to avoid false negatives. Stratified placement ensures early detection before gas spreads uniformly.
Thermal Stratification and Sensor Selection
High-temperature zones (e.g., near furnaces, ladles, or reheating units) create thermal plumes that lift gases vertically. In such areas, detectors must be installed at the **thermal interface**—where hot gases cool and begin to spread horizontally. This is typically 1–2 meters below the ceiling.
Sensor technology must match the environment:
- Infrared (IR) and laser sensors: Ideal for high-temperature zones due to resistance to thermal drift and long lifespan (5+ years). The GDE series from Shanghai Gewei Electronics uses IR/laser technology with auto-zeroing and temperature compensation, ensuring stable readings in fluctuating thermal conditions.
- Catalytic sensors: Effective in moderate-temperature zones but require frequent calibration. Use anti-poison variants in areas with silicon or sulfur exposure.
- Electrochemical sensors: Best for low-level CO detection in control rooms or maintenance areas, but avoid direct exposure to heat sources.
Sensor lifespan and drift characteristics must be factored into placement. For example, GDC series detectors use imported gas-sensing elements with zero drift <2% per six months, reducing maintenance frequency in hard-to-reach locations.
Networked Detection and Controller Integration
Modern steel workshops require integrated monitoring. Detectors must connect to a central gas alarm controller with real-time data aggregation. The GM810/GM820 series controllers from Gewei support RS485 and 4-20mA outputs, enabling up to 1.5km signal transmission with loop resistance up to 600Ω.
Controllers should be placed in control rooms or maintenance hubs, but with direct line-of-sight or low-latency communication to all detectors. Use modular bus architecture to reduce cabling and simplify expansion. The GM8 series features automatic addressing, eliminating manual configuration.
For large facilities, deploy a **tiered network**:
- Primary detectors at high-risk zones (furnaces, charging bays, tapping points)
- Secondary detectors along gas migration paths (hallways, stairwells)
- Tertiary detectors in administrative zones for early warning
All detectors should support pre-calibrated smart plug-in sensors, allowing quick replacement without field calibration. This is critical in 24/7 operations where downtime is costly.
Environmental Resilience and Compliance
Smelting environments present challenges: high humidity, dust, vibration, and corrosive byproducts. Detectors must have IP66 protection, explosion-proof certification (Exd IIC T6Gb), and resistance to electromagnetic interference (EMC compliant with GB16838).
The GDA series offers dust explosion-proof design and operates in temperatures from -40°C to 70°C, suitable for outdoor or unconditioned spaces. Use stainless steel enclosures in areas with high moisture or chemical exposure.
All detectors must support remote status monitoring via LED indicators (normal, fault, alarm) visible from 25 meters. This reduces inspection time and improves response speed.
Data Integration with IoT and Cloud Platforms
Beyond local alarms, data must feed into IoT and cloud platforms for predictive analytics and compliance reporting. Gewei’s cloud software integrates with 4G/WiFi modules, enabling real-time alerts via mobile clients.
Historical data from detectors can identify recurring leak patterns, equipment degradation, or ventilation inefficiencies. This supports proactive maintenance and regulatory audits.
Use relay outputs to trigger external devices: shutoff valves, exhaust fans, or flame detection systems if gas concentration approaches LEL (Lower Explosive Limit).