As critical engineering infrastructures that overcome natural geographical barriers, tunnels play an irreplaceable role in optimizing transportation networks and promoting coordinated regional economic development. These “underground corridors” crossing mountains and seas not only reshape spatial and temporal distances but also serve as “mega-projects” supporting national strategies. However, as tunnels extend deep into the earth, a hidden crisis quietly emerges — gas safety.
Due to limited ventilation and complex geological conditions, tunnels are prone to the accumulation of various flammable, toxic, and hazardous gases, creating significant gas safety hazards. These mainly include the following categories:
Hazards of flammable gases: Methane, hydrogen, ethane, and other alkanes act as “powder kegs” in tunnels. Methane is commonly found in specific geological areas. When its concentration reaches the explosive limit, exposure to an open flame or high temperature can trigger a violent explosion with devastating power. When alkanes reach a certain concentration, an open flame can ignite them, causing fires that engulf the tunnel.
Hazards of toxic gases: Carbon monoxide, hydrogen sulfide, sulfur dioxide, nitrogen oxides, and ammonia are the “invisible assassins” inside tunnels. Carbon monoxide hinders oxygen transport, leading to hypoxia and unconsciousness. Hydrogen sulfide irritates the respiratory tract and eyes, and at high concentrations can be instantly fatal. Sulfur dioxide and nitrogen oxides cause long-term irritation to the respiratory tract, laying the groundwork for lung diseases. Ammonia attacks the skin and mucous membranes, damaging respiratory health.
Hazards of asphyxiating gases: Although carbon dioxide and methane differ in nature, excessive accumulation of either reduces oxygen concentration in the air, causing chest tightness, breathing difficulties, and eventually unconsciousness. Large amounts of methane can cause hypoxic asphyxiation.
Combined hazards: Tunnel fire smoke is a “mixture” of multiple toxic gases. Carbon monoxide, carbon dioxide, particulate matter, hydrogen cyanide, hydrogen chloride, and others act synergistically, causing chemical burns and organ damage. Particulate matter harms the respiratory tract, while high temperatures and hypoxia exacerbate physical stress. Dense smoke also obstructs escape routes. The combination of multiple factors accelerates the collapse of human bodily functions, potentially leading to unconsciousness and death within a short time.
01 Technology Builds a Safety Defense Line for Tunnels
In the face of serious tunnel gas hazards, deploying gas detectors has become a key measure to ensure safe tunnel operation. To address gas safety challenges and relevant requirements, Chicheng Electric has built an “impenetrable fortress” for tunnel gas safety with “precise sensing, intelligent warning, and rapid response” at its core, using high-performance gas detectors.
02 Selection of Gas Detector Installation Locations
Gas monitoring points in tunnels should be located in high-risk areas where gas leaks are likely to occur, such as tunnel entrances, tunnel midpoints, tunnel bifurcations, tunnel excavation faces, and near blasting zones. These locations are high-risk areas for gas leakage. Installing detection instruments at these points enables timely identification and handling of potential gas safety hazards.
Gas Detector Installation Requirements
Number and layout of installations: The number and layout of detection instruments should be reasonably determined based on the specific tunnel conditions, gas detection requirements, cost, and other factors.
Installation height: The installation height of detection instruments should be determined according to the specific gravity of the gas being monitored. For gases lighter than air, sensors should be installed at or near the tunnel ceiling. For gases heavier than air, sensors should be installed close to the ground. To ensure normal operation and prevent water splashes, the installation height should be greater than 30 cm.
03 Portable Gas Detectors
In addition to deploying fixed gas detectors, carrying portable gas detectors during tunnel operations is also an important safety measure. As the tunnel engineering sector continuously pursues safe and efficient development, Chicheng Electric, leveraging its deep technical expertise, has launched portable gas detectors that integrate advanced detection technology, high environmental adaptability, user-friendly design, comprehensive safety protection, and intelligent management functions. These devices not only provide reliable life safety protection for tunnel workers but also reduce the risk of tunnel accidents at the societal level, contributing significantly to public safety and social harmony and stability.
BTYQ-B30 Composite Gas Detector Alarm
16-bit high-precision front-end ADC acquisition module
UCGUI graphical engine for optimized human-machine interface
Full-function self-test at startup: sensor, battery level, circuit, and alarm functions
Three-proof design: waterproof, dustproof, and explosion-proof
Two-level (low alarm, high alarm) triple alarm (sound, light, vibration)
GC610 Composite Gas Detector
Simultaneous detection of six gas leakage concentrations
High-sensitivity sensors with high accuracy and fast response
360-degree safety drop protection design, durable and impact-resistant
Full certifications; effective dustproof, waterproof, and explosion-proof
GC310 Composite Gas Detector
Supports detection of 1, 2, 3, or 4 gases
Sound, light, and vibration triple alarm
Compact, lightweight, sturdy, and drop-resistant
Waterproof, dustproof, and explosion-proof, suitable for confined spaces
GC510 Portable Gas Detector
Available in pump-suction and probe-gun styles
Imported sensors with fast sampling speed
High-strength ABS engineering plastic; waterproof, dustproof, slip-resistant, and explosion-proof
2800mA rechargeable lithium battery with ultra-long standby time
04 How to Self-Rescue in a Tunnel Accident
Stay calm: Panic accelerates oxygen consumption and increases the risk of inhaling toxic smoke.
Move in a low posture: Toxic smoke rises upward; the air near the ground is relatively fresher.
Cover your mouth and nose: Use a wet towel or clothing to cover your mouth and nose to reduce inhalation of toxic gases.
Find an escape route: Follow escape signs and evacuate via cross-passages or the nearest exit.
Do not turn back: Once evacuated, do not return to retrieve belongings or look for others.
Report the incident promptly: Call the fire department immediately after reaching a safe area.
As underground arteries of cities, tunnel gas safety is vital to human life and facility stability. Chicheng Electric will continue to safeguard gas safety, empowering the tunnel industry with technology to build a solid safety defense line.
