What is an Explosion-Proof Water Bag? – An Essential Safety Device for
Underground Coal Mine Explosion Prevention
1. Definition and Function of an Explosion-Proof Water Bag
An explosion-proof water bag is a safety device installed in underground coal mines, specifically designed to prevent the propagation of gas explosions and coal dust explosions.
It is typically made of high-strength plastic-coated fabric with flame-retardant, anti-static, and corrosion-resistant properties, and complies with MT157 national industry standards.
When an explosion occurs, the water bag ruptures instantly under the impact of the blast wave, releasing a large amount of water mist. This mist forms a barrier that covers the entire tunnel cross-section, effectively absorbing explosive energy, reducing temperature, and blocking the spread of flames, thereby minimizing damage to personnel, equipment, and ventilation systems.
2. Specifications and Performance Parameters
Common models include GD/20L, GD/30L, GD/40L, GD/60L, and GD/80L, selected according to the cross-sectional area of the roadway and protection requirements.
Key performance indicators:
- Flame-retardant performance: Strictly complies with MT157-1996 standard
- Surface resistance: ≤ 3×10⁸ Ω
- Water mist formation time: < 150 ms
- Water mist duration: > 160 ms
- Mist diffusion range: Length > 5 m, width > 3.5 m, height ≈ 3 m
These parameters ensure that the water bag can respond quickly and effectively when an explosion occurs.
3. Installation Methods and Technical Requirements
Explosion-proof water bags are typically installed in the form of water bag barriers in straight underground roadways.
Installation guidelines:
- Water capacity configuration
- Main barrier: ≥ 400 L/m²
- Auxiliary barrier: ≥ 200 L/m²
- Barrier length
- Main barrier: ≥ 30 m
- Auxiliary barrier: ≥ 20 m
- Hanging method
- Use double-row hooks or Φ4–8 mm round steel hooks
- Hook spacing ≤ 1.5 m
- Distance from the edge to the roadway wall ≥ 10 cm
- Bottom distance from the track surface ≥ 1.8 m
- Positioning requirements
- Install in straight roadways, 50–70 m away from intersections
- Maintenance checks
- Weekly inspection for water volume and damage
- Replace water if 5% dust contamination is detected
4. Packaging, Transportation, and Storage Requirements
- Markings: Each water bag must have a nameplate, safety mark, and serial number; packaging must display manufacturer name, product specification, quantity, and production date.
- Packaging contents: Packing list and product certificate of conformity.
- Transportation: Must comply with railway and road transport regulations; avoid mechanical damage.
- Storage: Keep in a well-ventilated warehouse, avoid direct sunlight and chemical corrosion.
5. Factors Affecting Explosion-Suppression Performance
The effectiveness of an explosion-proof water bag depends not only on product quality but also on explosion conditions and installation environment:
- Explosion source conditions: Location of ignition, energy of detonation, and gas/dust concentration directly influence blast wave and flame intensity. Coal dust explosions are generally stronger than gas explosions.
- Propagation conditions: Roadway cross-section, shape, obstacles, bends, and junctions affect flame spread speed and blast pressure.
- Installation quality: Improper installation, incorrect distance from the explosion source, or insufficient mist dispersion time may cause failure.
6. Common Causes of Failure
- Insufficient blast wave pressure: The pressure is too low to trigger the water bag.
- Mismatch in arrival time: The flame arrives before the mist is fully dispersed or after it has settled.
- Explosion source too far: The flame extinguishes before reaching the barrier, rendering it ineffective.
7. Application Scenarios and Safety Importance
Explosion-proof water bags are widely used in coal mining faces, transportation roadways, and return airways.
They form an essential part of the mine’s explosion prevention system, working alongside gas monitoring systems, ventilation systems, and explosion-proof water troughs to create multi-layer protection.
The most important role of the water bag is to interrupt the chain of explosion propagation in its early stage, thereby reducing casualties and economic losses.
8. Conclusion
What is an explosion-proof water bag?
It is far more than just a water container — it is a lifeline in underground coal mining against gas and coal dust explosions.
With proper selection, correct installation, and regular maintenance, explosion-proof water bags can play a crucial role in protecting lives and ensuring safe coal mine operations.
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