Safety Level

Spark Extinguishing Systems: Safeguarding Pneumatic Conveying Against Fire and Explosion

 

Spark extinguishing systems are specialized fire protection systems designed to detect and suppress ignition sources—specifically sparks, glowing embers, or hot particles—traveling within pneumatic conveying or dust extraction ductwork.1 These systems are crucial in industries handling combustible materials where the risk of dust explosions or fires initiated by these transient heat sources is high.2

 

🧐 Function: Detection of Initial Ignition

 

The core function of a spark extinguishing system is the ultra-fast detection of an initial ignition source before it reaches a filter, silo, or other container holding a large volume of combustible material.3

 

  1. Spark Detectors: Highly sensitive infrared (IR) sensors or detectors are installed within the ductwork.4 These detectors are designed to register the specific infrared radiation emitted by a hot, glowing, or incandescent particle as it passes through their field of view.5

     

  2. Rapid Response: Unlike conventional smoke or heat detectors, spark detectors boast an extremely fast response time, often in the millisecond range.6 This speed is essential because the particles are traveling at the high velocities associated with pneumatic transport (e.g., 20–30 m/s).

     

  3. Signal Transmission: Upon detection, the sensor immediately transmits a signal to a dedicated, high-speed control console. The control console verifies the signal and initiates the extinguishing sequence.

💧 Automatic Water Curtain Extinguishing Mechanism

 

The extinguishing mechanism relies on creating a high-velocity water curtain downstream from the detection point, which instantly cools and extinguishes the hot particle.7

 

  1. Valve Activation: The control console triggers a specialized, fast-opening high-speed solenoid valve connected to a pressurized water supply line.8

     

  2. Nozzle Discharge: This valve rapidly releases water into a series of strategically placed extinguishing nozzles within the duct.

  3. Water Curtain Formation: The nozzles are designed to create a finely atomized spray—a dense, uniform curtain of water mist—that completely encompasses the interior cross-section of the duct.9

     

  4. Instant Suppression: As the high-speed spark or ember passes through this water curtain, it is quenched and cooled below its ignition temperature in a fraction of a second, preventing it from causing a secondary, much larger fire or dust explosion upon reaching the storage or collection area.

Crucially, the entire process—from detection to full water discharge—can take less than 100 milliseconds, ensuring the spark is extinguished before it travels a significant distance.

🏭 Recommended Applications

 

Spark extinguishing systems are recommended for any industrial process that involves the pneumatic conveying or dust extraction of materials that present a high risk of dust explosion (Kst values) or fire, especially those processes known to generate sparks.

Application Area High-Risk Materials Ignition Source
Wood Industry Wood dust, chips, shavings (MDF, particle board) Mechanical friction, foreign bodies (stones, metal) in grinders/saws
Food & Feed Industry Flour, sugar, starch, cocoa, grain dust Grain handling, grinding, sieving
Textile Industry Cotton, synthetic fibers Friction, broken machine parts
Chemical/Pharmaceutical Pharmaceutical powders, certain plastic dusts, pigments Electrostatic discharge, milling
Recycling/Waste Paper, cardboard, mixed plastic waste Foreign metal objects hitting fans, shredders
Metal Processing Aluminum, magnesium dust Mechanical grinding, cutting operations

These systems are most effective when applied to the transport lines leading to:

  • Dust Collectors/Filters: Preventing fire in the filter media, which is often a source of high surface area and concentrated fuel load.

  • Silos and Bins: Preventing fires or explosions in large storage vessels.10

     

  • Production Machines: Protecting downstream processes like sanding machines or dryers from internal fire spread.