Infrared cuts dust explosion risk

Five elements are necessary for a dust explosion: ignitable dust; suspension of the dust into a cloud (in sufficient concentration); confinement; oxidant (usually air); and ignition.

Take any one of these away and there can be no explosion.

That's the concept behind the latest infrared heat detection equipment, which detects and removes hot bodies before they can contribute to a blast.

The latest breed of fire and dust explosion prevention systems such as the Firefly seek heat sources.

This reacts to temperatures as low as 250°C - well below the almost 700°C threshold of traditional spark detectors. The detector measures both the number of glowing particles and the highest registered energy value.

The system can detect and neutralise ignition sources within 100-300 ms. Water, the most common extinguishing agent, is sprayed under high pressure through full-cone nozzles throughout the extinguishing zone.

Carbon dioxide and nitrogen extinguishing agents, when indicated, are regulated using high-speed actuators with closure times from 50-300 ms. Mechanical diversion involves a switching valve that rapidly routes any abnormally hot material off the process conveyor into an isolated container. The process itself need not be stopped.