The System
System Operation
A spark detection system is composed of three basic components. First is the detector, which is highly sensitive to optical radiation emitted by hot or burning particles. The detector receives an optical signal and converts it into an electronic signal. The electronic signal is received and processed by the central control unit, which in turn triggers the extinguishing system. The three components: 1. Central Control, 2. Detector, and 3. Extinguisher are all integral parts of a successful spark detection and extinguishing system.
A spark detection system is typically used in pneumatic particle transport systems where there is potential for combustion or explosions. These include wood chips, cellulosic fibers, sawdust, chemical dust, combustible vapors and any other combustible material.
The detector reacts to rapid changes in the optical signal, so it is especially suited for viewing a cross section of a duct where the particles are in the field of view for only a short period of time. The purpose of the system is to provide a zone in the path of transport where no potentially hazardous spark can pass without being seen by the detector or detectors. Usually, two or more detectors must be used in order to ensure that the entire cross section of the transport zone is within the field of view of at least one detector.
The extinguishing system used is a solenoid operated water spray located downstream from the detection zone. The water spray is set up to create a curtain through which the hazardous particle must pass. The Spark Detection controller provides the essential timing and the impulse to open the solenoid valve for a fixed period of time during which we are ensured that the spark has passed through the curtain of water. The timing is important, as the activation of the spray must not be too late as it will miss the spark. Also, to avoid unnecessary shut down and cleanup, the spray must not be too long.
