This standard applies to systems for protection of ducting, conveyors or chutes used in pneumatic materials handling systems and most often used in the woodworking and textile industries. Other installation types may also be applicable. Spark radiation detectors are mounted to view in the duct to sense ignition sources. These detectors send signals to a control device, which in turn actuates a valve for a predetermined extinguishing cycle. The valve supplies one or more water-spray nozzles mounted downstream of the detectors; the water discharge is timed to ensure suppression of the ignition source and the material shortly before and after the particle. Because such a system is intended only for protection from a specific hazard, it should not be considered a substitute for general fire protection, including appropriate sprinkler protection.