An effective Spark detection system must monitor all potential paths of a spark or ember through all branches of ducts and once a spark or ember is detected, it must establish a curtain of water through which the spark must pass. Air transport speeds of 6000 ft/min. are not uncommon which means a spark can be carried 100 feet in one second. Detecting the spark, turning on the water and establishing a spray curtain across the entire duct can take as much .288 seconds or .0048 minutes. A well designed, reliable and rapid response system is required.