Fire Safety Science Digital Archive

Thousands of sprinkler heads, which have been sampled from in-service sprinkler systems, were tested by Fire Systems Group (FSG) of Industrial & Research Services (IRS) of CSIRO in accordance with the requirements of Australian Standard AS 1851: Part 3 (Maintenance of fire protection equipment - Automatic fire sprinkler systems) and SSL Test Specification FTS-123. During the course of this testing FSG investigated causes of test failures of the sprinkler head samples. The results of these investigations indicated that the main reasons for failure of used sprinkler heads were: adding sodium silicate (“waterglass” or “egg preserver”) to the system in order to overcome small leaks; “intergranular” corrosion of the lead-tin-bismuth “eutectic solder,” which fastens together the two halves of the fusible link; extensive deposit of paint on the deflector and the glass bulb or fusible link; heavy build-up of dirt and debris on the frame, heat-sensitive element and deflector; adhesion of the orifice disc to its seat, due to “glue-like” deposits of corrosion product; and deep deposits of hardened sediment or heavy build-up of water hardness salts above the orifice disc.