Any one break is a random occurrence, but repetitive, reoccurring breaks suggests conditions within the pipe system are a danger and that actions should be taken to reduce or eliminate the risks. One of the most common conditions within a distribution system is Water Hammer. Also known as fluid hammer, water hammer is a pressure surge or wave that results when a fluid (water)is forced to stop or change direction suddenly (momentum change).
Water Hammer conditions occur most often during:
• Sudden Valve Closure (fire hydrants, power failure, etc.)
• Pump Failure
• Check Valve slam (due to sudden deceleration, a check valve may slam shut rapidly, depending upon the
• dynamic characteristic of the check valve and the mass of water between a check valve and tank).
• Rapid expulsion of air from a vent or partially open valve
• Unexpected pipe breaks or damage - construction damage, traffic accidents, ground shift
• Severe changed in elevation or grade
Distribution systems are exposed to water hammer and surge conditions and these two forces can result inexcessive vibration with-in the system, fitting failure, displacement and pipe wall ruptures (i.e. breaks).