Fire sprinkler systems can fail in three functional ways. An inadvertent discharge can
occur if a system discharges water through the sprinklers when no fire is present. A fire sprinkler system can also leak water from a pipe, fitting, or head. The third way a fire sprinkler system can fail is when it does not deliver water to the sprinkler heads in the manner it was designed in the presence of a fire, and therefore does not control the fire.
Inadvertent sprinkler head activations are rare. They can occur when a fire sprinkler head is mechanically impacted, when the head becomes too hot, or if the fusible link in a system becomes damaged. Inadvertent fire sprinkler head activations typically occur to only one head at a time, limiting the total water discharged, which will often limit the damages. However, for sprinkler heads protecting high value areas, even the discharge from one sprinkler head can cause a large monetary loss.
Piping Leaks & Breaks
Fire protection piping systems are subject to pipe leaks and breaks just like any other piping system. However, sprinkler installation standards, such as NFPA 13, address this hazard by requiring protections and support of the piping. Maintenance standards, such as NFPA 25:
Standard for Inspection, Testing, and Maintenance of Water-based Fire Protection Systems require that these hangars be inspected routinely. None-the-less, leaks and breaks can still occur. One of the most common modes for leaks and breaks in sprinkler piping is freezing of water within the piping, expanding, and cracking or breaking the pipe. As such, it is imperative that wet pipe systems not be installed in unheated areas, and that such heat be maintained throughout cold weather. In the event a dry pipe system is installed, it must be properly installed and completely drained of water before the onset of freezing conditions.
Non-operation of Sprinkler System
Fire sprinkler systems are designed to detect a fire and then discharge water onto the fire to control it. If no water, or insufficient water, discharges from the sprinkler heads, the fire may continue to grow and cause further damage. There are numerous ways in which a fire sprinkler system can fail to operate effectively, including an obstruction in the piping, a closed valve in the water supply piping, or insufficient pressure from the water supply, among others. One primary purpose of the Inspection, Testing, and Maintenance standard for sprinkler systems (NFPA 25) is to inspect for, and correct, conditions which might result in non-operation on a regular basis.