The National Fire Protection Association’s study, U.S. Experience With Sprinklers, shows that fire sprinkler systems are only effective about 90% of the time. By reviewing fire loss data, examining investigative fire reports, and researching fire and building history, the National Fire Protection Association was able to catalogue all the reasons that fire sprinklers fail. The majority of fire sprinkler failures fall into one of these four categories:
- Failure to maintain operational status of the system.
- Failure to assure adequacy of system and/or the complete coverage of the current hazard.
- Defects affecting, but not involving, the sprinkler system.
- Inadequate performance by the sprinkler system itself.
Failure to maintain operational status of the system. It goes without saying, an adequate water supply is an essential and critical part of any sprinkler system. Yet, this is the primary cause of fire sprinkler failure. The water supply valve could be shut-down for any variety of reasons, including routine maintenance, building construction/demolition, system impairment, or improper valve installation. With any portion of the sprinkler system out of service (for any length of time), the smallest fire will quickly grow beyond the sprinkler systems capabilities.
Failure to assure adequacy of the system or complete and accurate coverage of the current hazard. Every sprinkler system is designed to protect a certain type of hazard based on a buildings proposed use. Over time the use of the facility, or certain areas of, may change, or the hazard may increase due to the types of material being used or stored. A sprinkler system designed for an ordinary hazard will quickly be overcome and disabled against a fire involving high hazard contents.
Defects affecting, but not involving, the sprinkler system. These include changes to the water distribution system, faulty building construction, and lack of compartmentation. R. Thomas Long, Jr., P.E. in his article for Fire Protection Engineering states,
Compartmentation of hazards through the use of fire barriers and walls is a fire protection strategy in itself, but physical separations can play a role in the effectiveness of the sprinkler system. High hazard areas in buildings can be segregated by fire-resistance-rated construction. The concept is to contain the fire in the compartment and prevent spread outward…Vigilance is necessary in maintaining passive fire protection compartmentation, not only to prevent the spread of fire, but to also improve the effectiveness of the sprinkler system in the area of fire involvement.
Inadequate performance by the sprinkler system itself. This is the most rare cause of fire sprinkler system failure, a defect in the system itself, component damage, or failure to properly activate. These incidents most commonly occur as a consequence of a fire. Overall sprinkler system components are extremely reliable.
With a fire sprinkler success rate of only 90%, there is only one solution for protecting those that “are not capable of self preservation”, balanced fire protection. We need fire sprinkler systems, we need fire rated wall and corridor assemblies, and we must maintain smoke barriers. It is only in this balanced approach to fire protection that makes survivability in fire emergencies possible.