Sprinkler System Performance by the Numbers
A review of historical sprinkler system statistics reveals. The National Fire Protection Association (NFPA) publishes data summarizing sprinkler system performance on a frequent basis. From 1925 through 1969, the top five reasons for unsatisfactory sprinkler performance remain the same:
- Water shut off (35.4%)
- System not adequate for level of hazard in occupancy (13.5%)
- Inadequate water supplies (9.9%)
- Inadequate maintenance (8.4%)
- Obstruction to water distribution (8.2%)
- Partial sprinkler protection (8.1%)
- Faulty building construction (6.0%)
- System components defective or damaged (5.6 %)
- Exposure fire (1.7 %)
- System frozen (1.4%)
- Other (1.9%).
Reason Sprinkler Systems Fail to Control the Hazard
1.Failure to maintain operational status of the system.
The foundation of achieving satisfactory sprinkler performance is regular inspection, testing and maintenance of the sprinkler system and providing a system that is 100% operational before and during a fire event. This category includes instances where the water supply is shut off for any number of reasons prior to or during the fire event inadequate maintenance (including installation deficiencies not captured during acceptance testing or subsequent inspection, testing and maintenance procedures), component mechanical or corrosion failures, and obstructions to water distribution.
2. Failure to assure adequacy of system and/or for the complete coverage of current hazard.
A sprinkler system’s effectiveness during a fire event is bound by the design criteria of the original installation. The design criteria must be consistent with the protected hazard. A common cause of unsatisfactory sprinkler system performance is inappropriate design for the hazard protected. The inadequacy of a sprinkler system could stem from a number of reasons, including initial design errors, installation deficiencies, partial system designs, changes to the protected commodity in its configuration/quantity, and building changes in use or occupancy.
3. Defects affecting, but not involving, the sprinkler system.
The proper operation of a sprinkler system during a fire may depend on the function of other building systems and features. Unsatisfactory performance of the sprinkler system during a fire event could be caused by conditions or elements that are peripheral to, but not distinctly a part of, the sprinkler system i.e. reductions in available water supply to the protected building, faulty building construction and lack of compartmentation.
Sprinkler system designs are premised on the principle that the strength of the water distribution system available at the time of construction will remain within the original design buffer. However, the water supply strength can degrade over time. Increased nominal demand from new developments utilizing the same water infrastructure, closing of water infrastructure isolation valves and seasonal effects can result in diminished flow and/or pressure available to sprinkler systems. Water authorities may reduce water infrastructure working pressure to conserve water that is wasted due to leakage.
Defective building construction can render a sprinkler system inoperable. A common occurrence is the collapse of a building element used for support of sprinkler system components during a fire. The failure of a joist, beam, roof section or floor during a fire can rupture sprinkler system pipes, causing a loss of water pressure to the system and unsatisfactory performance of the sprinkler system.
4. Inadequate performance by the sprinkler system itself.
The proper operation of a sprinkler system during a fire depends on proper operation of the components. Although considered reliable, sprinkler system components can fail and adversely affect the operation of the entire system. Data has shown that these types of failures are a very small fraction of the overall reasons for failure.
Other causes that contribute to unsatisfactory performance of sprinkler systems include: exposure fires starting on the exterior of the building; delays associated with manual fire suppression efforts; general delays in notifying the fire department of a small incipient fire that rapidly grows to a catastrophic size; and other unknown causes. These causes are a relatively small fraction of the reported reasons for unsatisfactory sprinkler system performance.
Although rare, components of the sprinkler system itself (sprinklers, piping, valves, etc.) can either fail to activate, delay activation or decrease the available water supply needed to effectively control the fire. System component damage is the least frequently cited reason for unsatisfactory sprinkler system performance. This is consistent with the earlier statements that overall sprinkler system components are reliable. The data presented involving component damage of sprinkler equipment included incidents where the damage was a consequence of the fire, rather than a root cause of sprinkler system failure.
5. Other causes
Other Causes that contribute to unsatisfactory performance of sprinkler systems include: exposure fires starting on the exterior of the building; delays associated with manual fire suppression efforts; general delays in notifying the fire department of a small incipient fire that rapidly grows to a catastrophic size; and other unknown causes. These causes are a relatively small fraction of the reported reasons for unsatisfactory sprinkler system performance.