Executive Summary- Fire Sprinkler Systems
Automatic sprinklers are highly effective and reliable elements of total system designs for fire protection in buildings. According to the 2009 American Housing Survey, in 2009, 4.6% of occupied homes (including multi-unit) had sprinklers, up from 3.9% in 2007, and 18.5% of occupied home built in the previous four years had sprinklers.
Of reported 2007-2011 structure fires, an estimated 10% showed sprinklers present.* Sprinklers were reported as present in 57% of reported fires in health care properties. High-rise apartment buildings (47%), manufacturing facilities (48%), passenger terminals (51%), hotels and motels (52%), prisons and jails (53%), dormitories and barracks (53%), and high-rise office buildings (63%), all had sprinklers reported in roughly half or more of reported structure fires. In every other property uses, more than half of all reported fires were reported as sprinklers not present.
Sprinklers are still rare in educational properties (36% of fires), stores and offices (24%), public assembly properties (23%), and especially homes (6%), where most fire deaths occur. There is considerable potential for expanded use of sprinklers to reduce the loss of life and property to fire.
As defined in NFPA 13, section 3.4, a wet pipe sprinkler system has sprinklers attached to a piping system containing water so that water discharges immediately from sprinklers opened by heat from a fire, while a dry pipe sprinkler system has sprinklers attached to a piping system containing air or nitrogen under pressure so that sprinkler activation releases the air or nitrogen, allowing water pressure to open a valve and water to flow into the piping system and out the opened sprinklers. With wet-pipe sprinklers the fire death rate per 1,000 reported home structure fires was lower by 82% and the rate of property damage per reported home structure fire was lower by 68%. For more on NFPA’s Home Fire Sprinkler Initiative, go to http://www.firesprinklerinitiative.org.
Sprinkler systems are carefully designed to activate early in a real fire (responding to heat not smoke) but not to activate in a non-fire situation. Each sprinkler reacts only to the fire conditions in its area. Water release in a fire is generally much less than would occur if the fire department had to suppress the fire, because later action means more fire, which means more water is needed. Water release with no fire is rare compared to water release in response to a fire.
Sprinklers operated in 91% of all reported structure fires large enough to activate sprinklers, excluding buildings under construction and buildings without sprinklers in the fire area. When sprinklers operated, they were effective 96% of the time, resulting in a combined performance of operating effectively in 87% of all reported fires where sprinklers were present in the fire area and fire was large enough to activate them. The more widely used wet pipe sprinklers operated effectively 89% of the time, while dry pipe sprinklers operated effectively in 76% of cases.
* These estimates are projections based on the detailed information collected in Version 5.0 of the U.S. Fire Administration’s National Fire Incident Reporting System (NFIRS 5.0) and the NFPA’s annual fire department experience survey. In this report, fires are excluded if they involve buildings under construction or failure or ineffectiveness because of a lack of sprinklers in the fire area. Because fires reported as confined fires are usually reported without sprinkler performance details or as fires too small to activate operating equipment, confined fires are not included in any analysis involving reliability or effectiveness of automatic extinguishing equipment. See Appendixes A and B for additional details of statistical methodology, including the distinction between confined and non-confined fires.
When sprinklers fail to operate, the reason most often given (64% of failures) was shutoff of the system before fire began, as may occur in the course of routine inspection or maintenance. Other leading reasons included manual intervention that defeated the system (17%), lack of maintenance (6%), and inappropriate system for the type of fire (5%). Only 7% of sprinkler failures were attributed to component damage.
When sprinklers operate but are ineffective, the reason usually had to do with an insufficiency of water applied to the fire, either because water did not reach the fire (44% of cases of ineffective performance) or because not enough water was released (30% of cases of ineffective performances). Other leading reasons were system component damage (8%), manual intervention that defeated the system (7%), lack of maintenance (7%), and inappropriate system for the type of fire (5%).