Sprinklers operation automatically in the area of fire origin, preventing a fire from growing undetected to a dangerous size, while simultaneously sounding an alarm.
Automatic fire sprinklers keep fires small. The majority of fires in sprinklered buildings are handled by one or two sprinklers.
Automatic fire sprinklers are individually heat-activated, and tied into a network of piping with water under pressure. When the heat of a fire raises the sprinkler temperature to its operating point (usually 165°F), a solder link will will melt or a liquid-filled glass bulb will shatter to open that single sprinkler, releasing water directly over the source of the heat.
Contrary to what is sometimes shown on television sitcoms, all sprinklers in the building do not operate simultaneously. Sprinklers distribute water directly where it is needed to confine and control a fire. In the majority of fires, only one or two sprinklers are required to operate.
The likelihood of a sprinkler discharging water in the absence of a fire is very small. Each model of sprinkler is subjected to rigorous laboratory tests to guarantee long-term integrity, and every single sprinkler is hydrostatically tested at twice the maximum system water pressure prior to leaving the factory.
Lost records of Factory Mutual Research indicate that the probability of a standard response spray sprinkler discharging accidentally due to a manufacturing defect is only 1 in 16,000,000 sprinklers per year in service.
All fire protection features have a reliability factor. Walls and shafts can be breached by means of poke-throughs and building alterations. Exit doors can be blocked or locked.
Sprinklers may be the most reliable fire protection system known. Detailed fire records for Australia and New Zealand (where fire must be reported) for the years 1886 through 1968 showed that 99.76% of all fires were extinguished or controlled by the sprinklers. Fire records in this country are less dependable due to lack of full reporting, especially for small fires where sprinklers are successful. Nevertheless, the range includes a 96.2% success record reported by the National Fire Protection Association for the years 1925 through 1969, 98.4% success record for New York City high-rise buildings between 1969 and 1978, and a 98.2% success record for the U.S. department of Energy facilities between 1952 and 1980.
Because sprinklers attack the fire while it is still small, the total amount of water needed for fire suppression is small, often less than 50 gallons per minute. If the fire is permitted to grow, the fire department will typically apply hundreds of gallons of water per minute during their operations. For this reason, total amounts of water used in sprinklered buildings approximate one-tenth the amounts used in fires in non-sprinklered buildings.
Aside from fire fighting and explosion fatalities, there has never been a multiple loss of life in a fully sprinklered building due to fire or smoke. Individual lives have been lost when the victim or his clothing or immediate surroundings became the source of the fire.
A National Fire Protection Association study for the years 1971 – 1975 found that approximately 20 lives are lost each year in this country in sprinklered buildings, as compared to approximately 4,000 per year in unsprinklered buildings. Some 68%of the lives lost in sprinklered buildings were due to explosions, and an additional 18% were due to the fact that the fire originated in an unsprinklered area of the building.
All sprinklers installed in conformance with National Fire Protection Association (NFPA) standards must be listed. A listing basically means that the manufacturer has successfully submitted the product to an independent laboratory for testing against an established standard of quality. Both Underwriters Laboratories and Factory Mutual Research have established special listing categories for fire sprinklers.
Quick response sprinklers are those which are tested under the same product testing criteria as standard sprinklers, but also exhibit the fast response characteristics of listed residential sprinklers. Some manufacturers developed these sprinklers by inserting the residential sprinkler operating mechanism into a standard sprinkler frame. Other manufacturers successfully submitted residential sprinklers to the laboratory for testing under the criteria for standard sprinklers. In both cases, Underwriters Laboratories designated these special sprinklers as quick response sprinklers. By establishing a separate listing category, UL has identified listed quick response sprinklers as being different from both standard and residential sprinklers. Unlike the residential sprinklers, quick response sprinklers are not required to have special cooling and distribution abilities.
The system cost can often be offset by insurance savings, and by specific design alternatives or “trade-offs” permitted by most building codes in view of the superior protection afforded by sprinklers. These trade-offs often include reduced fire-resistant requirements for structural components, longer exit travel distances, and larger building areas and heights.
The National Fire Protection Association publishes NFPA 25 Inspection, Testing and Maintenance of Water-Based Fire Protection Systems. This document recommends that control valves without electronic supervision be checked on a weekly basis, just to make sure that they are in the open position. Other system components have different requirements. Check with the NFPA 25 or manufacturers’ literature for details.
At least four times each year, a full sprinkler system inspection should be performed by a knowledgeable professional. Some states and cities require more frequent inspections. Most sprinkler contractors offer economical long-term service agreements. These contractors can provide you with the test certificates which will comply with your insurance company and local fire department inspection requirements.
Recent court decisions have held building owners and managers liable because they did not have a fire sprinkler system in a building which had a fire. Even though sprinkler systems were not required in these buildings by fire or building codes, owners still had to pay out millions of dollars. Similarly, an owner or manager of a building with a fire sprinkler system would be held liable if he failed to maintain that system in working condition.
In addition, owners and managers of commercial and business facilities have an obligation to maintain safe conditions for employees and occupants. By workin gin a sprinklered building, employees come to expect a certain level of protection. It is incumbent on the owner to maintain this level of protection.