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Residential Sprinkler Systems

NFPA Journal®,   November/December 2007

By Art Cote, P.E., FSFPE

In his landmark book, Automatic Sprinkler Protection, Gorham Dana, manager of the Underwriters’ Bureau of New England, wrote in 1914, “It is a noteworthy fact that in all the fires in sprinklered buildings, there has been practically no loss of life. This being the case, it is indeed strange that the sprinkler has not been more frequently installed as a life saver.”

While it took longer than Dana envisioned, sprinklers are installed and required in many occupancies, including homes in some jurisdictions.

An impetus for change included a decision in 1973, by President Richard Nixon to appoint the Presidential Commission on Fire Prevention and Control to study the American fire problem.

The commission’s landmark report America Burning set a goal of reducing the U.S. fire death toll by 50 percent in a generation. In response to America Burning, the NFPA Automatic Sprinkler Committee formed the NFPA 13 Residential Sprinkler Subcommittee. The subcommittee’s work led to the development of the first edition of NFPA 13D,   Sprinkler Systems in One- and Two-Family Dwellings and Mobile Homes, in 1975.

The standard was based on the collective experience of the committee members, not on fire testing. Based on a review of fire incident data, NFPA’s Technical Committee on Sprinkler Systems developed a residential sprinkler installation standard. The standard covered the principally occupied areas of a dwelling and met the goals of preventing flashover, providing sufficient time for safe egress or rescue and economic viability.

To keep costs down, the Technical Committee proposed that sprinklers be located only in occupied rooms. For this reason, sprinklers were not required in small bathrooms, small closets, attics not used as a living space, porches, carports, garages and foyers.

Beginning in 1976, the USFA supported a significant number of research programs on a variety of topics relating to residential sprinkler systems. The objective of the USFA research program was to assess the impact sprinklers would have on reducing deaths and injuries in residential fires.

The USFA worked in conjunction with the NFPA, Factory Mutual Research Corp., Underwriters’ Laboratories and others to achieve reliable and acceptable systems, the minimum water discharge rates and automatic sprinkler flow required and response sensitivity and design criteria.

Although researchers at Factory Mutual recognized the need for “faster” or more “sensitive” sprinklers as early as 1884 in tests conducted by C.J.H. Woodbury, it was not until the late 1960s that a “quick-response sprinkler” subcommittee was formed within the NFPA Sprinkler Committee. With regard to speed and sensitivity, the sprinkler of the 1970s changed little from its earlier incarnations.

USFA-sponsored research showed that a more sensitive sprinkler was needed to respond faster to smoldering and fast-developing home fires. First, fires had to be controlled quickly in order to prevent the development of lethal conditions in typically small home compartments. Second, fires had to be attacked while still small if they were to be controlled with the water supplies typically available in single-family dwellings (20 to 30 gallons per minute).

Research resulted in the development of a prototype fast-response sprinkler that could control or suppress typical residential fires with the operation of not more than two sprinklers. It could also operate fast enough to maintain survivable conditions within the room of origin. Thus, the design of the sprinkler itself expanded from the traditional role of property protection to include life safety.

Organizations continued to team up to conduct further testing. NFPA, FMRC and the Los Angeles Fire Department conducted full-scale field tests in a dwelling in Los Angeles  and in a mobile home in North Carolina . The NFPA Sprinkler Committee studied the research data and used it to establish the criteria for the 1980 edition of NFPA 13D, which for the first time required that only “listed residential sprinklers.”

In the nearly 30 years following the development of the residential sprinkler, special listings involving expanded protection areas and reduced flows proliferated to the point that the original flow and spacing criteria have become all but obsolete. Residential sprinklers are now listed for coverage areas up to 400 square feet (37 square meters) per sprinkler.

To address the issue of multifamily occupancies, NFPA 13R, Sprinkler Systems in Residential Occupancies Up to and Including Four Stories in Height, was introduced in 1989. It used the same concept of fast-response sprinkler technology contained in NFPA 13D, but with a maximum of four sprinklers flowing rather than two.

New developments in residential sprinkler system technology continued to increase the ease of installation and reduce the cost while maintaining system effectiveness and reliability. The technology includes the introduction of plastic piping systems that have been listed for residential use and the use of multipurpose systems. Multipurpose systems use the piping to supply domestic fixtures and sprinklers to reduce overall materials cost.

In 1996, the Home Fire Sprinkler Coalition was formed to provide information about the life-saving value of home fire sprinkler protection. In 2006, NFPA 101®, Life Safety Code®, became the first code in the nation to require sprinklers in new one- and two-family dwellings.