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T he ongoing debate over residential1 fire sprinkler systems often includes more heat than light. Emotions run high on all sides of the discussion and, unfortunately, when sentiments take over, reasoned analysis often goes out the window. “If residential sprinklers are required, there will never be another new home built in this part of the state.” “If residential sprinklers aren’t required, people are going to die.” “Residential sprinklers cost too much.” “Residential sprinklers cost less than the carpet or granite countertops in a new home.” “Residential sprinklers are too complicated for the average homeowner and require costly maintenance.” Regardless of one’s position on the topic, it’s evident there is a lot of misinformation and misunderstanding about residential sprinklers. This primer may help people appreciate what goes into system design and installation. DESIGN CONSIDERATIONS Residential fire sprinkler design and installation are nowhere near as complex or sophisticated as systems that protect commercial properties. In fact, the residential sprinkler standards—International Residential Code (IRC) P2904 and National Fire Protection Association 13D—can be read and applied in a short period of time. When the technical committee created NFPA 13D in 1975, its goal was to promote affordable home fire protection. The basic elements are remarkably similar to, and less complex than, a modern home plumbing system. All one needs to satisfy the code is a reliable water supply, a pipe network to carry the water to the sprinklers, a single drain outlet and fire sprinklers installed in normally occupied rooms. Once installed, there is no required maintenance, although a responsible homeowner or tenant should check their system periodically,2 just as one should check furnaces, water heaters, air conditioning and other appliances to assure they are in good working order. Water supplies must be capable of operating the sprinkler system at about 26 gallons per minute (gpm) from 7 to 10 minutes,3 depending upon the size of the dwelling. In no case is the water supply required to exceed this amount. Water supplies can include municipal or private water purveyor connections (generally the most reliable), small water tanks with simple electric pumps, pressurized tanks that expel water when the sprinkler system operates, or—for rural areas—upsized domestic well casings, or a combination of tanks and well casings. Standby or emergency power to operate electric pumps is not required based on the assumption that a simultaneous power outage and fire—while possible—is statistically very unlikely to occur. Concerns about pipes freezing can be ameliorated by thoughtful placement of sprinkler pipe in interior walls, adequate attic insulation and, in extreme cases, adding food-grade glycerin to the water to create an anti-freeze solution.4 SPRINKLER PIPE There are a variety of products that may be used for residential sprinkler pipe: steel, copper, post-chlorinated polyvinylchloride (CPVC) and cross-linked polyethylene (PEX). Other than steel, these products are common on any jobsite for domestic water distribution systems. Depending on material, system design and water supplies, pipe sizes typically range from ½-inch for some PEX systems to 2-inch for the other materials. Larger pipe sizes are extremely rare, but may be found in high-end “mega-mansions” or other very large dwellings. The two predominant sprinkler system designs are “standalone” and OCTOBER 2016 | 24


October_2016_BSJ
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