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The Evolution of Seismic Design of Fire Sprinkler Systems Russell P. Fleming, P.E. Executive Vice President National Fire Sprinkler Association Patterson, NY Special fire sprinkler system installation guidance intended to guard against damage due to earthquakes first appeared in the North American sprinkler installation standard in 1947, and was largely based on experience in the Long Beach earthquake of 1930. At that time many building codes in use in the United States did not even address the subject of earthquakes. Insurance reports of the Long Beach earthquake had indicated 90 damaged sprinkler systems. The first guidance, contained only in the appendix, called for 1 to 2 inches clearance around pipes, flexible couplings in risers and “some form of lateral and longitudinal bracing” for feed and cross mains. In the 1951 edition requirements were placed in the body of the standard for placement of longitudinal and lateral braces with spacing indicated as “30 to 40 ft”, a maximum slenderness ratio of brace members of 200, and flexible couplings on risers where it was necessary to protect systems against earthquakes. The stated intent was to laterally brace for 50% of weight of water-filled piping and attachments. In the decades since then deliberate efforts have been made to clarify the rules and improve protection within the text of NFPA 13 – Installation of Sprinkler Systems, but always with the intent of addressing “how” systems are to be protected against earthquakes, not “where” such protection is to be provided. It was recognized that building codes and other authorities made the basic decisions with regard to the location of earthquake-prone areas. Although the earliest guidance contained in NFPA 13 came from the insurance industry in the western states, the NFPA Committee on Automatic Sprinklers formed an Earthquake Protection Subcommittee in 1985. One of the goals of this subcommittee was to develop a means to address the bracing