American Fire Sprinkler Association 12750 Merit Dr., Suite 350 Dallas TX 75251
Ph:(214) 349-5965 Fax:(214) 276-0908 ------------------------------------ TECHNICAL UPDATE MARCH 26, 2009 ------------------------------------ I have a situation where there is a stair with approximately 70 ft elevation difference between the lowest and highest landing. The stair is open where there are no walls around it and is exposed to the atrium and other areas of the building. The sprinklers serving the stair are served from a control valve off the atrium sprinklers at the high roof level. How do you properly size the pipe for the sprinklers serving the stair? Would the pipe serving the sprinklers for the stair fall under 11.2.3.4.2 and calculate only seven of the 10 sprinklers operating since the stair is not enclosed? We have reviewed NFPA 13, 2002 Edition that you indicated as the applicable standard. Our informal interpretation is that the stair should be treated as a special design area. Section 8.14.17 indicates that stairs, towers, or other construction with incomplete floors, if piped on independent risers, shall be treated as one area with reference to pipe sizes. The commentary for 8.14.17 indicates that stair towers can open a large percentage of sprinklers in the area. An independent riser supplying a stair or tower must be sized to supply all the sprinklers. Since your application has the stairs open to the atrium, sizing the pipe to all sprinklers operating does not apply. The most logical method for an open stair is to treat it as one area since the stair is piped with a single line from the top and is independent of each floor. It is not likely to activate many heads in this open stair application. Thus using Section 11.2.3.4.2 for special design areas to calculate all sprinklers on the line up to a maximum of seven would apply. ----------------- Technical Update is prepared by the Technical Services Dept. of the AFSA: Vice President of Engineering and Technical Services Roland Huggins, a PE registered in fire protection engineering; Phill Brown, a NICET IV certified automatic sprinkler technician and NFPA Certified Fire Protection Specialist (CFPS) and Tom Wellen, a degreed fire protection engineering technologist. This is provided with the understanding that the AFSA assumes no liability for this opinion or actions taken on it and they are not to be considered the official position of the NFPA or its technical committees. Copyright © 2009, American Fire Sprinkler Association. All Rights Reserved -------------------------- If you╒d rather not receive future faxes from AFSA, fax your removal request to Amy Sweeney at efax (214) 242-3155 or call toll free (888) 839-4830 or send e-mail request @ [email protected]. Please include your company name and the specific fax numbers(s) at which you do not wish to receive faxes from us. Our failure to comply with your request may be unlawful. _______________________________________________ Sprinklernotes mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklernotes
