American Fire Sprinkler Association 12750 Merit Dr., Suite 350 * Dallas TX 75251 Ph: (214) 349-5965 Fax: (214) 276-0908
----------------- TECHNICAL UPDATE June 1, 2010 ----------------- “We have a mechanical room of approximately 500 sq. ft. surrounded on all sides by light hazard rooms with 9 ft ceilings. The mechanical room is exposed to the structure with a roof slope of 3:12. The walls are not fire rated. The specified remote area size is 3,000 sq. ft. Will this need to be increased by 30 percent due to the mechanical room?” We have reviewed NFPA 13, 2010 Edition as the applicable standard. Our informal interpretation is that an additional increase should not be required. NFPA 13 does not discuss how to address a ceiling with a sloped area smaller than the size of the remote area. In order to identify the intent, we need to look at why the remote area is increased. In a nutshell, heat flows more quickly up the slope causing sprinklers away form the fire to activate. In order to ensure there is enough water with these additional sprinklers flowing, the standard imposes a 30 percent increase to the size of the remote area. As a side note, the additional sprinklers may not even be in the normal assigned rectangle for the remote area. Having more sprinklers assigned to the same branch line is more hydraulically demanding so it's immaterial. If the area of the sloped ceiling is smaller than the assigned remote area, in your case no more than 500 sq. ft. in a 3,000 sq. ft. remote area, the heat flow up the slope is bounded by construction so no additional sprinklers away from the fire will activate. As identified by other related issues, the construction has to be capable of stopping heat but does not have to be fire rated (see NFPA 13, Section 11.1.2(2)). These boundaries cannot be used as limiting the size of the remote area unless they are rated. ----------------- 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 © 2010, 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://fireball.firesprinkler.org/mailman/listinfo/sprinklernotes
