American Fire Sprinkler Association 12750 Merit Dr., Suite 350 * Dallas TX 75251
Ph:(214) 349-5965 Fax:(214) 276-0908 ----------------- TECHNICAL UPDATE APRIL 16, 2009 ----------------- "A legitimate stage has the proscenium opening protected by nozzles supplied by a deluge valve attached to a manual standpipe. The nozzles are 30 ft above the stage floor. The heat detectors are at the ceiling on the stage side. The engineer has specified 65 deg. pattern spray nozzles with 2.3 K-factor. NFPA 101 states that the curtain should be kept completely wet for 30 minutes. Does the demand from the deluge system need to be added to the sprinkler demand from the stage ceiling? How do you determine the water demand for the nozzles?" We have reviewed NFPA 13, 2007 Edition as the applicable standard. Our informal interpretation is that the demand from the deluge system should be added to the sprinkler system demand and the deluge design is based on 3 gpm per linear foot. The requirement for including demand for a water curtain in your calculations is found under Section 11.3.3.3. This section states, "If a single fire can be expected to operate sprinklers within the water curtain and within the design area of a hydraulically calculated system, the water supply to the water curtain shall be added to the water demand of the hydraulic calculations and shall be balanced to the calculated area demand." In addition, Section 11.3.3.1 establishes the delivery density the deluge system will have to deliver as 3 gpm per lineal foot with no sprinkler discharging less than 15 gpm. Regarding the nozzles that were specified, Section 8.15.16.2 indicates that the deluge system shall be provided with open sprinklers. An open sprinkler is different from a directional spray nozzle, so a question back to the specifying engineer is warranted. A directional spray nozzle will provide water in a specific, directional pattern according to NFPA 15 and is usually applied to a surface area such as vessels or transformers. NFPA 13 for stages addresses water curtains where the water discharges from open sprinklers and provides a curtain of water in front of the opening. Open sprinklers do not provide specific, directional discharge patterns onto a vertical surface. Note that the small K-factor of 2.3 will require a higher pressure to deliver the required 15 gpm for each sprinkler. ----------------- 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
