American Fire Sprinkler Association 12750 Merit Dr., Suite 350 * Dallas TX 75251 Ph: (214) 349-5965 Fax: (214) 276-0908
----------------- TECHNICAL UPDATE MARCH 12, 2010 ----------------- I am installing a residential system in a home that has a basement that is being sprinklered with a wet pipe system. From this system, I am installing an antifreeze loop for the upper portion of the home. My sprinkler riser has a reduced pressure backflow preventer (RPZ) at the point of connection to the fire line. The riser piping would go vertical from the RPZ device feeding the wet pipe sprinkler system to the antifreeze loop subsystem. Am I required to install an additional RPZ as shown Figure 8.3.3.3.2.1? If not, is an expansion chamber required at the RPZ on the system riser?” We have reviewed NFPA 13D, 2010 Edition as the applicable standard. Our informal interpretation is that if a RPZ is on the system riser, the antifreeze loop can be connected in accordance with Figure 8.3.3.3.1.1. NFPA 13D considers Figure 8.3.3.3.1.1 and Figure 8.3.3.3.2.1 equally acceptable and does not dictate the requirement for a backflow preventer. It is the IBC and IPC that dictates protection against backflow and specifically states that if the system contains antifreeze that a RPZ type of backflow preventer shall be used. Since your system riser contains an RPZ, the IPC is satisfied so you can connect your antifreeze portion to the wet pipe sprinkler system using Figure 8.3.3.3.1.1 (the old drop loop and check valve with a hole). This isolates the antifreeze solution while allowing the build-up in pressure form temperature changes to vent ck into the wet pipe system. The requirement for an expansion chamber is literally a requirement just for antifreeze systems connected to a wet-pipe system. The expectation is that these systems are small and there is not enough trapped air to cushion the thermal expansion. There is no requirement in NFPA 13D (or NFPA 13) for an expansion chamber to be installed on a wet pipe system that utilizes a backflow preventer. ----------------- 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
