American Fire Sprinkler Association 12750 Merit Dr., Suite 350 * Dallas TX 75251 Ph:(214) 349-5965 Fax:(214) 276-0908
-------------------------------- TECHNICAL UPDATE DECEMBER 10, 2009 -------------------------------- “We perform a functional flow test at the finals for all residential sprinkler systems. When we did the flow test we made the gallons per minute, but the pressures were 5 psi or less (gauges were not calibrated very low). I indicated to the contractor that we needed the operating pressures at the two heads to flow in accordance with the technical data sheet, e.g. Reliable Model RFC 43 Concealed on a 16 X 16 spacing, 13 gpm at 9.1 psi. He indicated that the pressures are irrelevant because the gallons were met. We explained that proper head discharge patterns would not be achieved if the required pressures were not meet. He further challenged. The contractor stated that he further investigated and installed a pressure gauge up stream on the head before the two remote heads (closer to the riser) and it had 10 psi, but only 5 psi at the head, we stated that would not be acceptable because the pressure at the remote heads need to be obtained. Can the pressure at the sprinkler be measured?” We have reviewed NFPA 13D, 2007 Edition that you indicated as the applicable standard. Our informal interpretation is that attempting to field measure the pressures at the sprinkler may indicate inaccurate pressures. Nowhere in the standard is acceptance testing mentioned other than checking the piping for leaks at the system working pressure or if an FDC is present, a standard hydrostatic test. Hydraulic calculations are performed to determine the minimum necessary flow and pressure needed on the system all the way to the city main. These formulas and procedures are themselves based on tests, verified by NFPA, SFPE, FMRC, UL and every single sprinkler manufacturer. The whole purpose of NFPA 13D requiring hydraulic calculations is to provide a scientific, reproducible and cost-effective means of determining the necessary water flow and pressure. A sprinkler flow test may not accurately measure pressure, is not reproducible, and is labor intensive. However, there have been cases where the fire marshal is suspicious of these calculations and wants a flow test performed. The focus should be instead to diligently verify the calculations and that the installed piping and components matches that used in the calculation, ensure the reading for the city water supply is accurate, and determine if the supply is greater than the demand as indicated by NFPA 13. ---------------- 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 Linda Dawson 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
