FPE Corner Continued from page 22
pumps are limited to a maximum individual size of 2,500 gpm at 125 psi. Similar to NFPA 409, one redundant fire pump must be provided, i.e., the system must be capable of meeting the largest water demand with the largest fire pump out of service. Fire pumps are to be electrically dri- ven when supplied by a reliable electrical power supply source; otherwise, diesel engine driven pumps are to be used. It is noted that pumps must be automatically started from a pressure drop in the system. NFPA 409 also rec- ommends that fire pumps be arranged to start via an elec- trical start signal from the fire suppression control panel. Surge suppressor (expansion) tanks are also required
for each sprinkler riser, for the high-expansion foam sys- tem riser and at the discharge of the fire pump system. In my next article I will discuss the specific fire sup-
High-expansion foam generator.
02-15 permits use of air within the hazard. This allows the designer to avoid designing costly outside air supplies to the generators. Foam generators may be either electrically powered or water powered. The high expansion foam system will have its own fire suppression control panel. The activation of foam system discharge is initiated by a sprinkler system water flow alarm switch, manual release stations, and, where preac- tion sprinkler systems are used, the heat detection system. Separate notification appliances are required to activate upon the foam system discharge and must be blue visual alarm devices, either stroboscopic or rotating beacons. ETL 02-15 has a fire suppression system matrix of opera- tion that captures all the functions of the suppression sys- tem controls.
pression system design features of a recent project using high-expansion foam. n
engineer and mechanical engineer with bachelor’s and master’s degrees from the University of Maryland Department of Fire Protection Engineering. He is past president and a Fellow of the Society of Fire Protection Engineers. He is president of S. S. Dannaway Associates, Inc., a 15-person fire protection engineering firm with offices in Honolulu and Guam. He can be reached via email at
SDannaway@ssdafire.com.
Samuel S. Dannaway, PE, is a registered fire protection FPE Corner Letters
Mr. Dannaway, I just wanted to take a minute to thank you for your
writings in the FPE Corner. I have found your articles very informative and helpful. I especially enjoyed last months article (April 2011), “Is bigger better.” As an AHJ, I agree that keeping the designer and AHJ on the same sheet of music is one of, if not the most impor- tant factor during a project’s life. It has been my experience that open lines of com- munication between the designer and myself have not only aided in the successful and timely completion of projects, but both sides usually take something away from the process that will assist them in the future. Heck, as you point to in your article, even the most sea- soned of veterans get stumped. Lord knows the num- ber of changes from the 93 version, which I learned from while attending Oklahoma State, have been enough to keep me from feeling overconfident. Anyway, I look forward to future articles, and
Wet pipe sprinkler risers and hi-ex foam. Normally, municipal or military base water supply sys-
tems are not capable of meeting the total demand of the hangar fire suppression system and an onsite storage/fire pump system is required. Two equal size water tanks are required, sized to support 120 percent of the maximum demand, for a period of 30 minutes. The purpose of two tanks is to permit the fire protection system to be opera- tional with one tank out of service for maintenance. Fire
Page 24/Plumbing Engineer thanks again.
Respectfully, Captain Scott Burke #1380, CFEI Fire Prevention — FBFD Farmers Branch, TX 75234
The views and opinions expressed in this column are those of the author and do not reflect those of Plumbing Engineer nor its publisher, TMB Publishing.
May 2011
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