A point that has been made indirectly but worth repeating is that these are TWO SEPARATE and UNRELATED CALCULATIONS.
One - fire flow - it normally made by the Civil engineer, or maybe on rare occasions a fire protection engineer. The procedure typically follows that outlined in Appendix B of the IFC, or a similar method depending on jurisdiction. If the engineer is on the ball, they will verify sprinkler calculation flows (inside sprinklers and hose allowances) to confirm their pipe sizes work for both calculations. Usually on a commercial job, the fire flows are greater than the sprinkler demands and will drive the sizing of the underground at the site. Not always the case on an industrial or warehouse site. The other calc - the sprinkler system calc - is just that. The demand of the sprinkler system inside the building plus hose allowances. If the site engineer is doing their job well, they'd ask the professional in charge of fire protection, be it the design build contractor or the design team P.E. getting paid to spec the fire protection, for recommended pipe sizing for the underground supply into the building. THIS pipe sizing depends entirely on the sprinkler calcs. The problem of course is that too often the engineer specifying the fire protection couldn't explain what a hose allowance is, let alone the difference between it and the site fire flow. So they throw an note on the plans to get the sizing from the low-bid sprinkler contractor; or worse, they just guess at lead-in sizes (6 inch seems to work most of the time - except for when it doesn't). On a side note, if you want to have fun, ask a Civil engineer about the special testing requirements for underground fire mains. Many have no clue they need to do any more than pressure test to 50 psi over static and flush just enough to get the chlorine out. Mark A. Sornsin, P.E. | Karges-Faulconbridge, Inc. | Fire Protection Engineer | Fargo, ND | direct: 701.552.9905 | mobile: 701.371.5759 | http://www.kfiengineers.com -----Original Message----- From: Sprinklerforum [mailto:[email protected]] On Behalf Of Brian Harris Sent: Tuesday, December 22, 2015 2:13 PM To: [email protected] Subject: RE: Fire Flow vs Hydraulic calc's Peter- Much appreciated. Brian Harris, CET BVS Systems Inc. bvssytemsinc.com ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please visit http://www.symanteccloud.com ______________________________________________________________________ _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
