You're certainly not the only one who needs that self reassurance, I know two other people like that. ;-)
Mark at Aero 602 820-7894 Sent from my iPhone > On Mar 15, 2016, at 9:59 AM, "Steve Leyton" <[email protected]> > wrote: > > I have to say that my FAVORITE emails are the ones that contain the phrase, > "Steve is correct." I never get tired of reading that ... > > SML > > -----Original Message----- > From: Sprinklerforum [mailto:[email protected]] > On Behalf Of Tony Eggster > Sent: Tuesday, March 15, 2016 8:01 AM > To: [email protected] > Subject: Re: Standpipe Calc: Adding City Demand to Pumper Truck? > > All that confirms my suspicions. I always calc to the FDC but when I came > across these plans I tried to find justification in '14 and saw the material > in the annex which set off a lot more questions. > > > Good to know guys, > thanks! > > >> On Mon, Mar 14, 2016 at 4:13 PM, Tom Duross <[email protected]> wrote: >> >> Steve is correct. A simple 151@0 to 150@1000 (or 1250) supply line, >> regardless of city supply flow unless of course you can't supply the >> pumper with 1000 or 1250 gpm supply. The reason for the 150 psi >> demand pressure is the system is hydro'd to 200. You can use the two >> (2) uppermost FDV's on the HMD standpipe flowing 250 each for the >> standpipe required flow of 500 and then the uppermost FDV on each >> remaining standpipe at 250 each to a max of 1000 for a sprinklered >> building or 1250 for partially or a non-sprinklered building. All >> flows must have a minimum residual of 100 psi but I do what Steve says >> and shoot for 105. You can use K factors of 25 and >> 50 at the minimum residual of 105 to make your standpipe calc's easier >> and the FDC is the supply point. Remember not to calc a hole in the >> pipe but to include the tee, nipple and valve. >> TD >> >> >> Tony: >> >> You (or the submitter) are over-simplifying what the annex says. It's >> not the intent that you take the city flow test and add it to the pumper >> curve. >> NFPA 1901 sets the basic performance curve for a pumper at 150 PSI/1,000 >> GPM. NFPA 13E is the standard for FD Operations for buildings equipped >> with sprinklers and standpipes - that standard goes into the company >> engineer's procedure for calculating the discharge pressure of the pump >> based on suction pressure, friction loss in hose and other variables. But >> the bottom line is that it's all targeted at discharging 150 PSI >> residual at >> 1,000 GPM. This has NOTHING to do with pressure at the FDC; it has to do >> with calculating the performance of the apparatus. What gets to the FDC >> is >> up to the engineer. >> >> Which is why 7.7.4 states, "When the system demand to be supplied by >> the fire department at the fire department connection is being >> determined, the local fire department shall be consulted regarding the water >> supply >> available from a fire department pumper." FROM A FIRE DEPARTMENT PUMPER. >> It's up to the incident commander and his or her engineer to determine >> the suction pressure and set their discharge to whatever is required >> to make their programmed starting pressure. And based on the >> nationwide standard and best practices, that is almost certain to be >> 150 PSI at the prescribed flow rate. The engineer will calculate the >> friction loss in the discharge hose that's connected to the building. >> If you are reviewing plans that show >> 150 PSI residual plus a positive suction head at that flow rate as the >> inlet pressure, then that is almost certainly not correct. >> >> To answer your question, if I have a building with two (750 GPM) or >> three or more (1,000 GPM) standpipes, we plug in a "flow test" static >> pressure of >> 151 >> PSI and a residual of 150 PSI at the target flow rate and we run the calc' >> using the FDC as the "city connection". We plug in a 500 PSI hose stream >> allowance at the most remote standpipe outlets and at 250 GPM hose >> streams at those points in the bulk main system where the other risers take >> off. >> We >> allow 5 PSI for loss in a standard hose valve so the minimum pressure >> at any node is 105 PSI. >> >> The foregoing is my opinion only and does not represent the opinion of >> or any manner of interpretation by NFPA or the Technical Committee on >> Standpipes. >> >> Steve Leyton >> >> >> Quick question: I'm reviewing some plans for a manual class I >> standpipe and the designer added the city flow test to the usual >> 1000gpm fire pumper curve in order to keep all the pipe down to 4". I >> see in the NFPA 14 appendix that you can do this but personally I've >> always just calculated solely to the pumper curve. How do you guys do >> it? >> >> Also, I'm assuming that if you do factor in city supply wouldn't that >> frequently require high pressure pipe and fittings depending on city >> supply psi? >> >> _TONY >> >> >> _______________________________________________ >> Sprinklerforum mailing list >> [email protected] >> >> http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkl >> er.org > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
