According to my cowboy physics, if there were no out flows in the municipal system, and you performed the flow test again, there would be a much higher flow rate and higher residual pressure.
DISCLAIMER. My physics degree is from the U of HK. Mark at Aero 602 820-7894 Sent from my iPhone > On Feb 22, 2015, at 10:37 AM, "Brad Casterline" <[email protected]> > wrote: > > Hello Mark! > > Thanks- it is an interesting problem and I have tried to figure it out up > one side and down the other. I think if everyone turned their water off > while I got a true Static it would be higher. And if they left it off while > I measured 265 GPM @ 8 PSI wouldn't the drop be greater (drop being the sum > of the velocity head and the friction head)? So you are right because under > those conditions I would state as being "fact" a storage tank that is higher > AND farther away than the first one :) (I think). > > I am now dwelling on Paul's original "... storage tank at 610 feet about the > POC...". I thought he must have meant above instead of about, and in Kansas > 610 feet above the POC means "upstream" of the POC because we don't even > have buildings that tall here. But names like Nor Cal and Morgan Hill got me > thinking it might really be above, and if so the new tank would make the > "static" 610x.433= 264 PSI at the POC, which would be an increase. > > thanks again man, > Brad > > -----Original Message----- > From: Sprinklerforum [mailto:[email protected]] > On Behalf Of [email protected] > Sent: Saturday, February 21, 2015 1:17 PM > To: [email protected] > Subject: Re: Hydraulic Calculations with two water sources > > Hi Brad and all, > I think you're missing the fact that the city water main serves many(maybe > thousands) of users between the possibly elevated tank and hydrant #2. The > static pressure you're reading at that hydrant is actually the residual > pressure remaining in the line after many thousand GPM is distributed to > users along the way. Without knowing all those flow points (hydraulic nodes) > it is impossible for you to calculate the information you are presenting as > fact. Aside from that, I agree that a meeting with the water purveyor is a > necessary step in the design. > > Mark at Aero > 602 820-7894 > > Sent from my iPhone > >>> On Feb 21, 2015, at 9:59 AM, "Brad Casterline" <[email protected]> >> wrote: >> >> Paul, >> >> I have been thinking more about this and re-reading the excellent > responses >> and learning. I think it is important to get an accurate sketch before you >> finalize the calculations. I would want to meet with the water department >> and draw the picture the numbers and your current understanding show for >> Hydrant #2: >> If the source for #2 is a storage tank its elevation would be 128/.433= > ~296 >> feet above the hydrant. It would also be about 10 miles away because > flowing >> 265 through 6" UG (minimum if serving hydrants) it would take about 60,000 >> feet of pipe and fittings to burn 120 PSI. This is not impossible but it > is >> strange that after all that the FD is left with 8 psi at 265 GPM to try to >> do something with, when 376 feet over and 50 feet down is hydrant #1 with > 40 >> @ 750! >> >> thanks and good luck, >> Brad >> >> -----Original Message----- >> From: Sprinklerforum > [mailto:[email protected]] >> On Behalf Of Brad Casterline >> Sent: Friday, February 20, 2015 10:02 AM >> To: [email protected] >> Subject: RE: Hydraulic Calculations with two water sources >> >> Thanks Paul. The first thing I noticed yesterday was that the static >> difference between #1 and #2 did not correspond to the elevation > difference. >> And 120 PSI worth of Pf+Pv from the source to the hydrant is 5-6 times > more >> than one would expect if it is serving hydrants. >> I can see 128,108,265. Is there any way something might have been jotted >> down wrong when the information was communicated? >> >> Brad >> >> -----Original Message----- >> From: Sprinklerforum > [mailto:[email protected]] >> On Behalf Of Paul Cetani >> Sent: Friday, February 20, 2015 9:12 AM >> To: [email protected] >> Subject: RE: Hydraulic Calculations with two water sources >> >> Hey Brad, >> This test was conducted by the water company and doesn't really sound > right >> to us either but, because of the water situation in California, they will >> not perform a new test. >> >> Paul B. Cetani >> Exec. Vice President >> >> Nor Cal Fire, Inc. >> 16840 Joleen Way, Bldg A >> Morgan Hill, CA 95037 >> T 408-776-1580 >> F 408-776-1590 >> [email protected] >> www.norcalfire.com >> >> CONFIDENTIALITY NOTICE: This message and any document accompanying it may >> contain confidential information >> belonging to the sender. The information is intended only for the use of >> individual or entity named above. If you are not the intended recipient, > or >> the employee or agent responsible to deliver this message to the intended >> recipient, you are hereby notified that any disclosure, copying or taking > of >> any action in reliance on the contents of this information is strictly >> prohibited. If you have received this transmission in error, please >> immediately notify us by telephone to arrange for return of the documents. >> >> >> -----Original Message----- >> From: Sprinklerforum > [mailto:[email protected]] >> On Behalf Of Brad Casterline >> Sent: Friday, February 20, 2015 6:08 AM >> To: [email protected] >> Subject: RE: Hydraulic Calculations with two water sources >> >> >> Paul, >> >> I am curious about the hydrant #2 flow test: >> >> "The closest hydrant from this water source (hydrant #2) is >> 50 feet higher in elevation than hydrant #1. Hydrant #2 has a static of >> 128psi, residual of 8psi, and a flow of 265gpm." >> >> If you have time will you post any additional details you know about it >> please? >> >> thanks, >> Brad >> >> _______________________________________________ >> 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 >> >> _______________________________________________ >> 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 _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
