Greg, Q=AV is the basic formula, where A= area and V=velocity. Corrected to use ft/sec and square inches, it would be 3.11688 x V x A. Velocity is going to be the hard one to figure. I don't recall from my hydraulics classes (a long time ago as well) about any formula for open ended pipe. Using the empirical K factor calculation that Craig described would probably be the closest to using the sprinkler model. I did figure K factor calculations for my hose monster and nozzles from the charts and it does hold across the full range, so that might be fairly accurate.
However, the pressure at the top will be 0 and will increase due to elevation gain as well as decrease due to friction loss. Using the static pressure at the base will not be accurate for calculating flow because once you start flowing, the pressure will decrease due to the friction loss. In addition, the total elevation will decrease once you start flowing water, although that may be negligible for short periods of time due to tank diameter. I am assuming you are looking for the equilibrium point. The best way to figure this would be through computer modeling. I'm not sure if Autosprink can handle this, but it very possibly could. At 09:36 AM 8/6/2009, Greg McGahan wrote: >Guys, I know all of the basic hydraulic stuff....I do NOT know the K >factor of an 8" open pipe and don't feel comfortable guessing at >formulas. I went to college and I know there is a formula that will >easily tell you a reasonable expected flow and pressure. Bu that was >a long time ago. > >Greg McGahan >Operations Manager > >Living Water Fire Protection >1160 McKenzie Road >P.O. Box 877 >Cantonment, Florida 32533 >(850) 937.1850 | Fax (850) 937.1852 | Cell (850) 554.3231 >[email protected] > > > >-----Original Message----- >From: [email protected] >[mailto:[email protected]] On Behalf Of >[email protected] >Sent: Thursday, August 06, 2009 8:29 AM >To: AFSA >Subject: Re: water storage tank > >That depends on flow rate Greg. Higher flow = higher loss per >ft. Longer run = higher loss at specified flow rate. > > > > >Sent from my Verizon Wireless BlackBerry > >-----Original Message----- >From: "Greg McGahan" <[email protected]> > >Date: Thu, 6 Aug 2009 08:06:45 >To: <[email protected]> >Subject: RE: water storage tank > > >I know the static pressure. I need the RESIDUAL pressure and flow >through an open 8" pipe at ground level. > >Greg McGahan >Operations Manager > >Living Water Fire Protection >1160 McKenzie Road >P.O. Box 877 >Cantonment, Florida 32533 >(850) 937.1850 | Fax (850) 937.1852 | Cell (850) 554.3231 >[email protected] > > > >-----Original Message----- >From: [email protected] >[mailto:[email protected]] On Behalf Of >[email protected] >Sent: Thursday, August 06, 2009 7:28 AM >To: [email protected] >Subject: RE: water storage tank > >The formula is: ft of water x .433 = psi > >So for 140 ft of head the approximate psi would be around 60 psi, at >70 ft it would be approximately 30, etc. > >Note that this does not account for the loss through the tank >outlet, vortex plate valves or piping loss. > >Find out what that 8" is. Especially if it's a plastic. Beware of HDPE. > > >Craig L. Prahl, CET >Fire Protection Specialist >Mechanical Department >CH2MHILL >Lockwood Greene >1500 International Drive >PO Box 491, Spartanburg, SC 29304-0491 >Direct - 864.599.4102 >Fax - 864.599.8439 >[email protected] >http://www.ch2m.com > > >-----Original Message----- >From: [email protected] >[mailto:[email protected]] On Behalf Of Greg McGahan >Sent: Thursday, August 06, 2009 8:18 AM >To: [email protected] >Subject: water storage tank > >We have a situation where a new water storage tank is being >installed on a public utility system and I need some help if anyone >can tell me the following: > >New Tank - 140' high > >8" pipe (unknown type) going straight to ground level > >What is a reasonable expected flow and residual pressure? > >Any help would be appreciated. > >Greg McGahan >Operations Manager > >Living Water Fire Protection >1160 McKenzie Road >P.O. Box 877 >Cantonment, Florida 32533 >(850) 937.1850 | Fax (850) 937.1852 | Cell (850) 554.3231 >[email protected] > > >_______________________________________________ >Sprinklerforum mailing list >http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum >For Technical Assistance, send an email to: [email protected] > >To Unsubscribe, send an email to:[email protected] >(Put the word unsubscribe in the subject field) >_______________________________________________ >Sprinklerforum mailing list >http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum >For Technical Assistance, send an email to: [email protected] > >To Unsubscribe, send an email to:[email protected] >(Put the word unsubscribe in the subject field) >_______________________________________________ >Sprinklerforum mailing list >http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum >For Technical Assistance, send an email to: [email protected] > >To Unsubscribe, send an email to:[email protected] >(Put the word unsubscribe in the subject field) >_______________________________________________ >Sprinklerforum mailing list >http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum >For Technical Assistance, send an email to: [email protected] > >To Unsubscribe, send an email to:[email protected] >(Put the word unsubscribe in the subject field) >_______________________________________________ >Sprinklerforum mailing list >http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum >For Technical Assistance, send an email to: [email protected] > >To Unsubscribe, send an email to:[email protected] >(Put the word unsubscribe in the subject field) Todd G. Williams, PE Fire Protection Design/Consulting Stonington, Connecticut www.fpdc.com 860.535.2080 _______________________________________________ Sprinklerforum mailing list http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
