You could represent the tank as a public supply with a static pressure equal to the height of the water in the tank (problem is do you use full, half, or empty elevation). The residual pressure would be the at the pump suction when you are flowing 1500 gpm. I know it would look pretty weird showing Static: 10 psi, Residual: -45 psi, Flow: 1500 gpm @ pump suction, but this is your reality with the 1000 ft of 6" suction piping. Why would you even send anything to an AHJ when you know the situation is not possible? (rhetorical question)
I forgot, maybe the minimum suction pressure can't go below -14.7 so this would mean considerably less flow than 1500. Where are the academics when we need some hydraulic theory? Bill Brooks William N. Brooks, P.E. Brooks Fire Protection Engineering Inc. 372 Wilett Drive Severna Park, MD 21146-1904 410-544-3620 410-544-3032 FAX 412-400-6528 Cell -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Ralphy Henderson Sent: Tuesday, June 07, 2011 1:00 PM To: [email protected] Subject: RE: Pump, Tank, 1000 ft suction line..... No, I don't need a PC to do the calc but I'd like for hydra calc to show all this w/o an additional set. Things like that tend to confuse the AHJ's - especially hand written things. You would think a multi thousand dollar program would be able to take the calc from a tank to the pump and to the system in one report - but it looks like that's not the case. --- On Tue, 6/7/11, George Church <[email protected]> wrote: From: George Church <[email protected]> Subject: RE: Pump, Tank, 1000 ft suction line..... To: "[email protected]" <[email protected]> Date: Tuesday, June 7, 2011, 4:47 PM Why not take a piece of paper, write down the length of the run, multiply it by the FL/ft, and use a calculator to multiply the two and get the friction loss? Then correct for any dif in elevation by multiplying the dif x .433. It really isn't that hard and you really don't need a pc to run a simple supply calc. Ok, maybe I should say you SHOULDn'T need a pc.... George L. Church, Jr., CET Rowe Sprinkler Systems, Inc. PO Box 407, Middleburg, PA 17842 877-324-ROWE 570-837-6335 fax [email protected] -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Ralphy Henderson Sent: Tuesday, June 07, 2011 12:29 PM To: [email protected]; [email protected] Subject: RE: Pump, Tank, 1000 ft suction line..... Bob, That's kind of what I was getting at. I'll probably just have to submit a separate calc showing the 150% pump rating through the pump to the tank to prove the losses are acceptable. Does anyone know if there is a way to do this in a single calc in hydracalc? I can put in an additional water 'source' but then would have to enter in a static, res, and flow for the tank to get it to run through the program and these numbers are unknown (except for static). Thanks, RB --- On Mon, 6/6/11, Bob <[email protected]> wrote: From: Bob <[email protected]> Subject: RE: Pump, Tank, 1000 ft suction line..... To: [email protected] Date: Monday, June 6, 2011, 11:05 PM Ralph, Looking at this I'm coming up with 20.3 psi loss in 1000' of pipe not counting fittings and valves. (4.52*1000.00^1.85)/(140^1.85*6.4^4.85) = .0203 .0203 * 1000 = 20.3. 6.4" is ID of 6" Tyton Joint Pipe DI. Fittings and valves will increase your losses. At 1500 gpm you will have .43 psi / ft loss. These numbers will vary depending on pipe type and ID. As far as how to do it; I think I would simply run the numbers through the calculation back to the tank. Or better yet, if there are hydrants fed off of the tank have a flow test performed and calc back to that point of connection. Bob Knight, CET III 208-318-3057 www.firebyknight.com -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Vince Sabolik Sent: Monday, June 06, 2011 4:37 PM To: [email protected]; [email protected] Subject: Re: Pump, Tank, 1000 ft suction line..... Ralph - My rough calcs say about 16 psi loss at 100% flow and 34 psi loss at 150% flow. Unless this is an elevated tank, or your source is uphill from the pump, this won't work. At 06:32 PM 6/6/2011, you wrote: >at 1000 gpm, you are going to lose about 2 psi per 100' of 6" >ductile iron pipe. At 1500 gpm, you are going to lose about 5 psi / >100' of DI pipe. You need to have enough elevation between the tank >and pump to provide a positive pressure at the suction flange. > >On 6/6/2011 3:28 PM, Ralphy Henderson wrote: >>Hi All, >> >>Can someone explain to me how one would go about calculating a fire >>pump being fed solely from a water storage tank but with a 6" x >>1,000 ft suction line? I've calculated fire pumps off of tanks that >>had a small 10 ft. suction lines directly off the tank but never one >>with this amount of underground line and I'm concerned about making >>sure friction losses in the suction are properly accounted for. The >>pump is 75 psi @ 1000 gpm. >> >>We use hydracalc, and typically when a fire pump and tank scenario >>comes up we have only one 'source', the pump, being specified. >>Would this change in this instance? I guess the main thing I'm >>concerned about is coming up with a negative pressure at the suction >>flange due to such a long run. >> >>Any help? >> >>-RB >> >>_______________________________________________ >>Sprinklerforum mailing list >>[email protected] >>http://fireball.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 >[email protected] >http://fireball.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) > >__________ Information from ESET NOD32 Antivirus, version of virus >signature database 6185 (20110606) __________ > >The message was checked by ESET NOD32 Antivirus. > >http://www.eset.com > > Vince Sabolik Christi Fire Protection, Inc. 11351 Pearl Road Strongsville, Ohio 44136 T 440 572-7730 F 440 572-7719 Email: <mailto:[email protected]>[email protected] _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.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 [email protected] http://fireball.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 [email protected] http://fireball.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 [email protected] http://fireball.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 [email protected] http://fireball.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 [email protected] http://fireball.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)
