You are correct....the answer I got was "we don't know"........from the horse's 
mouth. Thanks for all of your help, I will let you know how it works out in a 
few hours.

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 | CellĀ (850) 554.3231
[email protected]



-----Original Message-----
From: [email protected] 
[mailto:[email protected]] On Behalf Of Todd Williams
Sent: Thursday, August 06, 2009 11:04 AM
To: [email protected]
Subject: RE: water storage tank

Someone designed a water tank and they can't tell you the output? Who 
sold that design contract?


At 11:18 AM 8/6/2009, you wrote:
>I am getting info piecemeal from the engineering firm that is in 
>charge of the tower. They say they don't
>Know what the residual pressure and flow will be when the tower is 
>completed. We have a sprinkler system going in "next door" to the 
>tower using the existing water from the old system. However, they 
>have installed a 4" pipe with a hydrant instead of 6" (many years 
>ago)and nobody knew until we dug it up.
>
>Now we are flowing 600 gpm through a 4" pipe to our source and the 
>calcs are too close for comfort. We are looking for a "guesstimate" 
>of the available water at the base of the tower without any fittings 
>or valves. I can add them in the 8" line from the base to the new 
>tie in point where the systems tie together. We are talking about 
>needing to pick up 5 to 10 psi  not 20 or 30, so as long as we are 
>close we should be good.
>
>This really should fall on the EOR, but as is often the case in this 
>region, if we want to finish the job on time, we have to get an 
>answer immediately.
>
>So I can say that I should reasonably be able to expect .156 x 140' 
>= 22 lbs of loss from the tank to the bottom w/o 
>fittings....therefore if we say we should reasonably expect 1,500 
>gpm at 35 psi?
>
>
>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 9:28 AM
>To: [email protected]
>Subject: RE: water storage tank
>
>You're asking an open ended question.  Sorry for running you around 
>in circles.
>
>There are too many unknown variables here that are needed to make 
>any kind of determination.
>
>Like has been said, how much pipe, fittings, valves, elevations, 
>what kind of discharge gpm, etc. etc, etc.
>
>Plus the value at what tank level, since the tank head will affect 
>the residual pressure.
>
>If you go by the flow required to produce a 10 fps velocity out of 
>NFPA 24 for instance, that flow rate for an 8" would be 1560 gpm.
>
>If you use cement lined DI pipe at 1560 gpm the pressure drop is 
>.156 psi/10ft.
>
>Ina real simplistic format, if you had 20 ft of pipe, static of 70 
>psi, flowing 1560 gpm, the line loss equals .313 psi.  Use 1560 gpm 
>and 69.6 psi for the K-factor which comes out to 
>K=197.8.   Naturally the gpm will be slightly less than at the 
>discharge but that difference would be negligible at these variables.
>
>This is all nominal since like I said the value will vary depending 
>on tank level and other unknowns.
>
>
>
>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 9:37 AM
>To: [email protected]
>Subject: RE: water storage tank
>
>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]
>
>
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Todd G. Williams, PE
Fire Protection Design/Consulting
Stonington, Connecticut
www.fpdc.com
860.535.2080  
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