True about the full tank but a full tank is the max. pressure you'll have at the beginning of the fire so as the fire progresses and probably starts opening more sprinklers the water level is falling along with your pressure. For that reason if one sizes the system piping to the full tank with a small safety factor then the system is below design as the fire burns. Just the way I look at it, though
Russell Rewis Brown Automatic Sprinklers, Inc. 107C Hemlock Street Valdosta, Georgia 31601 229-244-8130 [EMAIL PROTECTED] -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Mark Sornsin Sent: Saturday, August 02, 2008 11:56 PM To: '[email protected]' Subject: RE: effective tank volume Yes - but remember that you have positive pressure when the tank is filled. (Normally, a horizontal, split-case pump is taking suction from a tank whose water elevation - when filled - is above the centerline of the pump). It is only after the tank has nearly emptied that you'd have a negative pressure condition. At that point, you'll be in a siphon condition. Mark Sornsin, PE Ulteig engineers, Inc. Fargo, ND -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Russell Sent: Friday, August 01, 2008 3:57 PM To: [email protected] Subject: RE: effective tank volume Would not anything below the centerline of the pump impellor be a negative pressure? Split-case centrifugal pumps have to have a positive pressure on the suction side. Or have I misunderstood the situation? Russell Rewis Brown Automatic Sprinklers, Inc. 107C Hemlock Street Valdosta, Georgia 31601 229-244-8130 [EMAIL PROTECTED] -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Ed Kramer Sent: Friday, August 01, 2008 2:14 PM To: [email protected] Subject: RE: effective tank volume I recently completed a similar project. I agree with Mark, the available water is that part of the tank below the inlet of the overflow and above the bottom of the vortex plate. Also, reference NFPA 22 section 4.1.3 (03 edition). Ed Kramer Littleton, CO > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:sprinklerforum- > [EMAIL PROTECTED] On Behalf Of Todd Williams - FPDC > Sent: Friday, August 01, 2008 7:05 AM > To: [email protected] > Subject: effective tank volume > > I am working on a project where the water supply for the facility > will be fed from concrete tank(s). The absolute volume (completely > full) of the tank is 10098 gallons. A 6" suction line with elbow & > anti-vortex plate will need to be installed. According to NFPA 22, > the face of the suction elbow has to be a minimum of 6" above the > bottom of the tank. The take-out for the elbow is 8" and the top of > the pipe will be 4" (+/-) above that. I am trying to calculate the > effective or usable volume in the tank based on what my minimum > height above the floor can be relied on for suction. Would it be the > 6" to the bottom of the elbow? 14" to the center line of the suction > pipe? 18" to the top of the suction pipe? The tank is 10 feet tall, > so this could have a significant impact on available water. (BTW, I > am already assuming that the tank will only be filled 9" to 12" from > the top; would that be reasonable?) > > Todd G. Williams, PE > Fire Protection Design/Consulting > Stonington, Connecticut > www.fpdc.com > 860.535.2080 > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum > > To Unsubscribe, send an email to:Sprinklerforum- > [EMAIL PROTECTED] > (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) No virus found in this incoming message. Checked by AVG - http://www.avg.com Version: 8.0.138 / Virus Database: 270.5.10/1585 - Release Date: 8/1/2008 6:39 AM _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) No virus found in this incoming message. Checked by AVG - http://www.avg.com Version: 8.0.138 / Virus Database: 270.5.12/1589 - Release Date: 8/3/2008 1:00 PM _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
