How are the city pumps started, based on pressure drop? Consider the possibility that under a low flow condition of say 1-5 heads there may not be a significant pressure drop or flow large enough to start the city pumps. In that case I'd suggest use the non-boosted pressures and flow.
That would be your worst case. Now also depending on what kind of system you have say it's a LH system, you may still not have enough flow or pressure to start the city pumps even if you use the entire remote area plus hose stream. You might want to do two calcs depending on what you find out about the city pump's starting sequence because someone may want to know if the system would work based on worst case of no city pumps operating. Plug in 100 psi static and 110 psi residual and see if you calc program doesn't flag that as an irregularity. Craig L. Prahl, CET Fire Protection CH2MHILL Lockwood Greene 1500 International Drive Spartanburg, SC 29304-0491 Direct - 864.599.4102 Fax - 864.599.8439 CH2MHILL Extension 74102 [email protected] -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Brian Harris Sent: Tuesday, December 14, 2010 11:03 AM To: [email protected] Subject: Flow Test With City Pump Just did a flow test for a new project and the static was 100psi, opened the hydrant and the residual dropped to 50psi for a couple of seconds and then the city pumps kicked on and the residual went to 110psi. When doing the calc's for this system wouldn't you need to do it without the boost from the pumps? (S=100 R=50) If that is the case what do you do for the flow as the pitot reading was done after the pumps kicked in? Brian Harris First Defense Fire Protection 11957 Ramah Church Road Huntersville, NC 28078 Phone: 704.948.3506 Fax: 704.948.3507 Nicet # 128476 ======= Email scanned by PC Tools - No viruses or spyware found. (Email Guard: 7.0.0.21, Virus/Spyware Database: 6.16510) http://www.pctools.com/ ======= _______________________________________________ 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)
