What is your site elevation AMSL? Have you tried to operate the pump yet? While we typically don't run pumps below 0 psi, it can be done by figuring in by also accounting for air pressure. While not recommended, as long as you are not cavitating the impeller, the system should work. I had a similar situation on an alternate water supply (seismic) ground level pool surface that was roughly 1' below the pump inlet. We discussed it with an engineer, and he said we could figure on approximately 14 psi of additional pressure (PSIA) acting on the surface of the pool. When we tested it, it worked without a hitch. Once you pass the opening spring pressure, BFP's typically drop in loss to a point. PSIA may give you enough pressure to make the system work. I've used this principal on subsequent projects where site conditions didn't allow for positive pressure on inlets. https://kimray.com/training/psia-vs-psig-whats-difference Jamie Seidl
On Wed, Aug 25, 2021 at 4:25 PM Joe Burtell via Sprinklerforum < [email protected]> wrote: > Yes, we have pottable water being taken from the same tanks. This is a > rural high school and this is their own water system that feeds the school. > So I need the backflow for that reason. > > Best regards, > > *Joe Burtell, SET, CFPS* > > [image: Burtell Fire_Small] > > Phone | Fax | Mobile| Text *406-204-4653 <++1-406-204-4653>* > > 116 N. 11th Street | Billings, MT 59101 > > Email: [email protected] > > Web Site: http://www.burtellfire.com > > *“**The bitterness of poor quality remains long after the sweetness of low > price is forgotten.**”* > > *NOTICE:* The information contained in this e-mail transmission is > intended only for use of the individual or entity named above. This e-mail > transmission, and any documents, files, previous e-mail transmissions or > other information attached to it, may contain confidential information that > is legally privileged. If you are not the intended recipient of this > e-mail transmission, or the employee or agent responsible for delivering it > to the intended recipient, you are hereby notified that any disclosure, > dissemination, distribution, copying or other use of this transmission or > any of the information contained in or attached to this e-mail is strictly > prohibited. If you have received this e-mail transmission in error, please > immediately notify us by return e-mail transmission and destroy the > original e-mail transmission as well as its attachments without reading or > saving it in any manner. Thank you. > > > On Wed, Aug 25, 2021 at 1:40 PM cliff--- via Sprinklerforum < > [email protected]> wrote: > > > Hi Joe, > > > > Why would you need the BFP if you have storage tanks? Are there other > > systems being fed from the same tanks that would necessitate the BFP? > > > > Cliff Whitfield, SET > > President > > > > Fire Design, Inc. > > 940 Summerbrooke Drive > > Tallahassee, FL 32312 > > Ph: 828-284-4772 > > > > > > > > [email protected] > > www.fire-design.com > > > > -----Original Message----- > > From: Sprinklerforum <[email protected]> On > > Behalf Of Joe Burtell via Sprinklerforum > > Sent: Wednesday, August 25, 2021 3:33 PM > > To: [email protected] > > Cc: Joe Burtell <[email protected]> > > Subject: Fire Pump Backflow > > > > I have a situation with a verticle in-line fire pump fed from water > > storage tanks. We have a double check backflow installed between the > tanks > > and the fire pump but we don't have enough pressure to open the backflow > on > > the upstream side between the tank and backflow. I talked with Watts > about > > it. They stated there are no backflows with weaker springs. I only have > > about 7 PSI out of the tanks. Has anyone ran into this situation before > and > > have any suggestions to resolve the issue? The engineer suggested piping > > the jockey pump before the backflow. Not sure how that would work in > theory. > > > > Best regards, > > > > *Joe Burtell, SET, CFPS* > > > > [image: Burtell Fire_Small] > > > > Phone | Fax | Mobile| Text *406-204-4653 <++1-406-204-4653>* > > > > 116 N. 11th Street | Billings, MT 59101 > > > > Email: [email protected] > > > > Web Site: http://www.burtellfire.com > > > > *“**The bitterness of poor quality remains long after the sweetness of > low > > price is forgotten.**”* > > > > *NOTICE:* The information contained in this e-mail transmission is > > intended only for use of the individual or entity named above. This > e-mail > > transmission, and any documents, files, previous e-mail transmissions or > > other information attached to it, may contain confidential information > that > > is legally privileged. If you are not the intended recipient of this > > e-mail transmission, or the employee or agent responsible for delivering > it > > to the intended recipient, you are hereby notified that any disclosure, > > dissemination, distribution, copying or other use of this transmission or > > any of the information contained in or attached to this e-mail is > strictly > > prohibited. If you have received this e-mail transmission in error, > please > > immediately notify us by return e-mail transmission and destroy the > > original e-mail transmission as well as its attachments without reading > or > > saving it in any manner. 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