Craig, the 10X does apply, but does the 10X apply to the 6” of the backflow preventer or the 4” of the suction pipe? Todd G Williams, PE Fire Protection Design/Consulting Stonington, CT 860-535-2080 (tel:860-535-2080) (ofc) 860-554-7054 (tel:860-554-7054) (fax) 860-608-4559 (tel:860-608-4559) (cell)
> > On Oct 9, 2023 at 9:02 AM, <Craig Prahl (mailto:[email protected])> > wrote: > > > > > > 4.29.3 Devices in Suction Piping. Where located in the suction pipe of > the pump, check valves and backflow prevention devices or assemblies shall be > located a minimum of 10 pipe diameters from the pump suction flange. > > > > > > > > Per the wording in NFPA 20, I’d have to say yes, the 10X rule applies. > > > > > > > > It all comes back to laminar versus turbulent flow. The check valves can > create turbulence. The water flow needs time to “smooth out” before > hitting the pump. > > > > > > > > > > > > > Craig Prahl |Jacobs | Fire Protection SME – Special Hazards | > [email protected] (mailto:[email protected])|www.jacobs.com > (https://urldefense.com/v3/__http:/www.jacobs.com/__;!!KZTdOCjhgt4hgw!-_khxU8gU0_6jc895I7kRbnU8JghRDsWgqOblZ4jr7Qp2IVbR30VYw_hWvNFtphnl0uWpB9KIvbYi1pvZz4$) > > > > 1041 East Butler Road Greenville, South Carolina 29606 > > > > CONTACT BY: Phone 1-864-676-5252, Email or MS TEAMS > > > > > > > > > > > > > > > From: Fpdcdesign <[email protected]> > Sent: Saturday, October 7, 2023 10:16 AM > To: Discussion list on issues relating to automatic fire sprinklers > <[email protected]> > Subject: [EXTERNAL] [Sprinklerforum] Distance to fire pump suction > > > > > > > > > > > I have a system with a 6” backflow preventer, which reduces to 4” immediately > after. There is approximately 48” of 4” pipe to the suction flange on a 4 x 3 > pump. All elbows are turning correctly. Is this sufficient? Does the 10x rule > apply to the size of the backflow preventer or the fitting directly attaching > to the pump? > > > > > > > > > > > Todd G Williams, PE > > > > > Fire Protection Design/Consulting > > > > > > Stonington, CT > > > > > > 860-535-2080 (tel:860-535-2080) (ofc) > > > > > > 860-554-7054 (tel:860-554-7054) (fax) > > > > > > 860-608-4559 (tel:860-608-4559) (cell) > > > > > > > > NOTICE - This communication may contain confidential and privileged > information that is for the sole use of the intended recipient. Any viewing, > copying or distribution of, or reliance on this message by unintended > recipients is strictly prohibited. If you have received this message in > error, please notify us immediately by replying to the message and deleting > it from your computer. > _________________________________________________________ SprinklerForum > mailing list: > https://lists.firesprinkler.org/list/sprinklerforum.lists.firesprinkler.org > To unsubscribe send an email to [email protected] >
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