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.
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