65% of rated pressure at 150% of rated flow is the lowest pressure a pump can produce and qualify as a listed fire pump. Manufacturer’s regularly produce pumps with a flatter curve than that threshold. 78% is likely the pressure that particular pump and impeller produce at 150% flow. Get the factory test curve from the manufacturer by providing them with the pump serial number.
Regards, Mark Mark. R. Mannex, PE / MANNEX ENGINEERING / 425-331-9129 From: Steve Leyton <[email protected]> Sent: Wednesday, October 15, 2025 1:09 PM To: Discussion list on issues relating to automatic fire sprinklers <[email protected]> Subject: [Sprinklerforum] Re: Pump requirement at 150% flow Does anyone have the original factory bench test curve (or the OEM spec from the time of installation) for comparison? Steve From: Fpdcdesign <[email protected]<mailto:[email protected]>> Sent: Wednesday, October 15, 2025 12:50 PM To: Sprinklerforum <[email protected]<mailto:[email protected]>> Subject: [Sprinklerforum] Pump requirement at 150% flow I received and was asked to comment on a test report from a pump that failed. The pump is an electric 1000 gpm at 100 psi unit. One of the curious things on the report is that they are looking for 78% of rated pressure at 150% rated flow. NFPA 20 calls for 65%. Before I shoot my mouth off, is there any justification for this? 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)
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