You use the residual pressure with the full demand. However, through the nipple and tee to the valve you only flow 250 gpm.
Travis Mack, SET M.E.P.CAD | 181 N. Arroyo Grande Blvd. #105 I Henderson, NV 89074 www.mepcad.com<http://www.mepcad.com/> | m: 480.547.9348 AutoSPRINK | AutoSPRINK FAB | AutoSPRINK RVT | AlarmCAD Book appointment time in my calendar https://calendly.com/t_mack_mepcad ________________________________ From: Greg McGahan <[email protected]> Sent: Tuesday, October 31, 2023 4:20:27 AM To: Discussion list on issues relating to automatic fire sprinklers <[email protected]> Subject: [Sprinklerforum] Re: Pressure Regulating Valves Residual Pressures Micah, When you test the valves you will test each one individually flowing 250 gpm so therefore you have to size them individually. On Tue, Oct 31, 2023 at 5:53 AM Micah Davis <[email protected]<mailto:[email protected]>> wrote: Good morning, Forum! I hope everyone is having a great week!! I think I got this right, but someone is questioning me. I have an automatic standpipe with factory pressure-regulating valves (i.e., Zurn 4000). When calculating residual pressures at the inlet of the PRV to be used in the sizing charts, the question is, how much water should I be flowing in the system? One suggestion is only flowing 250 gpm at the hose valve you are sizing. The other suggestion is flowing the system demand flow per NFPA 14. In this case, that would be 750 gpm (250 gpm at each of the two most remote hose valves plus 250 gpm at the top of the only other standpipe). We are in agreement that the calculation should be a source calc to determine the actual pressure provided by the system. Thank you, Micah Davis Ferguson Fire Design _________________________________________________________ SprinklerForum mailing list: https://lists.firesprinkler.org/list/sprinklerforum.lists.firesprinkler.org To unsubscribe send an email to [email protected]<mailto:[email protected]> -- Greg McGahan Genesis Fire Services, LLC 4912 Glover Lane. Milton, FL 32570 P- 850-637-8535 C- 850-712-9555
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