Todd: If I understand the conditions correctly, the challenge is that you have three separate "systems" coming off the underground, which could literally be interpreted as requiring the min. flow and pressure as prescribed by 14. If it's one system, then it's a cumulative flow (1,000 GPM in this case), but this could be construed as 500 GPM x 3.
If you are calculating any one standpipe (based on this arrangement), I think the standard is clear that you should be proving 500 GPM at the required residual. If the pump can't generate adequate head for 100 PSI residual at the top, you can still prove the manual water supply from the FDC's. Since 4" is the minimum size anyway, the difference between a flow rate of 250 GPM vs. 500 GPM is pretty much moot, presuming the local FD can hit the building with at least 145-150 PSI. A word about the 3 separate feeds. I think most would agree that the installation of any valves or appurtenances that could fail or be left closed and that aren't absolutely essential to the operation of any sprinkler or standpipe system isn't a good idea. Why three standpipe "risers" when one would do? Why not one big combination system? You are right that "interconnected" isn't clearly defined in 14; the annex diagrams all focus on high-rise designs and show interconnection downstream of a fire pump. So your underground technically accomplishes that, albeit with the baggage of separate systems. Steve Leyton PROTECTION DESIGN & CONSULTING _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
