Thanks, Roland. I've seen both issues interpreted both ways. I took the time to peruse the AFSA's archive of informal interps concerning standpipes. One in particular (from 1996) gave good background info on why the last 100' can be 4". Apparently the 1990 edition of 14 explicitly stated it, but the wording was deleted in the 1996 edition in a rewrite. For anyone interested, search for 'standpipe' and then look for the result dated 10/13/1996.
Another of the informal interps stated a manual standpipe didn't need to be calced. I guess that's another indicator that section of 14 could use some clarification. In support of your interpretation (requiring the calc), the signage called for by sections 6.4.5.2.2 and 6.8 can't be done without multiple calcs. Ed Kramer Littleton, CO >On Aug 7, 2007, at 9:06 AM, Ed Kramer wrote: > >> Roland, your post reminds me about something that's confused me for >> many >> versions of 14. Section 7.8.2.1 gives guidance on how to pipe >> schedule a >> standpipe. Simple enough: look at table 7.8.2.1. OK, then it says >> ". . . >> to provide the required waterflow rate at the minimum residual >> pressure of >> 100 psi at the top-most 2 1/2" hose outlet . . ." What does that >> mean? Is >> it a pipe schedule or is it a hydraulic calc? It can't be both, >> can it? > >In a sprinkler pipe schedule there is a required flow and pressure >that you have to verify at the base of the riser (accounting for >elevation to the highest sprinkler). >For a standpipe, we have the required flow and pressure at the >highest outlet but nothing about a minimum inlet flow and pressure in >order to meet it with the defined pipe sizes. For that reason, I >have always read it to mean you still have to calc it. So why do a >pipe schedule? >> >> And another question: Table 7.8.2.1 has a heading titled "Total >> Distance of >> Piping from Farthest Outlet". This means the total footage of pipe >> from >> the underground stub-in to the physically most remote outlet, correct? > >I guess literally one could say ALL pipe throughout the system but >that would require one to ignore that we are looking at a flow path >(just like the alternate 13D calc method). Having just read your >example, I see you have a different question. I have always viewed >it as going in increments, just like 13 where the initial run from >the outlet would be 4 inches up to 100 ft in your example and then 6 >inch the rest of the way. Hydraulically it makes no sense to no do >the incremental approach. BAD wording combined with needing to do a >calc anyways causes me to always assign a size and leave it to the >calc to drive the final sizing and leave the schedule alone. > >Roland > >> >> So as an example, if I've got 3 Class I standpipes and the total >> footage of >> pipe (horizontal plus vertical) from stub-in to the remote 2 1/2" >> valve is >> 101', then the ENTIRE standpipe needs to be 6"? (flow to the most >> remote >> standpipe being 500 gpm, and flow in the common piping being 750 >> gpm and >> 1000 gpm). >> >> Ed Kramer >> Littleton, CO >> >> >> >>> Rich - do you really NOT require calculations on a manual even when >>> it is NOT a pipe schedule system? >>> >>> Roland >> >> >> >> _______________________________________________ >> Sprinklerforum mailing list >> [email protected] >> http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum >> >> To Unsubscribe, send an email to:Sprinklerforum- >> [EMAIL PROTECTED] >> (Put the word unsubscribe in the subject field) >> > >_______________________________________________ >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) _______________________________________________ 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)
