Presuming the 1.5" lead in supports flow and pressure for the system at the system/main connection point AND the water availability data has a static pressure in a four inch or larger main that is above the demand point then the flow of two heads will not have an appreciable effect on the residual pressure. See Ed's post for made up numbers that illustrate the point. Four heads on the other hand suggest a 13R system which would require all the data (Ps, Pv,--I just like to have velocity pressure from the pitot so I can do my own calc, saved a fire pump requirement just a couple of weeks ago-- Pr and Q at Pr, pipe sizes, elevations and locations of all test hydrants and a grid map) gathered by doing water availability testing. On a 13D, two head calc there isn't a magic pressure that works for all systems. It's still the question of your demand being above or below the available residual pressure at the required operating flow with all heads in the design area flowing through the system as designed. The difference is that 40 or so gpm flowing in a four inch pipe isn't going to show much difference in residual pressure than the static. I hope that convoluted answer was helpful.
On 4/26/07, å... .... <[EMAIL PROTECTED]> wrote:
that 1.5 inch has to be the lead-in; will recheck it with the city. 4 heads at 20 gpm, even with overage is still under 100 gpm flow; you are right, so, now no need for a flow test. thanks-- 1.5" pipe TO the street or IN the street? _______________________________________________ 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)
-- Ron Greenman at home.... _______________________________________________ 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)
