The pressures you've noted came from the flow tester? If yes, the lower pressures you've noted are due to the higher volume you're flowing which is due to larger orifice. If you wanted to compare to the data plate, read the residual pressure on the supply side of the alarm valve and throttle the control valve to the correct GPM out of the tester, like you would with a pump test.
Sent from my iPhone On Jun 23, 2013, at 4:22 PM, "Douglas Hicks" <[email protected]> wrote: > We a forward flow at a church last week. When we did the main drain flow > test we got 30 PSI. We tested through a single snoot FDC, with the FDC > check valve turned around, the clapper valve was not removed. > #1 forward flow test with 1.5” nozzle. We got 24 PSI, 337 GPM > #2 forward flow test with 2” nozzle, 16 PSI and 493 GPM > # 3 forward flow test with 2.25” nozzle, 12 PSI and 536 GPM > The above results were with a straight fixed nozzle > > The hydraulic name plate > Design Density .10 GPM > Area of operation 917 Sq Ft (the sprinkler protects the basement, which > houses a day care, 2 bathrooms, janitor closet, mechanical room, elevator > room, and a hallway. > System demand at bottom of riser 242.8 GPM at 59.95 PSI > Water supply flow test, 84 PSI static, 70 PSI residual flowing 981 GPM > > > The water flow comes through the wall, 6 inches off the floor, makes a 90°, > up through the backflow device, through the 2.5 inch alarm check valve, 3 > more 90° to the single snoot FDC. Then through the wall and our flow tester. > The water was clean after 1 minute. We did not do a comparison with a > certified gauge, nor did we replace the gauges on the wet pipe. > > The chart is supplied with the flow tester. > > Do these results look legitimate? A larger nozzle = more GPM and less PSI? > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
