We have a municipal water system which operates at 48 psi most of the time, however when the flow exceeds 350 Gpm the fire pump kicks in and boosts the system to 145 Psi, @ 2000 gpm. Whenever a flow test is performed the results are always based upon the fire pump flow. As we all know most fires are contained or extinguished by one to three heads. Obviously this isn't enough to make the fire pump kick in. The local Fire Chief has started to question the operation of systems installed using the full flow of the fire pump, since even in flow conditions over 350 Gpm it can take as long as 2 (Two) minutes for the pump to kick in. The bigger concern as I see it is that the design for any system up to 350 Gpm should be based upon "NO" fire pump, with two sets of calculations one for flow up to 350, and another for flow over 350. This way we can be sure that the sprinkler heads will have the min. pressure and flow even if only a few go off. The other calc should be easy to prove, as over 350 there will be a large increase in pressure available. The caveat is that the higher flow calculation cannot be used to reduce the pipe size below those used for the lower calc. It is just a "Proof" calc.
Does this sound like the right approach? No the city has no intention of changing the pump set up any time soon. Thom McMahon Firetech, Inc. 2560 Copper Ridge Dr Steamboat Springs, CO 80488-2136 Tel: 970-879-7952 Fax: 970-879-7926 _______________________________________________ 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)
