Hi! I know that: 1- As per NFPA-20 listed fire pumps shall furnish not less than 150 percent of rated capacity at a total head of not less than 65 percent of the total rated head to provide some safety factor in case of greater than expected demand at the time of fire. 2- On the other hand, NFPA allows to choose a fire pump working at 150% of rated capacity if it delivers the required water flow at required pressure to fire protection system. I think these two issues are against each other, because if I choose a pump which is working at 150% of rated capacity, then I have already overloaded the pump, so in case of greater than REQUIRED flow, it might not be able to supply this extra demand at not less than 65 percent of the total REQUIRED head. for Example if he required demand is 1100GPM at 100Psi, I can do as followings: * 1100gpm/1.5 = 733Gpm, so I will choose a 750GPM Pump. * 100psi/0.65 = 154Psi, so I will choose a 154psi Pump. I know it is not usuall to choose a pump working at 150% of rated capacity, and 135% is more common, this is just a scenario to ask my question. So the pump is rated at 750Gpm, 154psi and will work at 150% of rated capacity to supply my required demand of 1100Gpm at 100Psi. My question is that If in case of greater than expected demand at the time of fire the demand increases to 150% of required flow (1100 * 150% = 1650Gpm), then can I be sure than the total head is not less than 65 percent of the total REQUIRED head? Should I check it from the pump curve? Thanks for your attention, Reza
__________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com _______________________________________________ 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)
