NFPA 20 (yr 2013) Table 4.26a has recommended minimum pipe sizes of discharge pipe according to pump flow rate. Does that mean that is the minimum size of the fire water main. For example if our pump flow rate is 2000 USgpm for which the table recommended minimum size of discharge pipe is 10 inch, should we run a pipe of 10 inch throughout the premises? I understand we can not reduce the pipe size for the same flow at any point in fire protection, therefore we should run minimum 10 inch pipe to all buildings being served through this fire pump.
In addition to this, if the sprinkler demand is 1450 USgpm, does that mean that the cross main should be of 8 inch minimum because the same table of NFPA recommends a pipe size of 8 inch for 1500 USgpm pump flow?