Recommended Use For diameters of 4" (100mm) and 6" (150 mm), with two outputs of 2 1/2" and an output of 4 1/2", with minimum flow rates of 1000 GPM, and for diameter 3" (75 mm) with two outputs of 2 1/2" whose minimum flow rate is 500 GPM, these flows for the maximum operating pressure of 150 PSI. Boston hydrant can be used to expel larger solids because of its spherical shape in the seal zone. Its application is in industrial, commercial, residential sectors and in urban, rural areas with low and high population densities.