Table 6.2 shows the typical volume flow rate for centrifugal fire-fighting pumps is in the range of 1800 L/min to 9500 L/min. Specify the smallest suitable DN size of Schedule 40 steel pipe for each flow rate that will maintain the maximum velocity of flow at 2.0 m/s.

TABLE 6.2 Typical volume flow rates for a variety of types of systems Flow rate Type of system (m/h) (L/min) (gal/min) Reciprocating pumps-heavy fluids and slurries 0.90-7.5 15-125 4-33 Industrial oil hydraulic systems 0.60-6.0 10-100 3-30 Hydraulic systems for mobile equipment 6.0-36 100-600 30-150 Centrifugal pumps in chemical processes 2.4-270 40-4500 10-1200 Flood control and drainage pumps 12-240 200-4000 50-1000 Centrifugal pumps handling mine wastes 2.4-900 40-15 000 10-4000 Centrifugal fire-fighting pumps 108-570 1800-9500 500-2500