4.11 A gravity-feed piping system between two large tanks is used to transport a 20% magnesium chloride solution as shown in Figure P4.11. The magnesium chloride is at 80°F and the tanks are open to the atmosphere. The piping system is 2½-nom sch 40 commercial steel. All fittings and valves are 2½ nom.

The total straight length of pipe in the system is 60 ft. The elevation difference between the free surfaces of the tanks is 15 ft. Determine the volumetric flow rate (gpm) between the two tanks.