Extracted text: Flow from a tank with falling head. For the tank shown in figure below, find the time required to drain the tank from a level of 3.0m to 0.5 m. The tank has a diameter of 1.5 m and the nozzle has a diameter of 50 mm. FIGURE 6.14 dh D, Assumption: Equation developed by assuming that diameter of fluid flowing from the nozzle is the same as the diameter of the nozzle itself. This is a very nearly true assumption for a well-rounded nozzle as shown in this and earlier figures.