Water at 10C is to flow from reservoir A to reservoir B through a cast-iron pipe (= 0.26 mm) of length 20 m at a rate of 0.002 m/s. The system contains a sharp-edged entrance (K = 0.5) and six regular threaded 90 elbows (K = 1.5) and a sharp-edged exit (K = 1) as shown in Figure 2. Detemine the pipe diameter D needed. (Hint: Use trial-and-error method to solve for D based on the expressions developed from head loss consideration.) Elevation z1 = 2 m Total length = = 20 m (1) Elevation z, = 0 m D(2) B Figure 2