5. An orifice meter is used to measure the flow of water in a horizontal pipe as shown in Figure 4. Show that the actual flow in the pipe is given by 2gH Q=C4411 m2 -1 where Cd = coefficient of discharge of the orifice meter, H = pressure head difference between 1 and 2, m = area ratio A1/A2, A = area of the pipe, A2 = area of the orifice meter. 2 water Figure 4 In the above, the diameters of the pipe and orifice meter are 250 mm and 100 mm respectively. The coefficient of discharge of the orifice meter is 0.65. The pressure head difference across the orifice meter is 760 mm of mercury (specific gravity 13.6). Calculate the rate of flow. Answer (0.0735 m/s)