Question

A rectangular pool, 10 m x 30 m, is to be filled to a depth of 3m.

a) For a filling time of 2 hours, determine the inlet flow rate required in m^3/s

b) If 6-cm diameter hoses are available, and the water velocity in each hose is not to exceed 3 m/s, determine the number of hoses required.

Answer 1

a) inlet flow rate = volume / time

volume = 10 x 30 x 3 = 900 m³

time = 2 hours = 2 x 60 = 120 sec

inflow rate = 900/120 = 7.5 m³/s

b) no of hoses required = inflow rate / flow from each hose

flow from each hose = area of each hose x velocity of water in each hose

area of each hose = π d²/ 4

diameter d = 6 cm = 0.06 m  

area of each hose = 3.14 x 0.06²/4 = 0.002826 m²

flow from each hose = 0.002826 x 3 = 0.008478 m³/s

no of hoses required = 7.5 / 0.008478 = 884.64 = 885

885 hoses required