A fan blows air $((=1\mathrm{.}25$

kg$/$m$3)$ through a pipe of $250$ mm in diameter in which a

diameter pipe in which an orifice plate is installed. The orifice plate orifice is $150$ mm in diameter concentric to the pipe.A pressure gauge

connected upstream and downstream of the plate indicates a pressure difference of $8$ mbar. The discharge coefficient of the plate is $0\mathrm{.}65.$

discharge coefficient of the plate is $0\mathrm{.}65.$ Calculate the flow rate of

fan