$SG=2\mathrm{.}4$

A sharped edged $0\mathrm{.}5$ inch orifice is installed in al inch standard steel pipe. Dry air at upstream condition of $20C$ and $2$ atm flows through the orifice at such a rate that the $U$ tube manometer connected across the taps indicates a reading of $30$ cm of red oil. The red oil has a specific gravity of $0\mathrm{.}831$ referred to water at $20C.$ Assume that the orifice discharge coefficient $C_0$ is $0\mathrm{.}61.$

$($i$)$Calculate the weight rate of air flow in the pipe.

$($ii$)$ Estimate permanent head loss across the orifice