An orifice meter is installed in a vertical section of a piping system, in which SAE 10 lube oil is flowing upward (at $100^{\circ} \mathrm{F}$ ). The pipe is $2 \mathrm{in}$. sch 40 , and the orifice diameter is $1 \mathrm{in}$. The pressure drop across the orifice is measured by a manometer containing mercury as the manometer fluid. The pressure taps are pipe taps ( $2 \frac{1}{2}$ ID upstream and 8 ID downstream), and the manometer reading is $3 \mathrm{in}$. What is the flow rate of the oil in the pipe in gpm?