An orifice meter with a diameter of 3 in. is mounted in a 4 in. sch 40 pipeline carrying an oil with a viscosity of $30 \mathrm{cP}$ and an $\mathrm{SG}$ of 0.85 . A mercury manometer attached to the orifice meter reads $1 \mathrm{in}$. If the pumping stations along the pipeline operate with a suction (inlet) pressure of $10 \mathrm{psig}$ and a discharge (outlet) pressure of $160 \mathrm{psig}$, how far apart should the pump stations be, if the pipeline is horizontal?