# ProblemSet9_soln_20.pdf - ECH 141 Problem Set#9 1 Two...

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ECH 141 Problem Set #9 1. Two immiscible liquids A and B of specific gravities 0.8 and 1.0, respectively, flow into a closed tank in which they separate into two layers. Pure A and pure B are taken off by pipes which discharge to atmosphere at a point 5 ft below the A/B interface in the tank. The flow in each pipe is controlled by an orifice. Calculate the size of the orifice discharging B when the one discharging A is 1 inch in diameter and the total feed is 5000 lbs/hr containing 60% by weight of A. The outlet pipes are nearly identical, and are much larger than the orifices. The orifice discharge coefficients are each C D =0.6, so that if the head loss across the orifice is h O , then the velocity v through the orifice is given by the orifice equation (similar to Torricelli’s law, see Eq. (8.5-15) in text), v = C D 2gh O . Note that since h O = 1 C D v 2 2g , this orifice equation corresponds to a loss coefficient K (i.e., fraction of velocity head loss) of 1/C D . It may be assumed that none of the head loss across the orifices is recovered and that both fluids have