7.6. 96,000 lb/hr of 35API absorption oil is being cooled from 400 to 200°F and is used to heat 35API distillate from 100 to 200°F. Available for the service is a 29 in. ID 1-2 exchanger having 338 tubes 1 in. OD, 14 BWG, 16'0 long on 1-in. triangular pitch. Baffles are spaced 10 in. apart, and the bundle is arranged for four tube passes. What arrangement gives the more nearly balanced pressure drops, and what is the dirt factor? The viscosity of the absorption oil is 2.6 centipoise at 100°F and 1.15 centipoise at 210°F. Plot on logarithmic paper F vs. viscosity in centipoise, and extrapolate as a straight line. The viscosity of the distillate is 3.1 centipoise at 100°F and 1.3 centipoise at 210°F.