Problem 1.60
Pipelines are cleaned by pushing through them a close-fitting cylinder called a pig. The name comes
from the squealing noise it makes sliding along. Ref. 50 describes a new non-toxic pig, driven by
compressed air, for cleaning cosmetic and beverage pipes. Suppose the pig diameter is 5-15/16 in and
its length 26 in. It cleans a 6-in-diameter pipe at a speed of 1.2 m/s. If the clearance is filled with
glycerin at 20C, what pressure difference, in pascals, is needed to drive the pig? Assume a linear
velocity profile in the oil and neglect air drag.