In the early stages of a filtration cycle, it frequently happens that the filter resistance is
large relative to the resistance of the filter cake because the cake is thin. Under these
circumstances, the resistance offered to the flow is virtually constant and so filtration
proceeds at a more or less constant rate. Equation (10.12) can then be integrated to
give the quantity of liquid passed through the filter in a given time. The terms on the
right-hand side of eqn.(10.12) are constant so that integration is very simple