AN analysis of the residence time distribution of a tracer -£*in the fluid flowing through a continuous flow system is one of the important tools in the study of dynamic and dispersion characteristics of the system. The residence time distribution is defined as the fraction of a tracer material introduced into a system at a dimensionless time 6 = 0 which appears at the outlet of the system between 6 and 6 + d6.> 2 The tracer materials may be radioactive isotopes, electroconductive materials, dye stuffs, temperature variations, etc. If the injection of a tracer into the flow system is in the form of an impulse function such as a Dirac delta function, the response at the outlet of the system to the input commonly called the C(0) function is identical to the residence time distribution function (RTDF).' 2 Similarly, if the tracer is continuously applied to the inlet of the system in the form of a step input, the response at the outlet of the system is called the cumulative residence time distribution function or the F(0) function. The F(0) function and C(0) function are related as' 2 C(0) = [dF(6)/d6] (1) Since the residence time distribution function may be directly related to the degree of the tracer distribution either in longitudinal or transversal direction or both, it can be used to develop models to represent the dispersion and dynamic characteristics of flow systems.