It is shown that the basic equations governing the flow of a two-phase fluid, i.e., liquid and vapor, are natural extensions of those equations that describe single-phase flow. The exact form of the equations depends on the particular assumptions used to characterize the two-phase flow, i.e., the equations depend on the model chosen. In general the mathematical model is selected so as to retain as much of the physics of the phenomena as possible while at the same time permitting solutions to be obtained without undue complexity. The following quantities were computed for saturated water substance over the temperature range 100 to 250/sup 0/C and for saturated Refrigerant -114 over the range -20 to +70/sup 0/C: choking velocity, critical or choking flow density, and saturation properties. Tables of the results are given along with graphs of selected functions.