A theory is proposed which uses both the permeability and bubble point
diameter of the porous plug to characterize the full range operation
of the Vapor Liquid Phase Separation (VLPS) of liquid helium. A comput
er model has been written based on the theory presented in this paper,
which gives good correlation with VLPS data in the literature. The pr
edicted performance of the SIRTF flight plug is also presented. (C) 19
98 Elsevier Science Ltd. All rights reserved.