This paper presents a correlation for the relaxation time which is a closure law for the homogeneous relaxation model (HRM). The HRM takes into account the non-equilibrium evaporation leading to the metastable liquid conditions. The purpose of this paper is to present the closed HRM and to show comparisons between its results and some available data. The possibility of the HRM to predict the critical mass-flow rates and the pressure distributions for one-dimensional hashing water flow has been validated. Although the model involves the use of several correlations (friction, heat transfer and the relaxation time), no adjustment of parameters against the data used for the comparison has been needed.