This paper is dedicated to the comparison between experimental data and numerical results in multi-phase flows involving high pressure ratios such as water hammer transients. A two-fluid seven equation model has been selected due to its ability to take into account all phasic desequilibria as well as vanishing phases. Theoretical properties of the model are underlined. A mono-dimensional finite volume implementation of the two-fluid model is then compared to the experimental data of the Simpson and Canon experiment. Differences with the classical Baer and Nunziato model are also pointedout.