Two mathematical formulations for the computation of transient flow in piping systems are compared with experimental data. The formulations are: a four-equations fluid structure interaction model (FSI) that includes Poisson coupling, and a two-equations model for the fluid. Both models are solved numericaly using the method of characteristics. A partial-closure of a valve located at an intermediate point in a pipeline is used to create transient flow. The two-equations model computed the maximum pressure peak satisfactorily but the FSI model gave an overall better simulation. An unsteady-friction model, added to the FSI model, did not influence the final results significantly. The experimental procedures followed to obtain the valve characteristics and the pressure history along the pipeline are explained in detail. Excellent numerical results at the valve are obtained when experimental data is used to simulate the time-dependent boundary condition.