The practical application of robust control design methodologies depends on the ability to develop suitable models of physical systems. Model validation provides a means of assessing the applicability of a given robust control model (nominal model with linear fractional norm bounded perturbations and norm bounded unknown inputs) with respect to an input-output experiment. This paper describes the practical application of the model validation theory (for H-infinity/mu framework models) to a laboratory process control problem. A discrete-time frequency domain approach is used. Two candidate robust control models are postulated for the system. An experiment is performed and the theory is used to quantitatively assess the applicability of each of the candidate models.