The main purpose of this paper is to evaluate the main fluid mechanics parameters in the exit region of three different terminal systems commonly used for controlled environments such as clean rooms or operating theatres. Three different types of diffuser were tested i.e. a diffuser grid, a square ceiling diffuser and a swirling radial discharge diffuser. The paper presents results obtained experimentally which were carried out in order to study the flow characteristics of isothermal jets issuing from such devices. The study has been performed for four different air flow rates for each type of terminal tested. To characterise the flow with confidence and obtain high spatial resolution, a Particle Image Velocimetry technique and a Laser Doppler Velocimetry technique were used. For each case investigated, the results were plotted as velocity profile, velocity magnitude, turbulence intensity and vorticity. The study displays the particular behaviour of the flow generated by each terminal. Vorticity regions and turbulence spots were also detected and carefully localised for the investigated configurations.