The Aeration Unit “PEAI” allows the study of the oxygen transfer characteristics of diffused air systems, and the physical and chemical parameters, which influence oxygenation capacity. PEAI unit demonstrates the water aeration process which, mainly, eliminates smell and taste from water. The main component of the unit is the central tank where the liquid subjected to study will be poured, usually water. An air pump, located underneath the tank, injects air in the tank. The air-injection tube passes previously traverses a device that measures and conrol the injected air, allowing the manual control of the volume of air that is allowed into the tank. After the air flow controller, the air is led through a flexible tube to the upper inlet of the tank. There, three different air outlets can be connected, in order to disperse the air in a different ways (three type of diffusers are supplied). On the other hand, there is a stirrer, with variable speed control, in the middle of the tank. The main part of the stirrer is a motor that makes it turn inside the tank. Finally, there is an oxygen-meter to measure the oxygen dissolved in the water and a temperature meter.