Under-seat diffusers The distribution of air in auditoriums and cinemas has always been a complex problem to solve due to technical and architectural limitations. The use of under-seat PDP diffusers, thanks to their features, fully meets the requirements of these environments. The system foresees the inlet of air, coming from the air conditioning system, directly at the base of the seat, generating a micro-climate effect around the seat. Basically, primary air enters from the bottom part of the cylindrical body, which is fitted with an internal swirl diffuser (static) which changes the direction of the air sending it towards the perforated part of the cylinder; this air motion creates a depression at the center of the diffuser which is fitted with an up-side down cone that takes air from the room and mixes it with the primary air. This generates a pre-mixed flow that is distributed on the entire perforated surface before entering the room. The specifications of this system are: • Maximum comfort near people • Limited noise level Lw equal to 15 [dB(A)] with a specific pressure of 40 m3/h • Limited residual speeds and a limited temperature gradient. You don’t need to condition all the volume of the room because these devices operate with a micro-climate effect in limited areas, the temperature difference between room and inlet air can reach 7 °C. The PDP diffuser has limited sizes and can be installed as a seat support or in other ways. In any case the architect can freely chose any kind of seat type. Technical draft