Book - School of Science and Technology

ADistribution for air-conditioning 417SupplyairVoid surfacessealedActive areas atmachine positionsPerforated metal tilesActiveareaSection A – APlan of computer roomFigure 15.11 Inlet via a perforated ceilingPerforated ceilingsProbably the most completely diffused form of inlet is the system which employs aperforated ceiling as shown in Figure 15.11. In this case air is discharged into the spaceabove the ceiling, which is usually divided up so as to ensure uniformity of distribution,and the air enters the room through the perforations. Where extremely large air quantitiesare involved the whole ceiling may be used, but in the normal case only selected areas ofpanels serve as inlets, acoustic or other baffles being positioned behind the `non-active'panels. The ceiling inlet system destroys all turbulence, which may be a good thing insome cases but not in others. This system has been applied successfully in law courts,department stores and in confined spaces such as radio commentators' boxes where noother distribution arrangements would be possible. An alternative to a perforated ceiling,but which achieves an equivalent effect, is the use of an array of strip diffusers, installed atsay 300 mm intervals. An example is shown in Figure 15.12.LuminaireStripdiffuserGridDischargeopeningsFigure 15.12 Ceiling distribution using multiple strip diffusers