The function of an Air Terminal Device (ATD) is to direct the incoming or exhaust air in such a way that comfortable conditions are maintained in the occupied zone of any conditioned space. Failure to choose a suitable ATD especially that used for supply purpose , may well nullify all other efforts to achieve comfort conditions in a room. At the same time , the ATD should be selected to suit aesthetic requirements. It is necessary at the selection stage to choose the position ( wall, ceiling, floor or cill) of the ATD's and the number, form and the type.
Consideration must be given to the occupancy of the conditioned space, and to internal features, such as irregularities of surface ,position of furniture and any source of heat loss or gain. Consideration should also be given to the method of fixing and to the finish of the ATD's.
No ATD can compensate for incorrectly designed duct entry conditions
air from linear slot diffusers discharges in a wide airstream which can be taken as two dimensional .The primary velocity reduction is in proportion to the square root of the distance from the linear slot diffuser . there is little increase in the width of the airstream.This type of Air Terminal Device has a length to width aspect ratio of 10:1 or greater.
Throw from the linear slot diffuser is taken to mean the distance from the device to the opposite wall.
Having taken into account, Throw, Drop ( if applicable) and position of linear slot diffusers in the ceiling, airflow rate can be established per unit length (m) by number of slots of the ATD to meet the design criteria .Note should be taken of the Noise and the Pressure characteristics.
To obtain the total length of "AIRTRON" Slot Diffuser, divide the total airflow rate per unit length (m). This total length can then be divided to suit the physical limitations and architectural requirements. The number of slots and the width of slot i.e.S-16 OR S-20 can be determined, again check Noise and Pressure data.