Air diffusion unit and control mechanism therefor

DETAILED DESCRIPTION In accordance with this invention, the structure of each diffusion module has been standardized and has been designed to allow quick and easy air flow adjustment.
Measurements of the amount of air passing through each module is greatly simplified.
A balanced distribution of air from all of the modules in a work space is achieved for the diffuser module disclosed by this invention by controlling the admission of air into an upper control plenum ahead of a lower distribution plenum within the module.
Air from a pressurized source passes through the inlet and valve to the upper control plenum having an area equal to the module size.
This upper chamber has two symmetrically located elongated openings equal in area.
These two openings allow air to flow into two hinged air diffusion units having a perforated outer surface.
The air flows from the diffusion unit into the lower distribution plenum having as its bottom side a perforated diffusion plate which is contiguous with the ceiling of the work space.
During the balancing operation, all diffusion plates and diffusion units are opened to allow complete exposure of the elongated opening from the upper control plenum.
Because of the relative small area of this opening with respect to the total surface area of the diffusion plate, there is sufficient air velocity through the opening to be measured by a standard anemometer.
This opening has an effect of an orifice.
When the modules are all the same size, it is a simple matter to adjust the air volume control valve so that the average of the readings from the anemometer at each orifice opening within a module approximately equals the other average readings.
If the modules vary in size, it is necessary to apply a correction factor to the reading if the outputs are to be balanced.
A module with a greater outlet surface area must be supplied with more air than that of smaller module.
Therefore, the velocity of air through the orifice opening of a larger unit must be relatively greater than the velocity of air in a smaller unit if the orifice opening is the same size