As scour air is introduced into the plenum of false floor underdrain systems, it collects and builds an air blanket evenly across the filter footprint and downward from the top of the plenum, displacing the water. In the video, one may see an air blanket in a test column in our Orthos Research Center.
Scour air enters the nozzle through metering holes or slots manufactured in the nozzle tailpipe. The size and location of these holes determine the depth of the air blanket at a specific air flowrate per nozzle. Once air scour is terminated, the residual blanket above the top metering hole is evacuated through an air bleed hole located at the top of the nozzle tailpipe.
Orthos has developed a proprietary, calibrated software model that calculates blanket depths at varying air flowrates for a specific nozzle tailpipe construction.