| 摘要 |
An underdrain lateral for a liquid purification system is described. The lateral has three chambers, a primary chamber, a compensating chamber, and gas chamber. Turbulence is minimized during cleansing of the purification media by isolating the gas from the liquid and the backwash liquid. This is accomplished by feeding gas into the gas chamber so that the chamber is occupied by gas only during cleansing. Orifices in the wall between the primary and compensating chambers and in the baffle between the compensating and gas chambers provide compensation for even distribution of liquid in the lateral. The design also enables the use of cut out in the gas chambers to equalize gas pressures and flow among the laterals and throughout the system bed and cut outs in the primary chambers to equalize liquid pressure and flow along the laterals and throughout the system bed. Nozzles with threaded stems having gas inlet orifices may be used and the levels of the entrances to the nozzles adjusted by rotating the stems to equalize backwash liquid flow among the nozzles. To minimize liquid pressure for greater gas flow during cleansing, an insert in the stem, adjacent the gas inlet orifices, may be added.
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