VORRICHTUNG ZUM FILTRIEREN VON FLUESSIGKEITEN

摘要

A filtration system for liquids employs a sealed tank that is partially filled with sand or the like to provide a filtration bed in the lower portion thereof. An underdrain device is buried in the bed of sand and prevents particles from passing outwardly from the bed with the liquid flowing through the system. One end of a vent conduit is attached to the underdrain device from which it passses upwardly through the sand to a point near the top of the tank. Air introduced into the tank escapes automatically through the vent conduit, thus eliminating the need for the valves which are conventionally provided in the upper portion of such tank filters for the same purpose. The filtration system includes a particulate or sand filter unit coupled with a fabric type filter to remove very fine particles from the liquid removed from the liquid treated in the sand filter unit. The system is particularly adapted for use with swimming pools, and is capable of removing very fine particles from water flowing at high rates through the system.