| 摘要 |
469,494. Filters. HOVEMAN, W. A., and HOVEMAN, F. C. March 18, 1936, No. 8099. [Class 46] In water-filtering apparatus of the type comprising horizontal layers of sand or like material, and provided with siphons for removing wash-water after cleaning of the filter, each siphon is accommodated wholly within the washwater channel, and is constructed to serve the two sections of the filter bed on opposite sides of such channel. The discharge of the siphons is automatically controlled by the differential hydraulic pressure set up in the filter bed during the cleaning operation. In one form, a shelf 1 extends across the upper part of the wash-water channel 2, and is surmounted by an arched roof 3 forming an enclosed chamber 7. Two banks 5 of concrete form a weir leading into a trunk or passage 6 of rectangular section. Wash-water passes from the filter bed sections 8 into the chamber 7 through flared slot-like passages 9, and thence through the trunk 6, an opening in the shelf 1, and a siphon tube 11 depending into a sealing cup or trough 13. In a modification, the trunk 6 and tube 11 are combined in the form of a single siphon pipe with an upper bell-mouth, while in a further modification constructed wholly of metal parts and particularly applicable to pressure filters, the chamber 7 is of mushroom shape, with a depending siphon pipe dipping into a cup. The siphons are controlled by air vents 16 fitted with check valves and connected to a common main pipe fitted with a regulating air valve, which is controlled automatically by a differential pressure device comprising a diaphragm or piston, the opposite sides of which are connected respectively to the underside and to the interior of the filter. When the pressures are equal, the regulating valve is open, but when cleaning water is passing in a reverse way through the filter, the valve is closed. The valve may be constructed to operate after sufficient time has elapsed to ensure resettling of the filter bed sand. |
