| 摘要 |
The filter includes a filtering layer of granular material supported on a nozzled base that sits above an inlet chamber for liq. to be filtered. Above the filter layer is a filtrate accumulation chamber also acting as a header for back washing of the filter layer. A filtrate outlet is fitted at the height of the free liq. level in the accumulation chamber. A back-washing pipe connects into the inlet chamber and extends up to a return elbow positioned below the free liq. level in the accumulation chamber. In this pipe is a non-return valve that opens when a predetermined press. is reached in the inlet chamber to allow back-flow of filtrate from the accumulation chamber. Connected into the elbow from the accumulation chamber is a flow break pipe that stops the back-washing when the level of the liq. in the accumulation chamber falls to a set level. Used for the gravity filtration of silted water. System shortens the back-washing pipe and does not require then intermediary lid of the filter chamber necessary in past installations. A more reliable press. loss is obtd in the filter layer simply by keeping the inlet water under high pressure. |
