| 摘要 |
437,275. Filters. CANDY, F. P., 14, Church Road, Hanwell, London. April 23, 1934, No. 12101. [Class 46] A filter having a layer b of fine medium, such as sand, on a layer a of coarser medium, such as gravel, is fitted with a pipe reticulation c below the gravel for the collection of filtrate and the distribution of up-wash water and with a pipe articulation d below the sand for the distribution of air during the up-wash. The wash water is supplied through the filtrate outlet e and the air through pipes f, g. Fig. 2 shows one form of pipe for the arrangement d. The perforations h are formed in separate cupshaped depressions or in a continuous groove in the lower half of the pipe and intermediate the transverse and vertical axial planes, and the pipe is surrounded by a sleeve j with smaller perforations. Fig. 3 shows a modified form of pipe in which the perforations are along the bottom of the pipe and protected against the entry of sand by shields k, which may take the form of a continuous channel. With a view to preventing the choking of the perforations in the pipes d with sand, arrangements may be made for supplying water through the pipes d after the supply of air has ceased but before the water supply through the pipes c is cut off. |
