GB298835A - Improvements in filters - Google Patents

Abstract

298,835. Bramwell, B. Feb. 7, 1928. Filters with loose filtering- materials. - Sand or other filtering-medium is washed in an open-ended tube, situated within the filter chamber, and up which the medium is carried by a stream of clean water directed upwardly into the tube from a nozzle. As shown in Fig. 1, the base of the filter A is spherical and the corners are rounded off by asphalt fillets E, so that during cleaning the sand passes readily towards the injector F, which lifts it up a washtube G for re-distribution over the top of the bed by a deflector J. During filtering the water under treatment enters by a pipe L, filters downward through the bed, and passes away through a perforated partition B and a pipe D. The corner above the annular filtrate chamber is filled in with a fillet E<1>, the surface of which is continued downward by a conical shield H. The flow through the pipes L, D and the pipe F', through which clean water is supplied to the injector, is controlled by a single rotary valve M. During cleaning, dirty water separating from the sand above the bed is discharged through a pipe K. It is preferred to arrange for a supply of clean water to the filtrate chamber to give a reverse upward flow through the medium during cleansing. A filter may be provided with several injectors and wash pipes, the bottom of the filter being suitably contrived to direct the sand to the several nozzles. Motion of the medium towards the injector or injectors may be aided by suitably directed auxiliary jets. In the filter shown in Fig. 5, the sand is supported on a false bottom formed of two perforated plates with an interposed sheet of gauze. The floor of such a filter may be shaped to form a cone around each of the injectors. The rotary valve M, Fig. 1, may be automatically actuated to control the periods of filtration and cleansing by a device shown in Fig. 8. The valve is actuated by a rod Z connected by suitable linkage with a piston O<1>. When the pressure in the filter chamber rises above a predetermined level, water passes through a pipe T and valve R to below the piston O<1> raising the piston, and with it a bucket Q, and, by means of tappets Q<1>, I<1>, a tappet-rod I operating valves R, S. The rod I, on raising, shuts off the space below the piston from the pipe T and opens it to a waste pipe U. It also opens the valve S to supply liquid to the bucket Q. With the fall of the bucket and piston the valves R, S are again reversed. Resistance to the movement of the piston O<1> is controlled by a regulating-cork W in a pipe connecting the upper end of the piston cylinder with an open tank above it.