GB473480A - Improvements in the cleaning of filters - Google Patents

Abstract

473,480. Filters. CANDY, F. P. March 13, 1936, No. 7556. Addition to 437,275. [Class 46] The arrangement for cleaning filter-beds comprising a layer of sand on a supporting layer of coarser medium by a simultaneous air scour from a pipe reticulation in the sand and a water upwash from a pipe reticulation in the coarser medium, as described in the parent Specification, is provided with means for flushing away any sand which enters the airsupply pipes. As shown in Fig. 1, air-supply pipes d extending outwards from a header g are connected at their ends to conduits m, n, one or both of which are provided with a valved outlet through which sand in the air pipes is flushed by water, supplied either through the header g or one of the pipes m, n, or entering through the perforations of the pipe d. Air may be supplied to the pipes d through the conduits m, n. The header g may be provided with a flush outlet. Alternatively, the ends of the pipes d may be turned down and left open, as shown at the right hand of Fig. 2, or turned down and connected loosely to a pipe P, as shown at the left hand of Fig. 2, the flush water being supplied through the header g. A further modification is described in which the central header g is omitted, the conduit m has downwardly-turned open ends and the conduit n has one downwardly-turned end with a non-return valve and a fluid-discharge valve at its other end, both conduits m, n having connections for the supply of compressed air. With this arrangement there need be no independent supply of flushing water as water will enter the conduit m from the bed and sand will be flushed away through the conduit n.