Improvements in Filters

12,251. Jandus, W. July 6. Tap &c. filters; filter blocks, forms and construction of; cleansing; air supply. - The tubular filtering-block 16 has its outer surface longitudinally grooved, and its inner surface circumferentially grooved, whereby an increased filtering - area is obtained. The water filters outwards, and the outer surface of the block can thus be open to the access of air through the space between the two halves of the casing. To enable the block to resist the internal pressure, it is surrounded by a jacket, preferably of wire. Water enters at 5, and is deflected upwards by a plate 6. Unfiltered water is drawn off through the valve 15, which is opened by turning the cup 21 screwed by a quick thread on to the casing. At the same time the filter block is scraped by sets of plates 34, Fig. 2, conforming to its corrugations and carried in boxes 33, formed by plates sliding on a hexagonal part of the valve spindle. The plates 34 are pressed outwards by springs, and carry bolts engaging in L-shaped slots 36, so that they can be retained in a retracted position when desired.