Patent GB-782561-A (GB)
Title: Improvements in or relating to apparatus for filtering liquids
Inventor: BELDAM WILLIAM ROBERT
IPC: B01D35/12
Filed: 1952-10-16
Abstract: 782,561. Filters. AUTO-KLEAN STRAINERS, Ltd. Nov. 5, 1953 [Oct. 16, 1952], No. 26006/52. Class 46. [Also in Group XXIX] Liquid, for example oil, is pumped in at 5, Fig. 3, at a pressure of the order of 100 lbs. /sq. inch. It gains access to four filter chambers 2 through three ports 20 and one (shorter) port 20a in a valve element 19 and through four ports 18 aligned with them and provided in a valve housing 17. It flows inwards through cylindrical filter elements 10, Figs. 3 and 9 (one in each chamber 2), leaves each element by the aperture in an annular flange 11 to which the element is connected, the flange in turn being connected by walls 13 with a cover plate 14, and passes through a common outlet chamber 6 to an outlet 9. At any time prior to back-flushing one of the elements 10, a handle 26 provided on the spindle 22 of the valve 19 and having an arrow on one arm is rotated to indicate the selected element, the rotation also serving to bring the port 20a opposite the inlet port 18 of the chamber 2 containing the selected element see Fig. 3. This position, one of the four possible normal positions of the valve, is readily located by engagement of a pin 30 on the spindle 22 with the lower end of one of four grooves 31 provided in a stationary collar 24 and connected by an annular groove 32 in which the pin 30 moves between the grooves 31. The pin 30 is urged into, and retained in, any one groove 31 by a compression spring 28. The actual back-flushing operation is performed by raising the valve element 19 for a few seconds by a bifurcated lever fulcrummed at one end on the filter casing and engaging the underside of the handle 26. When the valve 19 is partly raised, Fig. 6 (not shown), a lower cylindrical extension 34 is raised just clear of a flushing outlet passage 17c while the conical end 34a of the extension closes the end of the passage. In this position the port 20a is just clear of its port 18 so that inward flow of the selected element is cut off. On continued raising of the valve to the uppermost position, Fig. 7, oil continues to flow into the other three elements while some of the filtrate from them is forced from the common outlet chamber 6 outwards through the selected element 10, through the port 18 and under the valve 19 to the flushing outlet 17c (maintained at a lower pressure than the chamber 6). The passage 17c may be maintained at atmospheric pressure but is preferably maintained at a pressure only slightly less (e.g. 5 lbs. /sq. inch less) than that in the chamber 6 by, e.g., a spring-loaded piston valve (see Group XXIX) connected between them and having an outlet to the main oil tanks at atmospheric pressure. The purpose of the pressure control is to prevent the rate of reverse flow from being too great and avoid the use of too much oil for the cleaning operation. Each filter element 10 may comprise a former 52 composed of a number of ribs 53, Fig. 9, to one of which a double circumferential length of coarse gauze 54 and a single length of fine gazue 51 are soldered in turn. The two are wrapped round the former 52, the fine gauze 51 being thus protected on the inside by the first turn of the coarse gauze 54 and on the outside by the second turn. The free ends of the gauzes are then soldered to the same rib as before. The contaminated oil from passage 17c passes into a sediment collector (not shown) which may be a filter such as is disclosed in Specification 575,167.