999,759. Filters for liquids. FISONS FERTILIZERS Ltd. Dec. 20, 1961 [Dec. 13, 1960], No. 42925/60. Heading BID. An apparatus for automatically obtaining clear liquid samples from liquids containing suspended solids comprises a coarse foraminous filter 1, e.g. of stainless steel mesh or cloth, attached to a source of supply of the liquid to be sampled and provided with a line 2 branching into lines 3, 4 connected to the apex of a dirty initial filtrate receiver 5 and to the lower part of a clear subsequent filtrate receiver 6 respectively, the receivers both being connected to a vacuum/compressed air line 9 at their apices, via branch lines 7, 8 respectively, and each being provided with exit lines 20, 26 respectively from their bases, solenoid valves 12, 13 and pneumatically operated diaphragm valves 21, 24 being provided in the vacuum/ compressed air line and exit lines respectively. The operation of the valves is controlled by an automatic timing device 25 adapted to open valve 12, connected to a vacuum pump 14, thereby charging the filtrate receivers, while closing the valves 21, 24, and after a lapse of time sufficient for first the receiver 5 and then the receiver 6 to fill, closing the valve 12 and opening the valves 13, 21, 24 thereby causing the discharge of the liquid in the receiver 5 through the valve 21 to waste, and the discharge of the clear filtrate in the receiver 6 simultaneously through the valve 24 to the sampler and through the line 2 to backflush the filter 1. The valves 21, 24 are actuated by the pressure and vacuum under the control of solenoid valves 22, 23 operated by the timer 25.