Abstract: Contaminants are removed from a liquid (12) in a storage vessel (14), by using a working liquid to varying the volume of a working cavity (44) sequentially inside a working vessel (16) and using the variations in the volume of the working cavity (44) to vary the volume of a suction cavity (20). The working cavity (44) is defined in a working vessel (18) and the suction cavity (20) is defined in a suction vessel (26) and the vessels (16, 18) are configured so that the volumes of their internal cavities (20, 44) are inter-dependent. Using non-return mechanisms (26, 36) to ensure one-way from the storage vessel (14) via the suction cavity (20) to a filter (28) and back to the storage vessel (14).

Abstract: A barrier system is disclosed which is fitted to the filler opening (12) of a fuel tank (10). The system comprises an outer sleeve (34) in the form of a coil spring (36) and lining (38) which is of a material that permits fuel to flow through it but which retains water and solid contaminants A valve (52, 54) is provided at the lower of the sleeve (34) for enabling accumulated water and solid contaminents to be drained from the sleeve (34).

Abstract: A separator (10) for separating a heavier liquid from a lighter liquid is disclosed which is intended to operate between a fuel tank (12) and a fuel pump connected to the fuel outlet (24) of the separator (10). The separator includes a float (30) which is light enough to float on the heavier liquid and which is heavy enough to sink in the lighter liquid. The float controls opening and closing of a valve (44, 46) through which heavier liquid is disclosed from the separator. As heavier liquid accumulates, the float lifts to open the valve (44, 46). A plate (34) subjected to a force caused by fuel flowing into the separator through the inlet (16) prevents the float opening the valve whilst the separator is in sub-atmospheric pressure. The plate can be replaced by a diaphragm which is subject on one side to atmospheric pressure and on the other side to the pressure in the separator.