Abstract: The strainer assembly comprises a body (1) which is to be mounted in the floor (14) of the filter and which has open upper and lower ends. A hollow open ended stem (3) has an external screw-thread (4) which engages with an internal screw-thread (2) in the body. The stem projects outwardly from the body below the lower end of the body and is axially adjustable relative to the body so that the effect of filter construction errors can be eliminated. A flexible tab (11) on the stem engages with ribs (10) on the body to prevent unintentional relative rotation of the stem and body. A strainer (8) is fitted to the upper end of the body and a flow control orifice (5) is provided in the stem. The area of the orifice is smaller than the total open area of the strainer.

Abstract: A bipolar cell comprising a plurality of spaced electrode plates defining a sinuous flow path therethrough, wherein the flow path sweeps out the entire space between adjacent plates so as substantially to prevent the formation of stagnant areas and thus minimize the growth of precipitate between the plates.

Abstract: Variable stroke pumping apparatus suitable for pumping chemicals in a pulseless manner irrespective of the stroke. The apparatus comprises a plurality of pumps connected in flow paths extending between a fluid inlet and outlet and a central housing containing a cam and cam follower devices mounted on a carrier which is pivotable to alter the stroke of the pumps while maintaining substantially constant aggregate pumping of the pumps. Pump reciprocating members for each pump, e.g. rams extend outwardly of the housing and are reciprocated by the cam follower devices.