Abstract: Liquid dispensing apparatus is disclosed having at least one liquid dispensing chamber and an associated prefill chamber with displacement mechanism for transferring liquid therefrom to the dispensing chamber. The dispensing chamber is in communication with the prefill chamber over a weir so that liquid in the dispensing chamber in excess of a predetermined measure flows back over the weir to the prefill chamber. The dispensing chamber has an outlet openable and closable by a seal to dispense the measure held in the dispensing chamber.

Abstract: An oscillatory pump includes a cylinder (9) having normally-closed valves (10,13) of flexible material fixedly located at the inlet (A.sub.c) and outlet (B.sub.c) ends of the cylinder (9), and a piston (1) having an inlet (A.sub.p) and an outlet (B.sub.p). The piston (1) is reciprocatable within the cylinder (9) and is provided with a further valve (6) of flexible material movable with the piston (1) and located at the outlet end (B.sub.p) of the piston (1). The piston (1) is constructed to allow fluid to pass from an inlet chamber (C1) formed between the inlet valve (10) and the inlet end (A.sub.p) of the piston (1) to an outlet chamber (C2) formed between the further valve (6) and the outlet valve (13) in response of the piston (1) within the cylinder (9). The valve includes a valve seat having a generally conical first surface portion and a second surface portion located radially inwardly of the first surface portion and extending generally parallel to the axis of the first surface portion.