PUMPS

A rotary pump (10) comprises a housing (20) having a first (21) and second fluid port (22) and an interior surface defining a cavity (24) in which a rotor (30; 230) is located, wherein the rotor comprises at least a surface recess (231a-231d) forming at least a fluid-conveying chamber (232a-232d) with the interior surface of the housing. The pump further comprises at least a resiliently deformable diaphragm (50): 226) providing part of the interior surface of the housing and being urged into contact with the surface of the rotor by the action of pressurising means acting on the rear surface of the resiliently deformable diaphragm. The pump further comprises one or a pair of flow channels (41a, 41b; 241a, 241b) associated with the resiliently deformable diaphragm extending longitudinally from opposite ends of the rotor. In embodiments where the pump comprises one flow channel (575), the flow channel is in fluid communication with the first fluid port and an aperture (595) opens from the interior surface of the housing to place the second fluid port in direct fluid flow communication with the fluid-conveying chamber. In embodiments where the pump comprises a pair of flow channels (241a, 241b), the pair of flow channels comprise a first flow channel in fluid communication with the first fluid port and closed to the second fluid port and a second flow channel closed to the first fluid port and in fluid communication with the second fluid port, with each flow channel being located at opposite sides of the diaphragm. Embodiments of the invention exhibit continuous fluid flow when in use.