an apparatus is provided for use with a device for dispensing fluid from a container with an open end and a closed end . a follower is movably disposed in the container and fluid is held between the follower and the open end of the container . an air inlet opening is provided between the follower and the closed end of the container . the apparatus comprises a housing defining a piston chamber , a piston disposed for reciprocal movement in the chamber and an actuator movably mounted to the housing for reciprocating the piston . the housing has an air inlet duct , an air outlet duct , a fluid inlet duct and a fluid outlet duct , all of which open into the chamber . the housing sealingly mounts to the open end of the container such that the interior of the container is in fluid communication with the fluid inlet duct . the piston sealingly engages the chamber walls at two longitudinally spaced locations for dividing the chamber into a first volume and a second volume . the air inlet and air outlet ducts open into the first volume and the fluid inlet and fluid outlet ducts open into the second volume . the piston forces air through the air outlet duct and fluid through the fluid outlet duct when it moves into the chamber and draws fluid into the chamber through the fluid inlet duct and air into the chamber through the air inlet duct when it moves out of the chamber .