Abstract: A dispenser for fluid material includes a flexible container. A piston is adapted for movement within the container. An expansible bladder is connected to the piston. A first flow restrictor allows flow of displacement fluid only from outside the container into the interior of the bladder. A second flow restrictor allows flow of material only from within an interior portion of the container external to the bladder to outside the container. The container also preferably includes a rod supported in the container, the piston being movable on the rod. In another embodiment the bladder is connected to a collar movable on the rod.