Patent ID: 7278985

Claim:
A medical pump, comprising: a reservoir having a fluid enclosing portion; a tubular element, the inside of which is arrangeable in fluid communication with the fluid enclosing portion for allowing fluid to pass into the tubular element; an inner seal movable inside the tubular element between an advanced and a retracted position, wherein the inner seal is retractable from the advanced position to enable the fluid to be transferred from the fluid enclosing portion into an internal space defined by the tubular element and the retracted inner seal, and wherein the inner seal is advanceable from the retracted position for delivering out of the pump fluid present in said internal space; wherein said fluid enclosing portion contains a volume of fluid sealed from communication with air and the fluid enclosing portion is adapted to reduce in volume essentially to the same extent as any volume of fluid transferred into said internal space of the tubular element; wherein said fluid enclosing portion comprises a outer seal which is movable inside the reservoir and which defines a delimitation of the fluid contained in the fluid enclosing portion, the outer seal being arranged to move relative to the tubular element when the inner seal is retracted from said advanced position; wherein the tubular element is located inside the reservoir, wherein the outer seal extends from an inner surface of the reservoir to an outer surface of the tubular element; wherein the tubular element is movable between an advanced administering position and a retracted filling position, wherein the outer seal is adapted to move relative to the tubular element when the tubular element is retracted from said administering position; wherein mutually contacting surfaces of the tubular element and the outer seal provide a frictional force F 2 against advancing movement of the tubular element towards its administering position, and wherein mutually contacting surfaces of the outer seal and the reservoir provide a frictional force F 3 which is smaller than the frictional force F 2 , wherein the outer seal is advanced together with the tubular element during advancement of the tubular element towards its administering position; and wherein the reservoir has an outlet covered by an abutment surface that obstructs a fluid flow from the outlet and into the reservoir.