Patent ID: 7731699

Claim:
A valve assembly for use with a burette of a fluid delivery system, the burette having an inlet for providing the inflow of contrast media to the burette, a drip chamber for containing a volume of contrast media and a volume of air for permitting dissipation of air bubbles in the contrast media entering the drip chamber from tubing upstream from the burette, and an outlet for allowing passage of the volume of contrast media from the drip chamber to portions of the fluid delivery system downstream from the burette, the valve assembly comprising; a float positioned in the drip chamber of the burette, the float having an upper convex surface, a lower convex surface, and an outer circumferential rim positioned between the upper convex surface and the lower convex surface providing a desired amount of displacement between the upper convex surface and the lower convex surface, the juxtaposition of the upper convex surface, the lower convex surface and the outer circumferential rim forming a disk shaped configuration of the float such that the side profile of the float forms a substantially elliptical shape rather than a spherical shape or cylindrical, the float having a predetermined amount of buoyancy, the float being adapted to provide an impact surface for droplets of fluid passing from the inlet into the drip chamber while permitting the passage of fluid from the upper surface of the float to the lower surface of the float; and a seat configured to accommodate and provide support for the float when there is less than a predetermined amount of contrast media in the drip chamber, the seat and float forming an air tight seal between the drip chamber and the outlet of the burette to prevent the passage of air into the outlet of the burette when there is less than a predetermined amount of fluid in the drip chamber, wherein the seat includes one or more fluid passageways providing access to the lower surface of the float such that the fluid in the drip chamber can contact a sufficient portion of the lower surface of the float to allow the buoyancy of the float to cause separation between the float and the seat when there is more than a predetermined amount of fluid in the drip chamber to allow the fluid to flow from the drip chamber into the outlet of the burette.