Serum/plasma separator cannula fluid by-pass type centrifugal valve cannula seal

Claim 1

A self-contained fluid separator assembly capable of separating blood into its component phases of plasma and serum, the light phase, and cellular material, the heavy phase, comprising: a container having a first open end which is adapted to receive blood for subsequent separation into a light phase and a heavy phase and a second open end for removing the separated light phase; closures sealing the open ends of the container, the closures being formed of a self-sealing elastomeric material which is penetrable by a cannula; a piston slidably mounted in said container, having a specific gravity greater than the specific gravity of the blood and having means on an outer surface in sealing engagement with an inner surface of the container, said piston having a diaphragm portion forming partial upper and lower surfaces of said piston, said diaphragm portion being of a self-sealing elastomeric material penetrable by a cannula; said piston being disposed in said container so as to separate the chamber defined by said container with said closures, into upper and lower compartments; said piston being initially mounted in said container at a position adjacent to said second end and being constructed and arranged to move at a predetermined centrifugal force to a second position within said container, whereby said upper compartment is expanded in volume and said lower compartment is reduced in volume; a tube of pre-determined length having one end fixed to the closure for said second end and one end free, terminating within said chamber, said tube having an opening into said chamber at the terminal free end and an opening into said upper compartment at the fixed end; centrifugal valve means normally closing said opening at the terminal, free end of said tube and constructed and arranged to open under said predetermined centrifugal force; and said piston in its initial position cooperating with said tube, so that said tube pierces the diaphragm portion of said piston, whereby said tube together with said valve means forms a closed conduit through said piston, and whereby upon opening of said valve means by centrifugal force, communication between said upper and lower compartments is established, said piston in its second position being removed from cooperation with said tube, whereby said conduit is terminated and the diaphragm portion of said piston previously pierced by said tube is self-sealed.