Importance

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Abstract

Disposable pump cassette for a liquid comprising a substantially rigid housing providing a chamber and having upper and lower portions. A flexible substantially cylindrical bladder is vertically disposed in the chamber and has an inlet adapted to receive the liquid and an outlet. The bladder has upper and lower wall portions. The lower wall portion is of a thinner cross section then the upper wall portion. An inlet valve is disposed in the inlet of the bladder and is mounted in the lower portion of the housing. An outlet valve is disposed in the outlet of the bladder and is mounted in the upper portion of the housing. The inlet and outlet valves are disposed in the liquid and provide unidirectional flow of the liquid through the bladder. A substantially incompressible driving liquid is disposed in the chamber and surrounds the bladder. A housing extension is mounted on said housing and is in communication with the driving liquid disposed in the chamber. A movable piston is slidably mounted in the housing extension. A drive is provided for reciprocating the piston for causing displacement of the driving liquid in the chamber to compress and decompress the bladder to cause the liquid to flow through the bladder progressively from the lower portion to the upper portion of the bladder.

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First Claim