Abstract: A perfusion system incorporating a sealed reservoir in communication with a pump which allows any negative pressure at the suction inlet of the pump to be communicated into the reservoir and thereby communicated to any lines connected to the sealed reservoir. The sealed reservoir provides filtration and defoaming elements. An oxygenator and a heat exchanger may be connected to the outlet of the pump to prepare the blood for return to the patient. A control system which operates clamps and displays pressure, temperature, fluid level, and other information measured at various points in the perfusion system, is utilized with a perfusion system. In another embodiment, a hard-shell reservoir utilizing an outlet located at the bottom of the reservoir, said outlet having integral to that outlet a floating ball valve, to where the valve will be opened if there is fluid in the reservoir and closed if no fluid exists in the reservoir.