Douglas Andrew Richmond, 46Sandpoint, ID

4946448, Aug 7, 1990

Oct 23, 1989

7/425792

Douglas S. Richmond - Mission Viejo CA

Kendall McGaw Laboratories, Inc. - Irvine CA

A61M 500

604247

A medical liquid administration set is provided with a check valve which is configured to relieve excess pressure downstream from the check valve. The check valve includes a resilient valve disc and a valve seat, which engages the disc when the valve is closed. The administration set includes primary and secondary liquid sources connected through a Y-connector to a pump, which pumps liquids sequentially from the first and second sources to a patient. The check valve is disposed in the set between the Y-connector and the primary liquid source and is in its closed position with the valve disc on the valve seat when the liquid level in the secondary liquid source is higher than the liquid level in the primary source to thereby prevent backflow of liquid from the secondary source into the primary. The check valve is in its open position, allowing flow from the primary source to the patient when the liquid level in the secondary source has fallen to the level of liquid in the primary source. The valve disc is of a resilient material, and a slit is through the disc so that when the downstream pressure is greater than the upstream pressure by a selected value, the slit is forced open to relieve the excessive pressure.