Abstract: A piston pump propels liquid through a lumen of a flexible tube segment. The pump includes a first tube clamping member, a first set of tube squeezing members, a second tube clamping member, a second set of tube squeezing members and a synchronizing arrangement for activating the members in a sequential order such that fluid in the tube is displaced in a downstream direction.

Abstract: The valve assembly has inlet and outlet members with valve elements disposed between the two members. The valve is a resilient membrane having one or more through holes. When there is no pressure differential across the valve, the hole walls in the membrane collapse inwards closing off the valve against liquid flow. At or above a threshold pressure differential across the valve, the membrane is stretched which opens up the hole or holes to allow the passage of liquid.

Abstract: A peristaltic pump for propelling liquid through a flexible tube segment. The pump has a cam shaft which carries a plurality of cams each having a driving surface. The driving surfaces of adjacent cams are spaced at an angle to each other about the cam shaft. The pump also has a plurality of cam followers which are each reciprocal in a common direction perpendicular to the axis of the cam shaft. Each cam follower has a cam surface riding on the driving surface of a cam and a tube engaging surface for engaging the flexible tube segment. At least one of the cam followers is a restriction cam follower of which the tube engaging surface engages the flexible tube segment for a longer period than that of the other cam followers. The pump also has a motor for rotating the cam shaft whereby the cams cause the cam followers to each engage and occlude the flexible tube segment to form a propagating depression wave in the flexible tube segment for propelling liquid.

Abstract: A flow set which enables the sequential administration of two liquids from a pair of containers to a patient. The flow set has a pair of valve assemblies each in communication with a container. Each valve assembly has three ports communicating through a communication chamber; an inlet port being sealed with a first one-way valve allowing flow of liquid through it only into the chamber, an outlet port being sealed with a second one-way valve allowing flow of liquid through it only out of the chamber, and a pump communication port. A pair of inlet tubing segments each connect a container to the inlet port of a valve assembly. A connecting tubing segment connects the pump communicating ports of the two valve assemblies. An outlet tubing segment connects to the outlet port of each valve assembly for delivery of the liquid to the patient. A pump is connected to the connecting tubing segment. By reversing the pumping direction of the pump, liquid may be sequentially draw from one container or the other.

Abstract: A flow set which enables the sequential administration of two liquids from a pair of containers to a patient. The flow set has a pair of valve assemblies each in communication with a container. Each valve assembly has three ports communicating through a communication chamber; an inlet port being sealed with a first one-way valve allowing flow of liquid through it only into the chamber, an outlet port being sealed with a second one-way valve allowing flow of liquid through it only out of the chamber, and a pump communication port. A pair of inlet tubing segments each connect a container to the inlet port of a valve assembly. A connecting tubing segment connects the pump communicating ports of the two valve assemblies. An outlet tubing segment connects to the outlet port of each valve assembly for delivery of the liquid to the patient. A pump is connected to the connecting tubing segment. By reversing the pumping direction of the pump, liquid may be sequentially draw from one container or the other.

Abstract: A pump for delivering a liquid from a container to a patient through a flow set. The pump includes a sensing means and a controller. The sensing means senses a parameter indicative of the pressure in the flow set. The controller has a computing and memory means for determining deviation of the parameter from a standard. Deviation is indicative of an error in the flow set. This enables supervising staff to be alerted. These errors may be incorrect assembly of the system or one of its components, inclusion in the system of an incorrect valve, impairment in the integrity of the flow set, and the existence of air bubbles in the system.

Abstract: Medical infusion apparatus includes a container for a liquid to be infused, tubing leading from the container to the subject to receive an infusion, a pump for pumping the infusion liquid via the tubing to the subject, and a safety valve connected in the tubing between the pump and the subject. The safety valve is normally closed to prevent free-flow of the liquid from the container, but is automatically opened when a predetermined minimum pressure is applied to the liquid by the pump. The safety valve is also manually deformable to open the valve and to permit priming the apparatus.