Abstract: An infusion pump system is described containing a valved cassette which is used as a pumping chamber for conducting fluid from an upstream portion to a downstream portion of the system. The removable cassette contains magnetically biased valves at both ends. Externally mounted magnets bias the valves within the cassette to provide an opening of the inlet valve and closing of the output valve during the fill cycle and closing of the inlet valve and opening of the outlet valve during the pump cycle. Free flow of infusion fluid is allowed when the valved cassette is removed from the pump mounting member which houses the actuating magnets and the reciprocating actuator for the pumping chamber.

Abstract: A device for measuring the volume of flow in a liquid conveying apparatus wherein drops of the liquid are formed and directed into a length of measurement tubing having a known internal diameter. As the drop is passed through the measurement tubing its length is determined by a combined optoelectronic mechanism including drop length sensors. The drop forming portion and measurement tubing can be manufactured from inexpensive resinous materials making these portions disposable and particularly adaptable to intravenous administration.

Abstract: A device for measuring the volume of flow in a liquid conveying apparatus wherein the length and velocity of a liquid column are measured. Drops of the liquid are formed and directed into a length of measurement tubing having a known internal diameter. As the liquid column is passed through the measurement tubing its length is determined by two spaced apart liquid sensors. The actual length is determined by calculating the time elapsed for the leading edge of the liquid column to interrupt the two liquid sensors. The time for the trailing edge to pass the first sensor is proportioned to the length of the column and the quotient of the two values will give the actual length. Accordingly, accurate volume determinations can be made irrespective of velocity change such as due to viscosity, surface tension or back pressure. The device of this invention is especially adapted to be used in conjunction with an intravenous administration set.

Abstract: An I.V. administration set is provided with a flexible expansion section so as to accommodate an additional volume of liquid without the use of excessive lengths of tubing. The expansion section is in the form of pleated or corrugated tubing which, upon the introduction of liquid into an I.V. set such as by means of a hypodermic syringe, will accommodate an additional portion of liquid which is known in the I.V. administration art as a retrograde volume.