| abstract |
The flow controller repeatedly opens and closes a magnetic check valve for periods of time which determine the flow rate through the valve. The magnetic valve preferably has a movable valve closure member with an elongated stem which extends parallel to the direction of flow of fluid through the check valve. The stem is made of magnetic material. An electro-magnet is placed at the side of the valve, outside of the valve housing. The electromagnetic field pulls the valve stem laterally to tip the valve member and open the valve. When the magnet is de-energized, the valve member moves back to its seat. The controller is used to control the flow of parenteral fluids into the veins of a human patient. The parenteral fluid controller has a drip chamber for collecting drops of fluid falling from a reservoir. The magnetic check valve is located in the conduit between the drip chamber and the patient''s vein. A drop detector is provided for producing a signal each time a drop is formed. The latter signal controls the opening and closing of the valve and thus controls the flow of the parenteral fluid. Safety features are provided whereby the valve closes automatically if a drop has not been detected for a pre-determined length of time. Therefore, abnormalities in the operation of the system will not cause excessive flow of Fluid or infusion of air into the patient''s veins. An attendant will be warned of such a condition, or if the flow rate is too low or too high, or if the fluid level in the reservoir is low. |