Baxter Travenol Laboratories, Inc.

John E Gupton

Norman Shim

A system for use in flow metering apparatus for detecting bubble formation in both clear and opaque fluids in an administration set includes a light source and a light detector positioned on opposite sides of a transparent tubing segment of the administration set such that light transmitted through the tubing to the detector is dependent on the presence or absence of fluid in the tubing. With clear fluid present, a first comparator in the system interrupts operation of the metering apparatus when the light detector output falls below a predetermined minimum level. With opaque fluid present, a second comparator interrupts operation of the apparatus when the light detector output rises above a predetermined maximum level. The detection system is automatically conditioned to either clear or opaque operating modes without input from the operator, and incorporates protection circuitry for interrupting operation of the metering apparatus in the event of failure of either the light source or the light detector.

System for detecting bubble formation in clear and opaque fluids

In a flow metering apparatus, a bubble detector for detecting bubble formation in tubing includes a light source and first and second light detectors. The first light detector is positioned on the opposite side of the tubing from the light source such that the light transmitted through the tubing to the detector is dependent on the focusing effect of fluid in the lumen of the tubing. A control circuit responsive to the output of the detector interrupts operation of the metering apparatus when the light transmitted through the tubing falls below a predetermined minimum level. The second light detector is positioned at an angle to the light path between the light source and the first detector so as to receive increased light from the light source in the absence of the focusing effect of fluid in the tubing. Intensity control means responsive to the output of the light source with increased incident light at the second detector to increase the responsiveness of the bubble detector to the absence of fluid in the tubing.

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Vernon Hills, IL, United States of America

John E Gupton