System for detecting bubble formation in clear and opaque fluids

摘要

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.