SENSOR AND METHOD FOR DETECTING THE PRESENCE OF AIR BUBBLES IN LIQUID

摘要

An air bubble sensor device comprises a sensor block (12) and a recess (16) in the block for receiving a hollow tube (15) through which liquid flows. The tube has an interior surface and an exterior surface. A light source (33) is arranged in the block to direct light at the tube when placed in the recess. This arrangement permits light rays to strike the interior surface at an angle with respect to the normal of the interior surface. A light detector (35) is arranged in the block to receive a light reflected at the interior surface when an air bubble is present in the tube. The light detector is positioned to receive substantially no light refracted at the interior surface when liquid is present in the tube. A mechanism is provided for taking the light received by the detector to produce a signal for indicating the presence of an air bubble in the tube. A method for detecting the presence of an air bubble in liquid is also within the purview of the present invention.