Importance

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Abstract

An air-in-line detector for detecting the presence of air in a translucent tube (8) containing a liquid comprises a channel (18) for receiving the tube, only three radiation emitter detector pairs (11, 12; 13, 14; 15, 16) two of which (11, 12; 15, 16) are arranged to detect the presence of an opaque liquid with the emitter (11, 15) and detector (12, 16) of each pair being located on opposite sides of the channel (18) so that radiation emitted by the radiation emitters impinges directly on their associated detectors and one (13, 14) of which is arranged to detect the presence of translucent liquids with its emitter (13) and detector (14) being located on opposite sides of the channel (18) but not directly aligned so that radiation emitted by the radiation emitter (13) only impinges on its associated detector (14) after refraction by the tube (8) filled with a translucent liquid, and a programmed computer (1). The computer (1) is coupled to the emitters and detectors and is programmed to monitor their outputs and to give an indication indicating the presence of air in the tube (8) except when the outputs of all three detectors (12, 14, 16) show that none of them are receiving radiation from the associated emitters (11, 13, 15) or that all of them (12, 14, 16) are receiving radiation from their emitters (11, 13, 15) but no longer continue to do so when the emitter (13) of the translucent liquid emitter-detector pair (13, 14) is turned off.

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First Claim