Abstract: A device for use to detect air in a fluid line between a medication infusion reservoir such as an IV bottle or bag and an IV injection set or a medication infusion pump is disclosed which utilizes a detector apparatus which clamps onto a segment of tubing. The detector uses a light source to generate light which is directed into the tubing, and two light detecting devices, one of which is used to determine whether or not the tubing is properly installed in the detector, and the other of which is used to detect the presence of air in the segment of tubing. The detector works equally well with transparent, translucent, or opaque fluids and includes means for ensuring that the detection system is functioning normally.