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).

Abstract: An infusion pump pressure monitor comprises a drive (26, 27, 30, 31) for an infusion pump, a pressure sensor (38) to monitor the delivery pressure downstream of the pump, and a programmed computer (34, 35). The computer (34, 35) is programmed to monitor the maximum delivery pressure that occurs during an initial operating period, and then, subsequently to monitor the delivery pressure downstream of the pump for the remainder of the delivery period of the infusion pump. The programmed computer (34, 35) is programmed to disable the drive (26, 27, 30, 31) for the infusion pump if the monitored delivery pressure differs by more than a predetermined amount from the maximum pressure monitored during the initial operating period. The infusion liquid is carried by a disposable infusion set having a pressure responsive chamber (1) located in a key-hole shaped slot (44) in the pressure monitor.