Abstract: A control system for sequentially communicating a source of pressurized fluid mixture to first and second beds of adsorption material to separate at least one component from the fluid mixture and produce a product fluid. A pressure transducer connected to a supply conduit develops a switching signal corresponding to a predetermined fluid pressure in the fluid mixture communicated to the first and second beds of adsorption material. An electronic controller responds to the switching signal to sequentially develop first and second electrical signals. The electronic controller allows the first and second electrical signals to overlap for a predetermined controlled time period. Valve mechanisms sequentially respond to the first and second electrical signal to prevent communication of the fluid mixture to one of the first and second chambers while allowing communication to the second chamber.

Abstract: A contact probe arranged to detect dislodgement of the probe from a body to which it has been attached. Probe dislodgement is detected by sensing an increased radiation level falling on a main sensor (14) located in the contact surface (10a) of the probe. The main sensor cooperates with a reference sensor (16) located in another surface (10b) of the probe which receives radiation reflected from the skin of the body to which the probe is attached. The reference sensor (16) provides a floating reference for the main sensor (14). In addition to providing an indication of probe dislodgement, the two sensors cooperate to develop an indication when they are shielded from the radiation source, thereby rendering the probe inoperative to sense probe dislodgement.