The application of fleuric devices to gas chromatographic instrumentation

This chapter concerns the application of fleuric devices in gas chromatographic instrumentation. It discusses the use of these devices as sampling valves, detectors, logic gates, and, finally, as transducers in optical-to-pneumatic conversion elements of nonelectrical process control chromatographs. The chapter reviews briefly the principles governing the operation of the particular fleuric device which is germane to the application. The necessity for designing sensors to be used in environments where explosive gases may be present persists as a design restraint for chromatographs to be used in process control applications. One solution which we have favored is to eliminate electricity as a source of power and substitute a more benign source such as pressurized gas or low-pressure steam. In line with this idea, a stand-alone nonelectrical gas Chromatograph with its own on-board pneumatic computer has been commercially available for some years.