Other analytical instruments perform continuous analyses of a process stream for a specific parameter such as oxygen content, gas density, etc.
Some continuous analyzers pump or flow a sample through a detector cell. Others place the detector element directly in the process stream. The methods of detection vary widely and may include the use of nuclear radiation, optics, vibrating reeds, flotation cells, catalytic “burners,” and other methods.
Fig. 4-39 shows a typical block diagram for a process chromatograph installation. Fig. 4-40 identifies several types of continuous process analytical instruments and a type of detection used by each.