ABSTRACT
This chapter presents the general layout of a contemporary gas chromatograph, together with the separation flow-pattern, and the computer control pathways. There are a number of pressure controllers associated with a gas chromatograph. The reducing valves on the gas tanks are in fact simple pressure controllers and the flow controllers that are used for detector and column flow control usually involve basic pressure controllers. When there is flow, the down stream sensor is heated producing a differential temperature across the sensors. As the temperature of the gas will be proportional to the product of mass flowing and its specific heat, the differential temperature that will be proportional to the mass flow rate. A number of different sample injectors are necessary that are designed correctly for different types of sample and different column configurations. Chromatography techniques are extensively used for repetitive assays in process and product control and, consequently, many of the sample preparation procedures have been automated.
