ABSTRACT
The term “control” is used in the process industry to describe the regulation of all aspects of a process. A number of process applications require precise control of levels, temperatures, pressures, and flows. In order to produce profitable end products, fluids must be refined, combined, handled, and manipulated in a complex, precise, and potentially hazardous manner. Processes are controlled for three primary reasons: to reduce variability, to increase efficiency, and to ensure safety. Modern processing plants use numerous control loops in order to manufacture and deliver their products. Several terms and concepts related to process control are discussed in this chapter, including process variables, setpoints, and error. This chapter also provides an overview of some sensors and instruments such as pressure, temperature, and flow gauges.
