chapter  91
PID Control
Pages 10

Process control plays an essential role in the safe manufacture of quality products at market demand while protecting the environment. Flow rates, pressures, and temperatures within pipes and vessels, inventories of liquids and solids, and product quality are all examples of measured variables that must be controlled to meet the above objectives. While there are several means available for controlling these variables, the proportional-integral-derivative (PID) family of controllers has historically carried the major share of this responsibility and, because of their simplicity and reliability, will continue to do so in the future.