Process Control In order to produce a product with consistently high quality, tight process control is necessary. A simple-to-understand example of process control would be the supply of water to a number of cleaning stations, where the water temperature needs to be kept constant in spite of the demand. A simple control block is shown in Fig. 1.1a, steam, and cold water are fed into a heat exchanger, where heat from the steam is used to bring the cold water to the required working temperature.