Process control systems are used in everything from advanced manufacturing to run-of-the-mill activities at home, like heating your house and brewing your beer. (You do brew your own beer, don't you?)
A control system that manufactures a product requires monitoring and control of many different process variables, while some at home require little more than a timer. For example, in manufacturing we may use flow meters to make sure fluids flow through pipes at a certain rate, or float meters to ensure ingredients fill a vat to a specified level.
When I brew beer at home, I may use a temperature sensor in my mash tun, wired to a controller that’s controlling my heating element to keep the mash tun at just the right temperature for optimum starch-to-sugar conversion. This is an example of a closed-loop control system.
(To see how small closed-loop control principles are scaled up to build industrial process control applications, check out the New Belgium Brewery case study and see how they use Opto 22 gear to brew their world-famous Fat Tire and other beers.)