Businesses in the process control equipment sector supply, configure and maintain instruments and systems used to monitor and regulate industrial processes. Equipment can measure variables such as temperature, pressure, flow, level, humidity and chemical composition, helping operators keep production within specified limits. Typical products include sensors, gauges, transmitters, process controllers, programmable logic controllers, control valves, actuators and industrial measurement analysers. Some businesses also design or integrate control systems, including operator interfaces and supervisory software, so equipment can be monitored and adjusted centrally or automatically. Services may include selecting and installing instruments, connecting them to existing plant systems, commissioning, calibration, fault diagnosis, repairs and planned maintenance.