Process heating valves are automated with a number of technologies used to drive the movement of the valve — electric, pneumatic and hydraulic actuation, for instance. These operators normally have both automated and manual modes of operation. When it is necessary for valve or actuator maintenance such as when doing periodic valve calibration, the operations and maintenance team (O&M) must be in close communication to ensure that the valve can be safely moved without harm to the people, equipment and processes that are being controlled.
In the past, this has been done with one operator in the control room looking at the supervisory software (SCADA) screens. He or she would ensure that the reported position of the valve and the position of other interrelated valves are as planned. He or she would also check that temperatures and pressure measurements around the valve are conducive to the intended maintenance procedure. In this environment, communication to the maintenance worker at the valve is often done using radios.