Level Control Valve loose feedback linkage causing an unstable level

Описание: A control valve is a valve used to control fluid flow by varying the size of the flow passage as directed by a signal from a controller. This enables the direct control of flow rate and the consequential control of process quantities such as pressure, temperature, and liquid level.

In automatic control terminology, a control valve is termed a "final control element".

Pneumatic valves play an important role in a pneumatic system. They determine how much air passes through and in which direction. This means that they can be used as control valves, but also as safety valves that shut off the air supply in dangerous situations or that depressurise the system.