A flow control valve regulates the flow or pressure of a fluid. Control valves normally respond to signals generated by independent devices such as flow meters or temperature gauges. Control valves are normally fitted with actuators and positioners. Pneumatically-actuated globe valves are widely used for control purposes in many industries, although quarter-turn types such as (modified) ball and butterfly valves are also used. For the computer software/games company, see Valve Software A valve is a device that regulates the flow of fluids (either gases, fluidised solids, slurries or liquids) by opening, closing, or partially obstructing various passageways. ... A subset of the phases of matter, fluids include liquids, gases, plasmas and, to some extent, plastic solids. ... In telecommunication, signalling (or signaling) has the following meanings: The use of signals for controlling communications. ... Flow measurement is the quantification of bulk fluid or gas movement. ... A device used to indicate the temperature of an item being monitored. ... Pneumatics, from the Greek πνευματικός (pneumatikos, coming from the wind) is the use of pressurized air in science and technology. ... schematic 3 way ball valve A ball valve (like the butterfly valve, one of a family of valves called quarter turn valves) is a valve that opens by turning a handle attached to a ball inside the valve. ... A Butterfly valve is a type of flow control device, used to make a fluid start or stop flowing through a section of pipe. ...

Control valves can also work with hydraulic actuators (also known as hydraulic pilots). These types of valves are also known as Automatic Control Valves. The hydraulic actuators will respond to changes of pressure or flow and will open/close the valve. Automatic Control Valves do not require an external power source, meaning that the fluid pressure is enough to open and close the valve. Automatic control valves include: pressure reducing valves, flow control valves, back-pressure sustaining valves, altitude valves, and relief valves. An altitude valve controls the level of a tank. The altitude valve will remain open while the tank is not full and it will close when the tanks reaches its maximum level. The opening and closing of the valve requires no external power source (electric, pneumatic, or man power), it is done automatically, hence its name. Relief Valve A relief valve opens to release excess pressure when the pressure is too high to protect the vessel or other equipment from overpressurization. ...