Automatic Control Valves-Their Types and Function
A valve is a mechanical device used to control the flow of fluids. There are two basic types of valves, an on-off valve that stops or allows the flow of fluid and a control valve that regulates the flow of fluids. Both types of valves are used in industrial and domestic applications. Valves open and close in response to variations in pressure, level, flow, or temperature in an industrial environment. Valves function by obstructing a passageway in piping by actuation of a ball, disc, or a plug. The actuating may be accomplished manually or may be automatic. Manual valves are manually operated valves . Manual actuation entails physical contact with a handwheel, lever, or gearbox operator. On the other hand, automated actuation uses air pressure, hydraulic pressure, or electricity. The working of these valves also depends on the flow of the fluid being controlled. Some actuators remotely indicate the position of the valve opening. Pneumatically operated valves are widely used for...