Editing Valve (section)

==Applications==
Valves are found in virtually every industrial process, including water and sewage processing, mining, power generation, processing of oil, gas and petroleum, food manufacturing, chemical and plastic manufacturing and many other fields.

People in developed nations use valves in their daily lives, including [[plumbing]] valves, such as [[tap (valve)|tap]]s for [[tap water]], gas control valves on cookers, small valves fitted to [[washing machine]]s and [[dishwasher]]s, safety devices fitted to [[Water heating|hot water system]]s, and [[poppet valve]]s in car engines.

In nature, there are valves, for example one-way valves in [[vein]]s controlling the [[Circulatory system|blood circulation]], and heart valves controlling the flow of blood in the [[chambers of the heart]] and maintaining the correct [[pump]]ing action.

Valves may be operated manually, either by a handle or grip, [[lever]], pedal or wheel. Valves may also be automatic, driven by changes in pressure, [[temperature]], or flow. These changes may act upon a [[Diaphragm (mechanical device)|diaphragm]] or a [[piston]] which in turn activates the valve, examples of this type of valve found commonly are [[safety valve]]s fitted to hot water systems or [[boiler]]s.

More complex control systems using valves requiring automatic control based on an external input (i.e., regulating flow through a pipe to a changing set point) require an [[actuator]]. An actuator will stroke the valve depending on its input and set-up, allowing the valve to be positioned accurately, and allowing control over a variety of requirements.