A valve is a device that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. In an open valve, fluid flows in a direction from higher pressure to lower pressure. Valves have many uses, including controlling water for irrigation, industrial uses for controlling processes, residential uses such as on / off & pressure control to dish and clothes washers & taps in the home. Valves are found in virtually every industrial process, including water & sewage processing, mining, power generation, processing of oil, gas & petroleum, food manufacturing, chemical & plastic manufacturing and many other fields. Valves may be operated manually, either by a handle, lever, pedal or wheel. Valves may also be automatic, driven by changes in pressure, temperature, or flow.