The Online Encyclopedia and Dictionary







A valve is a mechanical device that regulates the flow of fluids (either gases, fluidised solids, slurries or liquids) by opening, closing, or partially obstructing various passageways.

Valves are used in a myriad of industrial, military, commercial, and residential applications. There are many different types of valves:

Different valves may be used for a variety of purposes:

  • A flow control valve maintains a constant flowrate through the valve.
  • A heart valve regulates blood flow through the heart in many organisms.
  • A poppet valve is commonly used in piston engines to regulate the fuel mixture intake and exhaust. The sleeve valve is another valve type used for this purpose.
  • A pressure reducing valve reduces pressure to a preset level downstream of the valve.
  • A pressure sustaining valve maintains pressure at a preset level upstream of the valve.
  • A regulator is used in SCUBA diving equipment and in gas cooking equipment to reduce the high pressure gas supply to a lower working pressure
  • A safety valve or relief valve operates automatically at a set differential pressure to correct a potentially dangerous situation, typically over-pressure.
  • A three way valve routes fluid from one direction to another.
  • Vacuum breaker valves prevent the back-siphonage of contaminated water into pressurized, potable water supplies.

Other uses of the term

See also

Last updated: 06-01-2005 21:42:50
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