Valve
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: Ball cock, often used as a water level controller (cistern); Ball valve, which is good for on/off control; Bibcock; Butterfly valve, particularly in large pipes; Cock, colloquial term for a small valve; Gate valve, mainly for on/off control; Globe valve, which is good for regulating flow; Hydraulic valve (diaphragm valve); check valve or Non-return valve, allows the fluid to pass in one direction only; Pilot valves regulate flow or pressure to other valves; Plug Valve, for on/off control; Solenoid valve, an electrically controlled hydraulic or pneumatic valve; Tap (British English), Faucet (American English) is the common name for a valve used in homes to regulate water flow; Rotary valves and piston valves are parts of brass instruments used to change their pitch. 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 - in electronics, a valve (British English) = vacuum tube (American English)
See also - Valve Software
- Plumbing
- Backwater valves
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