Valve
From Wikipedia, the free encyclopedia.

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

There are a number of names for particular type of valve:

• Cock, colloqual term for a small valve
• Tap (British english), Faucet (US english)
• Bib cock,
• Non-return valve, allows the fluid to pas in one direction only
• Ball cock, Often used as a water level controller (cistern)
• Solenoid valve, electrically controlled
• Safety valve, operates automatically to correct a potentially dangerous situation

A valve doesn't necessarily mean a man-made device; there are several valves inside the human body, for instance in the heart or in veins.

Because their effect on a flow of electrons is analogous to the fluid devices, the electronic devices known in the US as "vacuum tubes" are called "thermionic valves" in Britain.

The original article can be found at: http://en.wikipedia.org/wiki/Valve.
All text is available under the terms of the GNU Free Documentation License.