Detailed Product Description

A valve is a device that regulates the flow of a fluid (, fluidized , slurries, or ) by opening,closing, or partially obstructing various passageways. Valves are technicallypipe , but are usually discussedseparately.

Valves are also found in the human body. For example there are severalwhich control the flow of blood in the chambers of the heart and maintain thecorrect pumping action (see ).

Valves are used in a variety of applications including ,,commercial, residential, and .

Oil and gas, power generation, mining, water reticulation, sewerage andchemical manufacturing would constitute the majority of valves used byindustry.

valves are the most obvious in everyday life, taps for hot and cold water, gascontrol valves on cookers and , small valves fitted to washing machines anddishwashers, and safety devices fitted to hot water systems are all examples ofvalves.

Valves may be operated manually, either by a hand wheel, lever or pedal.Valves may also be automatic, driven by changes in pressure, temperature orflow. These changes may act upon a diaphram or a piston which in turn activatesthe valve, examples of this type of valve found commonly are safety valvesfitted to hot water systems or steam boilers.

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

Valves are also found in the (internal combustion) driven by a ,lifters and or push rods where they play a major role in engine cycle control.

A huge variety ofvalves is available and has infinite applications with sizes ranging from.004" (0.1 mm) to 24" (600 mm). Special valves can bemanufactured to be in excess of 200" (5000 mm) diameter.

Valves range frominexpensive, simple, disposable valves to items in exotic materials that insome instances cost thousands of dollars (US$) per inch (25 mm) ofdiameter. These items would only be used on specialized extreme applications.

Disposable valves maybe found inside common household items including liquid or gel mini-pumpdispensers and aerosol spray cans.

Valves can becategorized into the following design types and although there are hundreds ofvariations they all fit into these basic types:

• Gate
• Poppet
• Plug
• Globe
• Check
• Butterfly
• Diaphragm
• Ball
• Needle

Valves may beclassified by how they are operated:

• manual
• Solenoid
• Hydraulic/Pneumatic