What is valve..?

These water valves are operated by handles.

                                                       A valve is a device that regulates the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening closing or partially obstructing various passageways. Valves are Technically pipe fittings. But are usually discussed as a rate category In an open valves Fluid flows in a direction from higher pressure to lower pressure. Valves are also found in the Human body. For example, several heart valves control the flow of blood in the chambers of the heart and maintain the correct pumping action.

Valves are used in a variety of contexts, including industrial, military, commercial Residential, and transportation. The industries in which the majority of valves are used are oil and gas. Power generation, mining, water reticulation. Sewerage and Chemical Manufacturing.Plumbing valves, such as taps for hot and cold tap water are the most Noticeable types of valves. Other valves encountered daily include gas control valves on cookers, small valves fitted to washing machines and dishwashers, and safety devices fitted to hot water systems.

Valves may be operated manually, either by a hand wheel, lever or pedal. Valves may also be automatic. Driven by changes in pressure, temperature, or flow. These changes may act upon a diaphragm or a piston which in turn activates the valve, examples of this type of valve found commonly are safety valves fitted to hot water systems or boilers.

More complex control systems using valves requiring automatic control based on an External input (i.c regulating flow through a pipe to a changing set, point requires an actuator.

An actuator will stroke the valve depending on its input and set-up, allowing the valve to Positioned accurately and allowing control over a a variety of requirements. Valves are Also found in the Otto cycle (internal combustion) engines are driven by a camshaft, tappet or Pash rods where they play a a major role in engine cycle control.

APPLICATIONS:

• Valves vary widely in form and application Sizes typically range from 0.1 mm 60 cm (2 ft). Special valves can have a diameter exceeding 5 meters.
• Valve cost ranges from simple inexpensive disposable valves to specialized valves Cost thousands of US dollars per inch of diameter.

• Disposable valves maybe found inside common household items including mini-pump dispensers and aerosol cans

TYPES:

The inside of an extremely large butterfly valve

Valves are quite diverse and may be classified into a number of basic types. Valves may So be classified by how they are actuated:

• Hydraulic
• Pneumatic
• Manual
• Solenoid
• Motor

BASIC TYPES:

valves can be categorized into the following basic types:

 

DUPLEX BALL VALVE

• The ball valve, for on/off control without pressure drop, and ideal for quick shut-off since a 90° turn offers complete shut-off angle, compared to multiple turns required on most Manual valves

• Butterfly valve, for flow regulation in large pipe diameters.

• Choke valve, a valve that raises or lowers a solid cylinder which is placed around or inside another cylinder which has holes or slots. Used for high-pressure drops found in oil and gas wellheads

• Check valve or non-return valve, allows the fluid to pass in one direction only

HASTELLOY CHECK VALVE

·         Diaphragm valve, some are sanitary predominantly used in the pharmaceutical and Foodstuff industry.

·         Ceramic Disc valve, used mainly in high duty cycle applications or on abrasive fluids Ceramic disc can also provide Class IV seat leakage

·         Gate valve, mainly for on/off control with low pressure drop.

STAINLESS STEEL GATE VALVE

     

·         Globe valve, good for regulating the flow

·         Knife valve, for slurries or powders on/off control.

·         Needle valve for accurate flow control.

·         Piston valve, for regulating fluids that carry solids in suspension

·         Pinch valve, for slurry flow regulation.

·         Plug valve, slim valve for on/off control but with some pressure drop.

·         Spool valve, for hydraulic control

·         Thermal expansion valve, used in refrigeration and air conditioning systems.

·         Poppet valve