Valve is a mechanical device used to control the flow direction of the fluid (liquid, solids, gases, fluidizers, slurries) and pressure in a system. In the open valves system the direction of the fluid is always passes from high pressure to low pressure.



The pressure flow and fluid flow mainly depends on the following functions

  • Starting and stopping flow of the liquid
  • The flow of the fluid is varying
  • Controlling the flow direction of the fluid
  • Regulating the pressure process and downstream
  • Due to over pressure the piping components are relieving

Symbol of valve


Uses of valves:

  • Valves are used to control the fluid from flooding.
  • Flow controlling process used in industries, residential used for ‘ON’ or ‘OFF’ pressure controls in homes.
  • Spray can also consist of small valve manufactured inside.
  • Valves are used in the transport and military regions/zones.
  • We can see the valves in the industrial process like gas and petroleum, chemical and plastic, food manufacturing, mining, oil processing, power generation etc.
  • In many developed countries valves are used in the daily purpose like dishwashers, laundry equipment, gas control devices, drains valves, taps, hot water system, poppet valves in engine.

Selection of value

Based upon certain factors the values are selected they are:

  • Pressure of the fluid
  • Temperature carried out by the fluid
  • Type of fluid (gases, liquids, solids, corrosive, dirty or abrasives),
  • Flow condition (velocity, pressure drop, back flow, on or off valve),
  • Operation condition (size and space available, manual or automated control, accessibility, fire safe design, joints leaks, speed of closure)

Types of valves

  • Valves are divided in to several types they are:
  • Check valve
  • Hydraulic valve
  • Pneumatic valve
  • Manual valve
  • Solenoid valve
  • Motor valve

Check valves:

Check valves are the ancient type of valves. By using the check valves we can send the fluid in a single direction itself. It consists of two openings in the body one is used for input of the fluid and the other is used for the fluid output. Check valves are also divided in to 8 types they are:

  • Ball check valves
  • Diaphragm check valves
  • Swing check valves or tilting disc check valves
  • Stop check valves
  • Lift check valve
  • In line check valve
  • Duck bill valve
  • Pneumatic non return valve


Hydraulic valve

Hydraulic valve is an electro – mechanical or mechanical device used to control the flow of the fluid in the hydraulic fluid system. The hydraulic drives are operated with the help of hand in the mobile system and activated electrically in the fixed system. At the time of manufacturing process it includes the specifications like pressure rate, actuator type, number of ports, configuration of the ports, valve type, connections of port, material used for construction.


Types of hydraulic valves

  • Directional control valves
  • Pressure control valves
  • Flow control valve
  • Electro hydraulic valve

Advantages of hydraulic valve

  • Supplied energy does not transfer the liquid
  • Due to incompressibility the hydraulic drive provides high forces and also having the capability of bearing high loads.
  • Incompressibility of the working fluid leads to the minimum spring action
  • The flow of the fluid is stopped at that case the load pressure is released
  • Pressurized air is used to release the pressure load.

Pneumatic valve

Pneumatic valves are responsible for the air intake and pressure rate in the pneumatic system. Power is transmitted when the force is applied on the air or compressed with the air accordingly. Different types of the pneumatic valves are used in the device.

Symbol of pneumatic valve


Pneumatic valves are divided in to 5 types

  • Two way directional valve
  • Three way directional valve
  • Four way directional valve
  • Spring offset
  • Two way directional spring off set


Advantages of pneumatic valves:

  • Design of the pneumatic value is simple and easy to control
  • Maintenance is less compared to others
  • We can see long operating lives
  • Shock damage is less in the equipment because of gas compression

Solenoid valve

Electro mechanical operated value is present in the solenoid valve. The valve is controlled with the help of electric current. The value consists of two port and three port flow.

  • We can see ‘ON’ and ‘OFF’ conditions of the fluid flow in the two port valve
  • In the three port valve the flow of the fluid is exchanged between the two outlet ports.

Solenoid valves are commonly used control components in fluidics. They are used to release, shut off, mix fluids, distributes the fluids.

Symbol of Solenoid valve



Solenoid force:


Types of solenoid valves:

  • Alternate current or direct current
  • One or two solenoid valves
  • Different number of position and ways


They provide safe and fast interchanging, long service life, good compatibility, compact design; power control must be low, high reliability and long service life.

Different types of valves used are

Aerosol valves, air logic valves, balancing valves, ball valves, blind valves. Butterfly valves, cartridge valves, casing valves, Christmas tree valves, cock valves, control valves, diaphragm valves, dis valves, faucet valves, gate valves, globe valves, hydraulic valves, needle valves, pinch valves, piston valves, plug valves, poppet valves, relief valves, rotary valves.

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