Control Valves

 Control valves



  Mechanical devices used to control the flow of a fluid through a pipe.

  Fluids like

  •  Water
  • Air
  • Gas 
  • Steam

Control valve Structure




Control Valve Classification

Valves can be classified according to:

1- Valve motion (Movement of the closing element ).

(closing element ).

A- Linear motion (Slide Stem up and down )

•        Gate



•        Globe



•        Diaphragm


 

B- Rotary motion (Rotates 90°) (Quarter-turn)

 Rotates 90° from open to the close (Quarter-turn).

  Butterfly valve



  Plug valve



  Ball valve.

 


2- Valve function.

  ON /OFF Fully open Fully close (Isolation) to Isolate parts of a network for maintenance.

Throttling (Regulating ) Continuous control valve by opening % )

  Check valve/Non return valve (Prevent reverse flow)



  Safety valve (Pressure relief valve).



3- Valve end connection.



   Butt Weld Valve End Connections 

  Socket Weld Valve End Connections

  Flanged Valve End Connections.

Threaded Valve End Connections 

4- Operating method.

  Manual (hand wheel is directly connected to the stem ).



  Pneumatic (Pneumatic pressure).



  Hydraulic (Hydraulic pressure).



  Motorized  (Electrical motor).



  Solenoid (Electromagnetic force )

 


How to select your valve?

  1- What is the fluid will pass through it?

      Water , Sea water , oil ,gas or heavy oil.

  2- What is the valve suppose to do?

      Two position (ON/OFF)- throttling (flow or pressure control)

  3- What is the control valve type?

        Gate valve -  Globe valve …..

 4-What is the maximum pressure will handle with?

      Body pressure (Pressure nominal ).

   5-What is the max pressure drop will deal with?

     Close-off pressure/ shut-off.

    6-What is the critical flow factor should be?

    Cavitation or flashing possibility avoid.

 

 P&ID Valves symbols 



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