Pneumatic Control Valve Symbol

A close study of most air logic control circuits will reveal that there are only six basic valve functions commonly used.

Pneumatic control valve symbol.

Symbols identification and other circuit symbols. The symbol depicts a non return or check valve which restricts the air supply so that it air is restricted in one direction and free flowing in the other direction. An engineer may also include specific details below the control valve symbol. Most control valves however have four ports shown in hydraulic and pneumatic forms in figure 4 1.

Symbols show the methods of actuation the number of positions the flow paths and the number of ports. Bidirectional flow control bidirectional control valve symbols are the same as unidirectional but without the check valve indicating that the air is restricted in either direction. Pneumatic circuit symbols representing these valves provide detailed information about the valve they represent. Symbol description a position 2 wav s way 4 way 2 position 4 way way pot.

In the pneumatic valve return air is vented from port r. 5 3 way single pilot pneumatic valve pneumatically actuated in both directions spring centred exhausted in mid position 1 2 3 4. Pneumatic symbols directional control valves process valves description image description image 2 2 way valve air operated nc angle valve 2 way 2 2 way valve direct operated nc ball valve 2 way 2 2 way valve pilot operated nc ball valve 3 way l 3 2 way valve air operated nc ball valve 3 way t. These details may include the size function pressure rating and connection type of the valve.

In the hydraulic valve fluid is returned to the tank from port t. These six basic valve symbols when combined with the basic actuator symbols comprise virtually all the directional valve symbols needed for air logic control. For example the note 2 300 rf pb indicates that the p id calls for this valve to be a 2 ansi 300 raised face piston balanced valve. In both the load is connected to ports labeled a b and the pressure supply from pump or compressor to port p.

Directional air control valves are the building blocks of pneumatic control. The symbols for these valve functions are shown in left graphic.