Valves are defined as device to control or regulate the direction,flow and pressure of a fluid
Valve available for pneumatic control can be classified into four principal groups according to their function
1.Direction control valve
2.Non return valves
3.Flow control valve
4.Pressure control valve
Directional control valve
A valve is a device that receives an external signal to release,stop or redirect the fluid that flows through it.
The function of a DCV is to control the direction of air flow in any pneumatic system.A DCV does this by changing the position of internal movable parts.
To be more specific,a DCV is mainly required for the following purposes
Directional control valves are used to start,stop and direct the flow of air in pneumatic system.
By directing the flow of air,these valves controls the action of other pneumatic devices,such as cylinders,motors,pumps or other valves.
To permit the free flow from the pump to the reservoir at low pressure when the pump’s delivery is not needed into the system
To vent the relief valve by either electrical or mechanical control
To isolate certain branch of a circuit
Classification of Directional Control Valves
Directional control valves can be classified in the following manner
1.Type of construction
Poppet valve or seat valve
Spool valves a)Sliding spool b)Rotary spool
2.Number of ports
Two way valve
Three way valve
Four way valve
3.Number of switching position
- Actuating mechanism
Manual actuation - Manual actuators are hand lever,push buttons and pedals etc
Mechanical actuation -