Umesh Chikhale

1. HYDRAULIC AND PNEUMATIC CONTROL
ELEMENTS

2. NECESSITY OF FLOW CONTROL VALVES
 The control of fluid dynamics is essential to ensure efficient,
reliable and safe operation of pumping systems. A pump
puts fluid in motion by adding energy to it.
 This kinetic energy, observed as pressure, is carried in the
fluid and slowly lost to friction in the piping system.
 Uncontrolled fluid in motion can physically destroy the
pump, piping, valves, meters and other system
components.

3. FLUID CONTROL VALVES
Pressure
Control
Valves
Flow
Control
Valves
Direction
Control
Valves
1. Pressure Relief
-Directly operated
-Pilot operated
2. Counter balance
3. Pressure reducing
4. Sequencing valves
1. Non compensated
Flow Control valve
2. Pressure compensated
flow Control valve
3.Temp. compensated
flow Control valve
1. 2/2, 3/2, 4/3 valves
2. Manually operated
3.Solenoid operated
4. Pilot operated
5. Cartridge valves
6. Check Valves
- Directly operated
- Pilot operated
Method of actuation
1. Directly operated
2. Pilot operated
3. Manually operated
4. Electrically operated

4. PRESSURE CONTROL VALVES
1. Pressure Relief Valve
- Directly operated
- Pilot operated
2. Pressure Control Valve
3. Sequence Valve

5. 1. PRESSURE RELIEF VALVE
-This valve used to limits the pressure in the whole system.
-Also called as Safety valve or Maximum Pressure valve.
-Pressure relief valve is normally closed type valve.
-It is located between the Pump and direction control valve (Before the actuator)
Directly operated

6. Pilot operated

7. PRESSURE REDUCING VALVE
Directly operated
- Pressure reducing valve is used to maintain pressure in second
branch of the system.
Main Branch
P1
Second Branch
P2

8. SEQUENCE VALVE
 The sequence valve is used to supply the flow of fluid to second consumer if
requirement of first consumer is fulfilled.
 It consist of pilot relief valve.
 Also consist of two spools connected to each other.

9. COUNTER BALANCE VALVE
 This valve is used to avoid uncontrolled movement of cylinder.
 This valve is used in earth moving equipments.
 It consist of two pilot relief valves are connected to each others.
 It holds the load for some time like lifting trolley of the tractors or the
trucks.
Fluid is controlled by resisting it from one side
and free from its other side.

10. FLOW CONTROL VALVE
 Flow control valve is used to control the flow rate in the system according
to system designed.
 Flow rate is controlled by the throttling or the diverting.
 Throttling means by using the orifices, throttle valves etc. and diverting
means bypassing it to reservoir using the flow control valve.

12. NON-COMPENSATED FLOW CONTROL VALVE
 In such valves Pressure, velocity and flow rate will get varies. It will not
remain constant. The orifices, throttle valve are come in this above
valve.

14. Pressure Compensated Flow
control Valve

15. Pressure - Temperature Compensated Flow
control Valve

16. Variable Flow control Valve

17. Non return type Flow control Valve

18. CHECK VALVE OR NON-RETURN VALVE
 This valve allows the flow of fluid in only one direction bur dose not allow
flow in other direction.
 Also called as Non Return valve.
Directly operated check valve (Poppet type)

20. Pilot operated check valve (Poppet type)

21. Shuttle valve

22. Quick Exhaust Valve

23. DIRECTION CONTROL VALVE
 The Direction Control Valves are used to change the direction
of flowing fluid.
 We have required to move the actuator in the different
direction and it is actuated by supplying the fluid in different
directions using D.C.V. 2/2 DCV
Ports Positions

25. METHOD OF ACTUATIONS FOR D.C.V.

27. 2/2 DIRECTION CONTROL VALVE
•This is the 2/2 DCV which is spring operated type.
•Here both OFF and ON positions of the valve are shown in the above figures.
•If fluid is coming from pump, the spring moves towards right and port P is
connected to port A and fluid is supplied to actuator.

28. 3/2 DIRECTION CONTROL VALVE
P
A
R R
A
P
3/2 DCV symbol

29. 4/2 DIRECTION CONTROL VALVE (SPOOL TYPE)
P
A
R R
A
P
B B
4/2 DCV symbol

30. 4/3 DIRECTION CONTROL VALVE
 4/3 DCV having the 4 ports and 3 position for the actuation of it.
 In three positions this valve will be actuated.
 The symbol of this particular (4/3 DCV) valve is given below.
 According to center positions of above valve it is classified in
three types.
1. Closed Center position valve
2. Open Center position valve
3. Tandem Center position valve
P
A
R R
A
P
B B
4/3 DCV symbol
A B
P R

31. 1. Closed Center position valve
2. Open Center position valve
3. Tandem Center position valve
• In this position all the ports are closed
to each other.
• Possibility of Heating and Damage
• In this position all the ports are open
to each other.
• No Possibility of Heating and
Damage.
• No work is done by any component.
• Used to holds the work load for some time period.
• No heating and damaging. Also supply the fluid to other circuit so, extra power
•station is required.

32. SEAT TYPE DCV (4/2 TYPE)