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Basic Pneumatics
Module 3: Directional control Valves
PREPARED BY
Academic Services
April 2012
© Applied Technology High Schools, 2012
ATM 1132 – Basic Pneumatics
2 Module 3: Directional control Valves
Module 3: Directional control valves
Module Objectives
After the completion of this module, the student will be able to:
Diffrentiate between the main types of directional control valves.
Explain the function of each type of directional control valves.
Demonstrate the function and uses of 3/2 way valve, (N/C) push button actuated.
Demonstrate the function and uses of 3/2 way valve, (N/O) push button actuated.
Demonstrate the function and uses of 3/2 way valve, (N/C) roller lever actuated.
Explain the function and uses of 5/2 way valve, selector valve.
Explain the function and uses of 5/2 way valve, single pilot valve.
Explain the function and uses of 5/2 way valve, double pilot valve.
Use the FluidSIM software to build and simulate a pneumatic circuits that contain DCV
Build a pnueumatic circuit using DCV on the Festo trainer and check its operation
Design simple pneumatic circuits for a given application.
Module Contents
Topic Page No.
1 Introduction 3
2 3/2 way valve (N/C), push button actuated 4
3 3/2 way valve (N/O), push button actuated 5
4 3/2 way valve (N/C), roller lever actuated 6
5 3/2 way selector valve 6
6 5/2 way valve 7
7 Valve actuators 9
8 Practical task 1 (Pressure dependent control) 7
9 Practical task 2 (Foil welding drum) 11
10 Supplementary resources and References 14
11 Worksheet 20
ATM 1132 – Basic Pneumatics
Module 3: Directional control valves 3
1 Introduction
Directional control valves are
devices which influence the path
taken by an air stream.
The directional control valve is
represented by two numbers.
The first number represents the
number of ports, and the second
number represents the number
of positions as shown in Fig. 3.1.
Note:
These symbols do not provide
any information about the
constructional design, but just
indicate the function of the
valve.
Fig.3.1: DCV Ports and positions
2.1 3/2 way DCV - Normally
Closed (N/C)
Way of operation:
A 3/2-way valve has 3 ports (1,
2 and 3) and 2 switching
positions (before operating and
after operating). It is
represented by the normal
position. Normally closed means
that compressed air cannot flow
through the valve as shown in
Fig. (3.2).
(a) pressure port (1) is blocked
(b) 3/2 way DCV (NC)
(before actuation)
Fig. 3.2: 3/2 way DCV (N/C) before
actuation
ATM 1132 – Basic Pneumatics
4 Module 3: Directional control Valves
When the pushbutton is actuated the
valve is opened, thus allowing the air
to flow from port (1) to port (2) as
shown in Fig. 3.3.
Un-actuated
In normally closed 3/2 way valve, a
spring-loaded disk seal blocks the air
flow from the air supply port (1) to
the working port (2). The working
port (2) is connected with exhaust
port (3) as shown in Fig. (3.2).
Actuated
Actuating this valve results in allowing
the flow from port (1) to port (2) and
blocking the exhaust port (3) as
shown in Fig. (3.3).
Fig. (3.4.a) shows the ISO symbol of
3/2 way valve normally closed (N/C)
and spring reset. Fig. 3.4.b shows the
picture of the valve.
Fig. 3.3: 3/2 way DCV (N/C) after actuation
(a) ISO symbol of 3/2 way
directional control valve N/C
(b) Picture of 3/2 way directional
control valve N/C
Fig. 3.4: 3/2 DCV (N/C) symbol
and picture
2.2 3/2-DCV - Normally Open (N/O) Way of operation:
Normally open means that compressed air
flows through the valve as shown in Fig.
(3.5.a). When the pushbutton is actuated the
valve is closed, thus stopping the air to flow
from port (1) to port (2).
(a) 3/2 way directional
control valve N/O
ATM 1132 – Basic Pneumatics
Module 3: Directional control valves 5
Un-actuated
In the normally open 3/2 way valve, a spring
loaded disk blocks exhaust port (3). The air
supply port (1) is connected to the working
port (2).
Actuated
Actuating this valve results in allowing the
flow from port (2) to port (3) and blocking
the supply air port (1).
Fig. (3.5.b) shows the ISO symbol of 3/2 way
valve normally open (N/O) and spring reset,
And Fig. 5.5.c shows the picture of the valve.
(b) ISO symbol of 3/2 way directional control valve NO
(c) Picture of 3/2 way DCV (N/O).
Fig. 3.5: 3/2 DCV (N/O)
2.3 3/2 Way- Roller Lever Valve- Normally closed (N/C)
The roller lever actuation way is
considered to be one of the most
important types of valve actuation
that is used for automatic operation of
the pneumatic cylinders. It is
generally known as pneumatic limit
switch.
2.3.1 Symbol and Construction
Fig. (3.6.a) shows the picture of the
3/2 way valve, N/C, roller lever valve.
Fig. (3.6.b) shows the ISO symbol of
the 3/2 roller lever valve.
Fig. (3.6.c) shows the construction of
the 3/2 roller lever valve.
(a) Picture of the roller lever valve
(b) ISO symbol
(c) Construction
Fig. 3.6: 3/2 way roller lever valve
ATM 1132 – Basic Pneumatics
6 Module 3: Directional control Valves
2.3.2 Function
This valve is actuated by pressing the roller lever e.g. by means of cylinder trip
cam. The valve is returned to the normal position via return spring after
releasing the roller lever.
2.4 3/2 way, selector valve
Fig. 3.7 shows the picture and the ISO
symbol of the 3/2 way, selector valve.
(a) Picture
(b) ISO symbol
Fig 3.7: 3/2 way selector valve
3. 5/2 way Directional Control Valve
This valve contains 5 ports and 2
positions. The 5/2 DCV could be
actuated manually or by using
pressure actuation (single pilot and
double pilot), or by electrical
actuation (solenoid).
3.1. Before actuated
When the 5/2-way valve is not
actuated, the flow will be from port
(1) to port (2) while the exhaust will
be from port (4) to port (5) as
illustrated in Fig. 3.8.a
(a) Initial position (before actuation)
(b) Second position (after actuation)
(c) ISO symbol of 5/2 way valve
Fig 3.8: 5/2 way valve
ATM 1132 – Basic Pneumatics
Module 3: Directional control valves 7
3.2 After actuation
After operating the valve by any method, the valve will be shifted to the
other position and in this case, the flow will be from port (1) to port (4)
while the exhaust will be from port (2) to port (3) as shown in Fig. (3.8.b).
3.3 Types of 5/2 DCV: 3.3.1 5/2 way selector valve This valve is used for manual
operation, and you can control the
valve by selector switch, and it is used
in simple applications. Fig. 3.9 shows
the picture and the ISO symbol of the
valve.
3.3.2 5/2 way single pilot valve
This valve is used for automatic
operation, and you can control the
valve by a pneumatic signal and a
spring return. Fig. 3.10 shows the
picture and the ISO symbol of the
valve.
3.3.2 5/2 way double pilot valve
This valve is used for automatic
operation, and you can control the
valve by two pneumatic signals and
this valve keeps the last position after
removing the applied signal, and it is
sometimes called memory valve. Fig.
3.11 shows the picture and the ISO
symbol of the valve.
Fig. 3.9: 5/2 way selector valve
Fig. 3.10: 5/2 way single pilot
valve
Fig. 3.11: 5/2 way double pilot
valve
ATM 1132 – Basic Pneumatics
8 Module 3: Directional control Valves
4. Valve actuators:
The pneumatic directional control
valves can be actuated (operated) in
several ways such as follows:
4.1 Manual actuators
Fig. (3.12.a) shows (from left to
right) three manual actuation
methods: manual, push button and
foot pedal.
4.2 Mechanical actuators
Fig. (3.12.b) shows (from left to
right) two mechanical actuation
methods: roller and idle return roller.
4.3 Electrical actuators
Fig. (3.12.c) shows an example of
electrical actuation (solenoid valve).
4.4 Pneumatic actuators
Fig. (3.12.d) shows an example of
pneumatic (pressure) actuation.
(a) Manual actuation
(b) Mechanical actuation
(c) Electrical actuators
(d) Pneumatic actuation
Fig. 3.12: Valve actuators
ATM 1132 – Basic Pneumatics
Module 3: Directional control valves 9
5. Pneumatic actuators
They are used to produce the required forces in
the pneumatic systems. Pneumatic actuators will
be covered in more details in modules 4 and 5
5.1 Single acting cylinder
Single acting cylinder (SAC) is an output device.
The function of the SAC is to convert the pressure
energy to mechanical energy (linear motion).
Fig. (3.13.a) shows a picture of the single acting
cylinder.
Figure (3.13.b) shows the ISO symbol of the
single acting cylinder.
5.2 Double acting cylinder
Double acting cylinder (DAC) is an output device.
The function of the DAC is to convert the pressure
energy to mechanical energy (linear motion).
Fig. (3.14.a) shows a picture of the double acting
cylinder.
Figure (3.14.b) shows the ISO symbol of the
double acting cylinder.
Note:
Single acting cylinder is used to produce linear
force in one direction only. Whereas, double
acting cylinder is used to produce linear force in
two directions.
(a) Single acting
Cylinder
(b) ISO symbol of
Single acting cylinder.
Fig. 3.13: Single acting
Cylinder
(a) Double acting cylinder
(b) ISO symbol of
double acting cylinder
Fig. 3.14: Double acting
Cylinder
ATM 1132 – Basic Pneumatics
10 Module 3: Directional control Valves
6- Practical Task 1: Gravity feed magazine
6.1 Learning objectives:
Upon the completion of this task, the student will be
• Familiar with indirect actuation of a double acting cylinder by using a double pilot valve.
• Using the 3/2 way roller valve for automatic return of the cylinder.
6.2 Task description:
Wooden planks are to be pushed along from a gravity feed magazine to a
clamping device as shown in Fig.3.15. By pressing a pushbutton valve one
plank is pushed by the slide out of the gravity feed magazine. After the
slide has reached the forward end position it returns to its start position.
Fig. 3.15: Positional sketch
ATM 1132 – Basic Pneumatics
Module 3: Directional control valves 11
6.3 Task requirements:
1. Draw pneumatic circuit diagram to control the movement of the
slide.
2. Simulate the circuit using Fluid SIM software.
3. Assemble the circuit practically and check its operation.
Draw the pneumatic circuit here
ATM 1132 – Basic Pneumatics
12 Module 3: Directional control Valves
7- Practical Task 2: Diverting device
7.1 Learning objectives:
Upon the completion of this task, the student will be
• Familiar with indirect actuation of a double acting cylinder by using a double pilot valve.
• Familiar with using different types of directional control valves.
7.2 Task description:
Using a diverting device, parts are to be moved from one conveyor track
onto the other in a linear sequence as illustrated in Fig. 3.17. By
operating a selector valve the oscillating piston rod of a cylinder pushes
the turntable via a pawl in stepped sequence. The parts are diverted and
transported onwards in the opposite direction. By returning the selector
valve back to the normal position the drive unit is switched off.
Fig. 3.17: Positional sketch
ATM 1132 – Basic Pneumatics
Module 3: Directional control valves 13
7.3 Task requirements:
1. Draw a pneumatic circuit diagram to control the operation of the
piston.
2. Simulate the circuit using FluidSIM software.
3. Assemble the circuit practically and check its operation.
Draw the pneumatic circuit here
ATM 1132 – Basic Pneumatics
14 Module 3: Directional control Valves
8. For further reading, you can use the following links:
1- www.Fest-didactic.com
2- http://www.eng2all.com/vb/t28932.html
3- http://www.logiclab.hu/lesson.php?fe=2
9. Supplementary recourses
1. Pneumatics video from Festo.
2. FluidSIM software.
10. References
1- Festo manuals and workbook TP101
2- Festo manuals and textbook TP101
ATM 1132 – Basic Pneumatics
Module 3: Directional control valves 15
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ATM 1132 – Basic Pneumatics
16 Module 3: Directional control Valves
Worksheet 1 Draw the symbol of 3/2 way (N/C), roller lever valve ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………… Draw the symbol of 5/2 way, double pilot valve …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………. Draw the symbol of 3/2 way, selector valve …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………. What is the difference between 5/2 single pilot and 5/2 double pilot? ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………… What is the function of directional control valves? …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………
What is the difference between N/O and N/C valves? …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………
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