lab manual pneumatics

8/10/2019 Lab Manual Pneumatics

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1. BASIC PNEUMATICS

1.1 Elements of a Pneumatic Automation System

Important Components

a) FRL unit.

b) 3/2 push buttons.

c) 5/2 push button.

d) AND gate(Dual pressure valve)

e) OR Gate (Shuttle valve).

f)

5/2 way Single pilot Valve.

g) 5/2 way double pilot Valve.

h) 3/2 roller lever valve.

i) Time delay valve.

j) One way flow control valve.

k) Pressure sequence valve.

l) Single acting cylinder.

m)

Double acting cylinder.

Fig. 1 Elements of a pneumatic automation system


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1.2 Symbols of Working Elements in Pneumatic Systems


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1.3 Port Numbering and Lettering System

1, P Reserved for Pressure Source.

3, 5 S, R Reserved for exhaust ports.

2, 4 B, A Reserved for output ports.

As a general rule Odd numbers are at the bottom

and Even numbers on the top.


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1.4 Direction Control Valves: Reading from Symbols and Methods of

Actuations.


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1.5 Types of Actuation

Note: A 5/2 way valve can be converted into a 3/2 way valve as shown in figure below:

Normally closed 3/2 valve Normally open 3/2 valve


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2. Pneumatic Circuits

2.1 Construct the following circuits using different components on the Basic Pneumatic

Kit.

a) Control a single acting cylinder through a 3/2 push button and 3/2 way valve.

b) Control a double acting cylinder through a push button and 5/2 way Spring return

valve.

c) Control of a double acting cylinder through two push buttons and 5/2 way

Pneumatic valve. Use separate push buttons for the Extension and retraction of the

cylinder.

Components:

a) Single acting cylinder.

b) Double acting cylinder.

c) 3/2 Push buttons.

d) 5/2 way valve (spring return).

e) 5/2 way double pilot valve.

Observations:

a) When the 3/2 push button is pressed, the compressed air activates the 3/2 way

valve (Converted from the 5/2 way valve). This provides the passage to the

compressed air from the front end of the single acting cylinder thereby causing its

extension. Refer Fig.2.1 (a)

b) When the 3/2 push button is pressed, the compressed air activates the 5/2 way

single pilot valve. This provides the passage to the compressed air from the front end

of the double acting cylinder thereby causing its extension. On releasing the push

button, the 5/2 way valve comes to its initial position which enables the compressed


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air to enter from the backside of the double acting cylinder thereby causing its

retraction.Refer Fig. 2.2 (b)

c) When one 3/2 push button is pressed, the compressed air activates the 5/2 way

double pilot valve to move the spool forward. This provides the passage to the

compressed air to enter from the front end of the double acting cylinder thereby

causing its extension. When the other3/2push button is pressed, the compressed

air activates the 5/2 way double pilot valve to move the spool backwards and

enables the compressed air to enter from the backside of the double acting cylinder

thereby causing its retraction.Refer Fig. 2.2 (c)

Fig 2.1Circuits diagrams for Ex. 2.1

(a) (b)

(c)


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2.2 Construct the following circuits using different components on the Basic Pneumatic Kit.

a) Actuation of return stroke of a double acting cylinder by any of the two push buttons

(OR gate) and sensing with a roller sensor. Immediate forward stoke by sensing the

rear position of cylinder (Use the flow control valves).

b) Actuation of a double acting from two push buttons pressed simultaneously (AND

gate). The actuation must be possible by getting a confirmation from a sensor. The

quick retraction is possible from a separate push button only after confirmation of

full extension.

c) Continuous reciprocation of a double acting cylinder on switching a 3/2 way push

button.

Components:

a) Double acting cylinder.

b) 3/2 Push buttons

c) 5/2 way double pilot valve.

d)

3/2 roller lever valve.

e) One way flow control valves.

f) Shuttle valve (OR )

g) Dual Pressure valve (AND.)

h) Quick exhaust valve.

Observations:

a) Observe the input of compressed air supply given to the double acting cylinder in

order to perform its return stroke from the initial extended position. As two push

buttons are connected by OR gate activation by any one of them will enable the

compresses air to activate the 5/2 way valve. However as the connection is given

through the roller sensor; the activation is only possible after the roller sensor is

pressed. You can check this by operating the roller sensor by hand. As soon as the


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cylinder returns to its retracted position, the roller sensor activates the 5/2 way

valve which in turn extends the cylinder. Refer Fig 2.2 (a)

b) As the two push buttons are connected by AND gate, simultaneous activation of

both is required to activate the circuit. Also similar to (a) the confirmation from the

roller sensor is needed to activate the 5/2 way valve. This will lead to the forward

motion of the cylinder. Use a flow control valve to have a slow forward stroke. After

sensing the full extension by a roller lever valve, the fast retraction can be achieved

by a quick exhaust valve.Refer Fig 2.2 (b)

c) Here as soon as the push button is pressed and the cylinder is confirmed by a roller

lever valve at its retracted position, 5/2 way valve will activate the forward motion of

the cylinder. On extension, one more roller valve will activate the retraction of the

cylinder. This will be continued till the Push button is set off. Refer Fig 2.2 (c)

Fig.2.2 Circuits diagrams for Ex. 2.2

(a) (b)

(c)


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2.3 Construct the following circuits using different components on the Basic Pneumatic

Kit.

a) Actuation (extension) of a double acting cylinder from two push buttons pressed

simultaneously (AND gate) and when cylinder at its retracted position. The retraction

is automatic when forward end position is confirmed and preset pressure has been

reached. Immediate retraction is possible if a push button (Emergency switch) is

pressed.

b) Actuation (extension) of a double acting cylinder through a push button when

cylinder is at its retracted position. Slow building of pressure when the cylinder is at

its forward position. The retraction is possible when forward end position is

confirmed and preset pressure of 4 bar has been reached and it is held with this

pressure for 5 S. The restarting is possible 20 S after the retracted position is

reached.

c) Sequencing of two cylinders having sequence of A+B+B-A-, A+B+A-B-etc.

Components:

a) Double acting cylinder.

b)

3/2 Push buttons

c) 5/2 way double pilot valve.

d) 3/2 roller lever valve.

e) One way flow control valves.

f) AND gate.

g) Time delay valve.

h) Pressure sequence valve.

i) Pressure gauge.

Observations:

a) Here we are actually checking how much pressure the cylinder exerts after its

extension. A pressure sequence valve is used for this purpose. The extension of

cylinder is sensed by a roller lever valve, however instead of connecting it directly to

the 5/2 way valve to affect the cylinder retraction, connect it through a pressuresequence valve by presetting a particular pressure. The indicator terminal of the


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valve (Port Z) can be connected to the inlet of the cylinder through a gauge so that

we can actually monitor the pressure building in the cylinder. As the output of the

pressure sequence valve is connected to the 5/2 way valve, the retraction is possible

after the preset pressure is reached. An OR gate is used to have the retraction if an

emergency switch is pressed. Refer Fig.2.3(a)

b) The same circuit as above can be constructed with addition of Time Delay Valves.

Refer Fig.2.3(b)

c) Using the roller sensors of first cylinder as inputs to the 5/2 way valves of the second

cylinder we can achieve the cylinder sequencing as required. Refer Fig. 2.3(c)

(a) (b)


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Fig 2.3 Circuits diagrams for Ex. 2.3

(c)


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3. ELECTRO PNEUMATICS

3.1

a) To identify different electro pneumatic components and understand their

working.

b) To study the latching logic and obtain an electric circuit having a latch ( Fig. 3.1)

Components: In addition to the components that are used in basic pneumatics, study

following components:

a) 5/2 single solenoid valve.

b) 5/2 double solenoid valve.

c)

Distribution and power supply units.

d) Magnetic reed switches.

e) Capacitive proximity sensor.

f) Optical sensor.

g) Inductive proximity sensor.

h) Relays.

Fig. 3.1 Latching


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3.2: Construct the following circuits using different components on the Electro-

pneumatic Kit.

a) Extension of a double acting cylinder on pressing a push button S1and retraction of

the cylinder using a push button S2.

b) Extension of a double acting cylinder on pressing a push button S1 AND S2 OR S3.

Immediate retraction on switching off the any of the switches.

c) Slow extension of a double acting cylinder on pressing a push button S1. Quick return

of the cylinder only after confirming the full extension.

Components:

a)

5/2 single solenoid valve.

b) 5/2 double solenoid valve.

c) Distribution and power supply units.

d) Magnetic reed switches.

e) Relays.

Observations:

a)

Pressing the switch S1energizes the one end of the solenoid valve .This causes the

extension of the cylinder. Pressing the switch S2 energizes the other end of the

solenoid valve .This causes the retraction of the cylinder. Refer Fig. 3.2 (a)

b) S1and S2are connected in series thus forming the AND logic while S3 is connected in

parallel to tem thus forming the OR logic. If a single solenoid valve is used,

immediate retraction is possible on immediate switching off any of the switches.

Refer Fig. 3.2 (b)

c) Use flow control valve to achieve the slow extension of the cylinder. To confirm full

extension use magnetic reed type sensor and give its output to the return end of a

double solenoid valve. Achieve the fast retraction through a quick exhaust valve.

Refer Fig. 3.2 (c)


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Fig 3.2Circuits diagrams for Ex. 3.2

(a)

(b)

(c)


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3.3 Construct the following circuits using different components on the Electro-

pneumatic kit.

a) Extension of a double acting cylinder when a NO and NC sensors sense different

aspects of an object. Retraction on confirming the full extension using a capacitive

sensor.

b) Use a push button to start oscillation of a double acting cylinder. It must be stopped

by switching off another button. (Use of latching).

c) Obtain the sequential logic of two double acting cylinders having sequence A+B+B-A-

with latching logic incorporated in it. Also try the same using different sensors.

Components:

1) 5/2 single solenoid valve.

2) 5/2 double solenoid valve.

3) Distribution and power supply units.

4) Magnetic reed switches.

5) Relays.

6)

Double acting cylinders.

Observations:

Understand the application of latching logic when integrated with the pneumatic circuit.

Understand the principal of operations of a capacitive, inductive and optical proximity

sensor.


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(a)

b


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Fig 3.3 Circuits diagrams for Ex.3.3

(c)


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Important References:

1. Werner Deppert and kurt Stoll: Cutting Costs with Pneumatics: VogelBuchverlag Wurzburg.

2. Learning System For Automation Technology, Festo Didactic: Pneumatics

Workbook: basic Level.

3. G. Prede and D. Scholz, Electropneumatics basic level, Festo Didactic.

4, Andrew Par, Hydraulics and Pneumatics, Butterworth-Heinemann; 2

edition.

lab manual pneumatics

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