Fundamentals of vacuum technology - Festo · PDF file2.2 Displacement pump mode of operation _____ I-7 2.3 Notes regarding pump selection ... Workbooks Fundamentals of vacuum technology,

WorkbookTP 230

CD-ROM included

Festo Didactic

567258 EN

Fundamentals of vacuum technology

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K1

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1M131

1A1

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1A2

Order No.: 567258

Edition: 10/2010

Authors: Ralph-Christoph Weber

Editor: Frank Ebel

Graphics: Ralph-Christoph Weber

Layout: 01/2011, Susanne Durz, Frank Ebel

© Festo Didactic GmbH & Co. KG, 73770 Denkendorf, Germany, 2011

Internet: www.festo-didactic.com

E-mail: [email protected]

The copying, distribution and utilization of this document as well as the communication of its contents to

others without expressed authorization is prohibited. Offenders will be held liable for the payment of

damages. All rights reserved, in particular the right to carry out patent, utility model or ornamental design

registration.

© Festo Didactic GmbH & Co. KG 567258 III

Contents

Use for intended purpose __________________________________________________________________ IV

Preface _________________________________________________________________________________ V

Introduction ____________________________________________________________________________ VII

Safety precautions and work instructions ____________________________________________________ VIII

Technology package for electro-pneumatics (TP 200) ____________________________________________X

Learning objectives for the advanced level (TP 230) _____________________________________________ XI

Allocation of learning objectives per exercise _________________________________________________ XII

Equipment set for the advanced level (TP 230) ________________________________________________ XIII

Allocation of equipment per exercise ________________________________________________________ XVI

Tools for the trainer _____________________________________________________________________ XVII

Structure of the exercises ________________________________________________________________ XVII

Component designations _________________________________________________________________ XVII

CD-ROM contents _______________________________________________________________________ XVIII

Exercises and solutions

Exercise 1: Generating vacuum _______________________________________________________________ 3

Exercise 2: Selecting suction cups for various workpieces _______________________________________ 11

Exercise 3: Maintaining vacuum when using more than one suction cup ____________________________ 21

Exercise 4: Monitoring partial vacuum _______________________________________________________ 29

Exercise 5: Reducing compressed air consumption in a vacuum system ____________________________ 37

Exercise 6: Controlled release of workpieces retained by a vacuum ________________________________ 43

Exercises and worksheets







Contents

IV © Festo Didactic GmbH & Co. KG 567258

Basic principles of vacuum technology

1 Introduction to vacuum technology __________________________________________________ I-3

1.1 Vacuum technology, basic terminology ________________________________________________ I-3

1.2 Vacuum ranges ___________________________________________________________________ I-5

2 Vacuum generation in handling technology ____________________________________________ I-7

2.1 Vacuum pumps ___________________________________________________________________ I-7

2.2 Displacement pump mode of operation _______________________________________________ I-7

2.3 Notes regarding pump selection ____________________________________________________ I-10

2.4 Ejectors ________________________________________________________________________ I-11

3 Vacuum components in handling technology _________________________________________ I-17

3.1 Valves _________________________________________________________________________ I-17

3.2 Vacuum gauges _________________________________________________________________ I-17

3.3 Vacuum reservoirs _______________________________________________________________ I-18

3.4 Suction cups ____________________________________________________________________ I-19

3.5 Bellows suction cups _____________________________________________________________ I-20

3.6 Suction cup selection _____________________________________________________________ I-21

3.7 Vacuum security valves ___________________________________________________________ I-23

© Festo Didactic GmbH & Co. KG 567258 V

Use for intended purpose

The training package for “Fundamentals of vacuum technology” may only be used:

• For its intended purpose in teaching and training applications

• When its safety functions are in flawless condition

The components included in the training package are designed in accordance with the latest technology, as

well as recognised safety rules. However, life and limb of the user and third parties may be endangered, and

the components may be impaired if they are used improperly.

The training system from Festo Didactic has been developed and manufactured exclusively for training and

vocational education in the field of automation technology. The respective training companies and/or

trainers must ensure that all trainees observe the safety precautions which are described in this workbook.

Festo Didactic hereby excludes any and all liability for damages suffered by trainees, the training company

and/or any third parties, which occur during use of the equipment set in situations which serve any purpose

other than training and/or vocational education, unless such damages have been caused by Festo Didactic

due to malicious intent or gross negligence.

VI © Festo Didactic GmbH & Co. KG 567258

© Festo Didactic GmbH & Co. KG 567258 VII

Preface

Festo Didactic’s learning system for automation technology is geared towards various educational

backgrounds and vocational requirements. The learning system is therefore broken down as follows:

• Technology oriented training packages

• Mechatronics and factory automation

• Process automation and control technology

• Robotino® – training and research with mobile robots

• Hybrid learning factories

The technology packages deal with various technologies including pneumatics, electropneumatics,

hydraulics, electrohydraulics, proportional hydraulics, programmable logic controllers, sensor technology,

electrical engineering and electric drives.

The modular design of the training system allows for applications which go above and beyond the

limitations of the individual packages. For example, PLC actuation of pneumatic, hydraulic and electric

drives is possible.

VIII © Festo Didactic GmbH & Co. KG 567258

All training packages contain the following elements:

• Hardware

• Media

• Seminars

Hardware Hardware included in the training packages consists of industrial components and systems that are

specially designed for training purposes. The components contained in the training packages are specifically

designed and selected for the projects included in the accompanying media.

Media The media provided for the individual topics consist of a mixture of teachware and software. The teachware

includes:

• Technical books and textbooks (standard works for conveying basic knowledge)

• Workbooks (practical exercises with supplementary instructions and sample solutions)

• Lexicons, manuals, technical books (which provide technical information on the topics for further

exploration)

• Transparency sets and videos (for easy-to-follow, dynamic instruction)

• Posters (for clear-cut representation of facts)

Within the software category, the following programs are available:

• Digital training programs (learning content specifically prepared for the purpose of virtual training)

• Simulation software

• Visualisation software

• Software for acquiring measurement data

• Project engineering and design engineering software

• Programming software for programmable logic controllers

The teaching and learning media are available in several languages. They’re intended for use in classroom

instruction, but are also suitable for self-study.

Seminars Comprehensive seminar offerings covering the contents of the training packages round off the system for

training and vocational education.

If you have suggestions or feedback about this manual,

please send us an e-mail at [email protected].

The authors and Festo Didactic look forward to your comments.

© Festo Didactic GmbH & Co. KG 567258 IX

Introduction

This workbook is part of the learning system for automation technology from Festo Didactic GmbH & Co. KG.

The system provides a solid basis for practice-oriented training and vocational education. Training package

TP 230 deals with the subject of “Fundamentals of vacuum technology”.

Topics including vacuum generation, system design, the selection of suction grippers and typical circuits

with suction grippers are dealt with in depth. In addition, reducing compressed air consumption in vacuum

systems is also addressed.

A permanent workstation equipped with a Festo Didactic profile plate is a prerequisite for setting up the

controllers. The profile plate has 14 parallel T-slots at 50 mm intervals. A power supply unit with short-

circuit protection is used as a direct voltage source (input: 230 V, 50 Hz, output: 24 V, max. 5 A). A portable

compressor with silencer (230 V, approx. 50 litres per minute, max. 800 kPa = 8 bar) can be used for

compressed air supply.

Working pressure should not exceed 600 kPa (6 bar). Ideal control sequence reliability can be achieved by

operating the controller at a working pressure of 500 kPa (5 bar) without oil.

In addition to equipment set TP 230, you’ll also need components from equipment set TP 201 in order to

complete the 6 exercises. The theoretical fundamentals for understanding this workbook are included in the

textbook entitled

• “Pneumatics/electropneumatics”,

as well as in the appendix to this workbook.

Technical data for the individual components are also available (vacuum generators, suction cups, vacuum

switches etc.).

X © Festo Didactic GmbH & Co. KG 567258

Safety precautions and work instructions

General Trainees should only work with the controllers under the supervision of a trainer.

Observe specifications included in the technical data for the individual components and in particular all

safety instructions!

Mechanical setup • Mount all of the components securely onto the profile plate.

• Limit switches should not be actuated frontally.

• Danger of injury during troubleshooting!

• Use a tool to actuate the limit switches, for example a screwdriver.

• Only reach into the setup when it’s at a complete standstill.

Electrical setup • Electrical connections must only be established and interrupted in the absence of voltage!

• Only use connecting cables with safety plugs for electrical connections.

• Only use low voltage (max. 24 V DC).

Pneumatic setup • Do not exceed the maximum permissible pressure of 600 kPa (6 bar).

• Do not activate compressed air until all the tubing connections have been completed and secured.

• Do not disconnect tubing while under pressure.

• Danger of injury when switching compressed air on!

Cylinders may advance and retract automatically.

• Danger of accident due to tubing slipping off!

Use shortest possible tubing connections.

Wear safety glasses.

In the event that tubing slips off:

Switch compressed air supply off immediately.

• Pneumatic circuit setup:

Connect the components with plastic tubing with an outside diameter of 4 or 6 mm. Push the tubing into

the push-in connector as far as it will go.

Switch compressed air supply off before dismantling the circuit.

• Dismantling the pneumatic circuit:

Press the blue release ring down, after which the tubing can be pulled out.

© Festo Didactic GmbH & Co. KG 567258 XI

The mounting boards for the devices are equipped with mounting variants A through D:

Variant A, snap-in system Lightweight components that are not load-bearing (e.g. directional control valves). Simply clip the device

into the slot on the profile plate. Release the components from the slots by turning the blue lever.

Variant B, bolt system Components with medium load capacity (e.g. actuators). These components are clamped onto the profile

plate using T-head bolts. The blue, knurled nut is used for clamping and loosening.

Variant C, screw system For components with high load capacity and components which are seldom removed from the profile plate

(e.g. on-off valve with filter regulator). The elements are secured with socket head screws and T-head bolts.

Variant D, plug-in system Lightweight components with lock pins which cannot be subjected to loads (e.g. indicators). These are

mounted using plug adapters.

Observe the specifications in the technical data for the individual components.

XII © Festo Didactic GmbH & Co. KG 567258

Technology package for electropneumatics (TP 200)

The TP 200 technology package consists of a multitude of individual training materials and seminars. This

package is only about the topic of electropneumatic controllers. Individual components included in the

TP 200 technology package can also be included in other packages.

Important TP 200 components • Permanent workstation with Festo Didactic profile plate

• Compressor (230 V, 0.55 kW, max. 800 kPa = 8 bar)

• Equipment sets or individual components

• Optional training materials

• Practical training models

• Complete laboratory setups

Training documentation

Textbooks Pneumatics/electropneumatics

Fundamentals of pneumatic control technology

Maintenance of pneumatic components and systems

Workbooks Fundamentals of vacuum technology, TP 230

Optional teachware Set of transparencies and overhead projector

Magnetic symbols, drawing template

Electropneumatics WBT, pneumatics WBT

Electrical engineering WBTs 1 and 2, electronics WBTs 1 and 2

Set of cutaway models with storage case

FluidSIM® pneumatic simulation software

Seminars

P111 Fundamentals of pneumatics and electropneumatics

P121 Maintenance and troubleshooting for pneumatic and electropneumatic systems

P-OP Tracking down waste – economic use of pneumatics

IW-PEP Repair and maintenance in control technology – pneumatic and electropneumatic systems

P-AL Pneumatics for vocational education

P-AZUBI Pneumatics and electropneumatics for trainees

VUU Using vacuum in handling technology

P-KOMPAKT Intensive training in pneumatics and electropneumatics

Please refer to the current seminar schedule for locations, dates and prices.

You’ll find further training materials in our catalogue and on the Internet. The learning system for

automation technology is continuously updated and expanded. Transparency sets, videos, CD-ROMs and

DVDs, as well as textbooks, are available in several languages.

© Festo Didactic GmbH & Co. KG 567258 XIII

Learning objectives for the advanced level (TP 230)

• Be able to generate a partial vacuum.

• Become familiar with the function of a venturi nozzle.

• Become familiar with the effects of system pressure on the degree of vacuum achieved and on the

evacuation time with different vacuum generators.

• Become familiar with the effects of throttle points (e.g. thin or long tubing lengths, clogged silencers) on

vacuum generation.

• Be able to control and adjust vacuum.

• Become familiar with the effects of diameter on suction cup holding force.

• Be able to select suitable suction cups for various workpieces.

• Become familiar with the effects of workpiece surface on suction cup holding force.

• Become familiar with the effects of workpiece surface on holding force.

• Become familiar with the methods for maintaining vacuum in the event that, when using several suction

cups, not all of them retain their grip.

• Be able to grip workpieces without flat surfaces using vacuum grippers.

• Be able to monitor partial vacuum with a pressure switch.

• Be able to perform this type of monitoring under various conditions.

• Be able to set up a circuit which makes it possible to minimise compressed air consumption in a vacuum

system.

• Be able to calculate the cost savings and amortisation time for compressed air economy circuits.

• Be able to release workpieces from the suction gripper in a controlled fashion after transport has been

completed using a compressed air economy circuit.

XIV © Festo Didactic GmbH & Co. KG 567258

Allocation of learning objectives per exercise

Exercise 1 2 3 4 5 6

Learning objectives

Be able to generate a partial vacuum. • Become familiar with the function of a venturi nozzle. • Become familiar with the effects of system pressure on

the degree of vacuum achieved and on the evacuation

time with different vacuum generators. •

Become familiar with the effects of throttle points (e.g.

thin or long tubing lengths, clogged silencers) on

vacuum generation. •

Be able to control and adjust vacuum. • • • Become familiar with the effects of diameter on

suction cup holding force. •

Be able to select suitable suction cups for various

workpieces. •

Become familiar with the effects of workpiece surface

on suction cup holding force. •

Become familiar with the effects of workpiece surface

on holding force. •

Become familiar with the methods for maintaining

vacuum in the event that, when using several suction

cups, not all of them retain their grip. •

Be able to grip workpieces without flat surfaces using

vacuum grippers. • •

Be able to monitor partial vacuum with a pressure

switch. •

Be able to perform this type of monitoring under

various conditions. •

Be able to set up a circuit which makes it possible to

minimise compressed air consumption in a vacuum

system. •

Be able to calculate the cost savings and amortisation

time for compressed air economy circuits. •

Be able to release workpieces from the suction gripper

in a controlled fashion after transport has been

completed using a compressed air economy circuit. •

© Festo Didactic GmbH & Co. KG 567258 XV

Equipment set for the advanced level (TP 230)

The equipment set has been put together for basic training in the field of electro-pneumatic control

technology. It includes all the elements which are necessary for achieving the specified learning objectives,

and can be supplemented with any other equipment sets. A profile plate, an electrical power supply unit,

various components from TP 201 and a source of compressed air are also required in order to set up

functional controllers.

Equipment set (TP 230)

Designation Order no. Quantity

Suction cup (black), 20 mm 573043 1

Suction cup (black), 30mm 573044 1

Suction cup (transparent), 20 mm 573045 1

Suction cup (transparent), 30mm 573046 1

Bellows suction cup, 3.5 convolutions (transparent), 20 mm 573047 2

Oval suction cup, 4 x 20 mm 573057 4

Vacuum generator 05 H 573258 1

Vacuum generator 05 L 573259 1

Air reservoir 152912 1

Non-return valve 153462 1

Flow control valve 193972 1

Vacuum gauge 573042 1

Vacuum switch 548624 1

Required components from TP 201

Designation Order no. Quantity

3/2-way solenoid valve, normally closed 539776 1

5/2-way solenoid valve as 3/2, normally open 539777 1

Signal input, electrical 162242 1

Relay, 3-way 162241 1

Distributor block 152896 1

Push-in T-connector 153128 2

On-off valve with filter-regulator 540691 1

XVI © Festo Didactic GmbH & Co. KG 567258

Equipment set symbols

Designation Symbol

Relay, 3-way

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4442

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A1

A2

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11 21 41

A1

A2 31

1412 2422 3432 4442

11 21 31 41

A1

A2

Signal input, electrical 13 21

14 22

13 21

14 22

13 21

14 22

13 21

14 22

3/2-way solenoid valve,

normally closed

2

1M131

1M1

12

© Festo Didactic GmbH & Co. KG 567258 XVII

Designation Symbol

5/2-way solenoid valve

Air reservoir

Vacuum switch

p

Non-return valve

1

2

Flow control valve

1

2

Vacuum generator

2

31

Suction cup

XVIII © Festo Didactic GmbH & Co. KG 567258

Allocation of components per exercise


Component

Suction cup (black), 20mm 1


Suction cup (transparent), 20mm 1

Suction cup (transparent), 30mm 1

Bellows suction cup, 3.5 convolutions

(transparent), 20 mm with suction valve 1 2 2 2 2

Oval suction cup, 4 x 20 mm 1

Vacuum generator 05 L 1 1 1

Vacuum generator 05 H 1 1 1 1 1 1

Air reservoir 1

Non-return valve 1 1

Flow control valve 1 (1)

Vacuum gauge 1 1 1

Vacuum switch 1 1 1

The following components from the TP 201 training package are also required.


Component


3/2-way solenoid valve, normally closed 1 1 1 1 1 1

5/2-way solenoid valve as 3/2, normally

open 1 1 1

Pressure regulator 1 1 1 1 1 1

Signal input, electrical 1 1 1 1 1 1

Relay, 3-way 1 1 1 1 1 1

Distributor block 1 1 1 1 1 1

On-off valve with filter-regulator 1 1 1 1 1 1

Power supply unit, 24 V DC 1 1 1 1 1 1

© Festo Didactic GmbH & Co. KG 567258 XIX

Tools for the trainer

Learning objectives The basic learning objectives for the exercises are the systematic drafting of circuit diagrams, as well as the

practical setup of the controller on the profile plate. This direct interaction involving both theory and

practice ensures faster progress. Concrete, individual learning objectives are assigned to each exercise.

Important learning objectives are in parentheses in the revision sections.

Equipment set elements The exercise book and the equipment set match each other. For all the exercises, you’ll only need the

elements included in the equipment set for the TP 201 basic level.

Each exercise in the basic level can be set up on a profile plate.

Structure of the exercises

All the exercises in part A have the same structure and layout and are broken down into:

• Title

• Learning objectives

• Problem description

• Parameters

• Project assignment

• Worksheets

The trainer’s manual includes the solutions for all the exercises.

Component designations

Pneumatic components are designated in circuit diagrams in accordance with ISO 1219-2. All the

components included in any given circuit have the same primary identifying number. Letters are assigned

depending on each respective type of component. Consecutive numbers are assigned if several components

of the same type are included within a single circuit. Pressure lines are designated with a P and are

numbered separately.

Drives: 1A1, 2A1, 2A2 ...

Valves: 1V1, 1V2, 1V3, 2V1, 2V2, 3V1 ...

Sensors: 1B1, 1B2 ...

Signal inputs: 1S1, 1S2 ...

Accessories: 0Z1, 0Z2, 1Z1 ...

Pressure lines: P1, P2 ...

XX © Festo Didactic GmbH & Co. KG 567258

CD-ROM contents The workbook is included on the CD-ROM as a PDF file. The CD-ROM also provides you with additional

media.

The CD-ROM contains the following folders:

• Technical data

• Demo

• Festo catalogue

Technical data The technical data for the components included in the technology package are available as PDF files.

Demo A demo version of the FluidSIM® pneumatics software package is included on the CD-ROM. Even this demo

version is suitable for testing controllers developed by the user.

Festo catalogue You’re provided with the pages from the Festo AG & Co. KG catalogue for specific components. The

representations and descriptions of the components in this format are intended to demonstrate how the

components are presented in an industrial catalogue. Additional information about the components is also

included.

© Festo Didactic GmbH & Co. KG 567258 1

Exercises and solutions







2 © Festo Didactic GmbH & Co. KG 567258


Exercise 1 Generating vacuum

Learning objectives After completing this exercise:

• You’ll be able to generate a partial vacuum.

• You’ll be familiar with the function of a venturi nozzle.

• You’ll be familiar with the effects of system pressure on the degree of vacuum achieved and on the

evacuation time with different vacuum generators.

• You’ll be familiar with the effects of throttle points on vacuum generation.

• You’ll be able to control and adjust vacuum.

Problem description A handling unit for different workpieces needs to be developed. Your job is to examine various components

and investigate the possible use of vacuum technology. First of all, you’ll have to examine components used

for vacuum generation.

Parameters • Use the vacuum generators included in the equipment set.

Project assignment 1. Describe the mode of operation of a vacuum generator.

2. Set up the test circuit.

3. Measure the vacuum generated and the evacuation time with various vacuum generators.

4. Draw characteristic curves for both vacuum generators.

5. Compare the two vacuum generators and describe their differences.

6. List any possible negative effects on vacuum generation.

Exercise 1 – Generating vacuum


Mode of operation of a vacuum generator based on the venturi principle

– Name the various components and ports of the vacuum generator shown below. Enter the

corresponding designations to the right of the numbers in the table.

Exhaust port, supply port, collector nozzle, jet nozzle, vacuum port

4

5

1

2 3

Vacuum generator

Number Designation

1 Supply port

2 Jet nozzle

3 Collector nozzle

4 Exhaust port

5 Vacuum port

– Describe the mode of operation of the vacuum generator based on the venturi principle.

Compressed air flows from the supply port (1) through a restriction, i.e. the vacuum generator’s jet

nozzle (2). Air flow velocity is increased at this restriction to ultrasonic speeds. After the air exits the

jet nozzle, it expands and flows through the collector nozzle (3) and out of the exhaust port (4). Partial

vacuum occurs in the chamber around the jet nozzle during this process. As a result, air is drawn in

through the vacuum port.



Measuring the degree of partial vacuum generated with various vacuum generators

Set up the controller in accordance with the circuit diagram shown below. Measure the degree of partial

vacuum achieved with the vacuum generator at different system pressures. Compare the two vacuum

generators included in the equipment set.

– Enter the acquired values in the table below.

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1V3

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System

pressure

Vacuum generator VN-05-H-T3-PQ2-VQ2-RQ2 Vacuum generator VN-05-L-T3-PQ2-VQ2-RQ2

Degree of partial vacuum achieved (bar) Degree of partial vacuum achieved (bar)

1 bar -0.08 0

2 bar -0.34 -0.14

3 bar -0.54 -0.2

4 bar -0.7 -0.3

5 bar -0.77 -0.38

6 bar -0.8 -0.42



Drawing the partial vacuum curve

– Enter the characteristic curves of both vacuum generators for the degree of partial vacuum achieved in

the diagram below (pu = partial vacuum, p = system pressure).

1 42 53 7

-0,1

-0,5

-0,2

-0,6

-0,3

-0,7

-0,4

-0,8

-1,0

p

VN-05-H-T3-PQ2-VQ2-RQ2

VN-05-L-T3-PQ2-VQ2-RQ2

pU

Degree of partial vacuum achieved relative to operating pressure



Measuring evacuation time for both vacuum generators

Set up the circuit described above in accordance with the circuit diagram shown below. In order to be able

to compare the performance of the two vacuum generators included in the equipment set, elapsed time is

measured from the moment operating pressure (6 bar) is switched on until a defined degree of partial

vacuum is reached.

Note:

The reservoir is required in order to ensure that the amount of time required for evacuation is actually

measurable, and thus simulates evacuation of a larger vacuum system. Use a clock or a stopwatch to

measure elapsed time.

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K1

S2

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32

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1M131

1V1

2

31

1V2

1V3

1Z1

2

31

1Z2



– Measure evacuation time for all the listed values and enter the evacuation time for both vacuum

generators in the table included below. Set system pressure to 6 bar for this exercise.

Partial

vacuum (bar)

Vacuum generator VN-05-H-T3-PQ2-VQ2-RQ2 Vacuum generator VN-05-L-T3-PQ2-VQ2-RQ2

Evacuation time (s) Evacuation time (s)

-0.1 bar 0.4 -

-0.2 bar 0.8 0.4

-0.3 bar 1.0 0.8

-0.4 bar 1.8 2.0

-0.5 bar 2.4 Max. -0,44 bar

-0.6 bar 3.5

-0.7 bar 5.8

-0.8 bar 10.0

– Enter the determined evacuation times in the graphic shown below, and draw characteristic curves for

both vacuum generators.

-0,4-0,2 pU -0,80

2

4

6

10

0

t (s)

VN-05-H-T3-PQ2-VQ2-RQ2

VN-05-L-T3-PQ2-VQ2-RQ2



Vacuum generator comparison

– Describe the differences between the two vacuum generators used and their respective advantages for

vacuum generation.

Vacuum generator VN-05-H-T3-PQ2-VQ2-RQ2:

This type of vacuum generator achieves a higher level of vacuum.

The maximum vacuum level is generated with low system pressure.

However, this vacuum generator requires significantly more evacuation time than the other.

This type of vacuum generator should be used when the suction grippers require greater holding

forces, for example in order to reliably retain heavy loads.

Vacuum generator VN-05-L-T3-PQ2-VQ2-RQ2:

This vacuum generator achieves relatively low levels of vacuum in comparison with the other

(approx. 50%).

High system pressure is required in order to reach maximum achievable vacuum.

On the other hand, it needs only minimal evacuation time in order to generate a partial vacuum.

This vacuum generator is used when a large vacuum system has to be evacuated quickly. Type L

vacuum generators are used especially where minimal vacuum and/or short cycle times are required.

Influences on vacuum generation

– Which other influences, in addition to changing system pressure and the size of the system to be

evacuated, might have negative effects on the generation of a partial vacuum by means of a vacuum

generator? Write them down.

Long or restricted tubing connections between the ejector and the suction cup.

Long or restricted compressed air supply line to the ejector.

Contaminated or clogged silencer.

Branch TEEs and angle connectors in the vacuum lines.



Influence of restrictions on vacuum generation

A flow control valve is installed in the respective line in order to simulate restrictions and other unfavourable

conditions in compressed air or vacuum lines. A restriction can then be simulated by closing the flow control

valve. Set the flow control valve to a specific degree of restriction, and leave this setting unchanged for the

entire duration of the experiment.

– Simulate the influences listed in the table with regard to degree of partial vacuum and evacuation time.

Influence Vacuum generator (type H) Vacuum generator (type L)

Contaminated silencer

Throttle point between the vacuum generator

and the silencer

Evacuation time:

Max. vacuum

Evacuation time:

Max. vacuum

Kink in the vacuum line between the suction

cup and the vacuum gauge, and between the

vacuum generator and the vacuum gauge.

If there’s a kink at either of these places,

vacuum collapses at the suction cup.

However, if the kink is located between

the vacuum gauge and the suction cup,

vacuum is still indicated.

If there’s a kink at either of these places,

vacuum collapses at the suction cup.

However, if the kink is located between

the vacuum gauge and the suction cup,

vacuum is still indicated.

Restriction in the air supply line

Throttle point between the pressure regulator

or the directional control valve and the vacuum

generator

The smaller the throttle cross-section,

the lower the degree of vacuum that can

be achieved



be achieved

Restriction in the vacuum line

Throttle point between ambient pressure and

the vacuum generator with vacuum gauge in-

between. Simulates a porous workpiece.



be achieved



be achieved

Measure evacuation time until the maximum

degree of partial vacuum is achieved (with

reservoir) with varying vacuum line lengths.

10 cm

100 cm

15 seconds

22 seconds

3 seconds

5 seconds

Documents

Fundamentals of vacuum technology - Festo · PDF file2.2 Displacement pump mode of operation _____ I-7 2.3 Notes regarding pump selection ... Workbooks Fundamentals of vacuum technology,