Cleaning Hidrolik.pdf 362j46

Testline Maintenance Manual

015-040-301 B

l

Copyright information Trademark information information

© 1999 MTS Systems Corporation. All rights reserved. MTS is a ed trademark of MTS Systems Corporation. MTS Systems Corporation 14000 Technology Drive Eden Prairie, Minnesota 55344-2290 USA Toll free phone: 800-328-2255 (within the USA or Canada) Phone: 612-937-4000 (outside the USA or Canada) Fax: 612-937-4515 E-mail: [email protected] http://www.mts.com ISO 9001 Certified

Publication information

MANUAL PART NUMBER

PUBLICATION DATE

011-040-301 B

November 1999

Contents Preface 5 About This Manual 6 What You Are Expected to Know 7 Conventions 8 ing MTS 11 What to Expect When You Call 12 Customer 14

Chapter 1

Installation and Modification Guidelines 15

General Guidelines 16 Hydraulic Fittings 17 Hydraulic Hoses 18 Pneumatic Fittings and Hoses Accumulators 20 System Control Cables 21

19

Chapter 2

Maintenance Logs 23

Appendix A

Fastener Requirements 35

Appendix B

Hydraulic Fluid Care 41

Recommended Hydraulic Fluids 42 Fluid Characteristics 43 Hydraulic Fluid Maintenance Schedule 45 Hydraulic Fluid Maintenance Procedures 48 Cleaning the Hydraulic Fluid 49 Replacing the Hydraulic Fluid 50 Flushing the System 51 Flushing the System with Solvent 53 Removing Water from Oil 55 Hydraulic Fluid Disposal 56 HPS Startup in Special Circumstances 57

Contents

3

Appendix C

Heat Exchanger Care 59

Types of Heat Exchangers 60 Major Components—Water-to-Oil Heat Exchanger 61 Major Components—Air-to-Oil Heat Exchanger 62 Heat Exchanger Operating Conditions 63 Water-to-Oil Exchanger Life Expectancy 65 Signs of Failure in a Water-to-Oil Heat Exchanger 66 Preventing Water-to-Oil Heat Exchanger Failures 67 Improving the Life of a Water-to-Oil Heat Exchanger 71 Water-to-Oil Heat Exchanger Maintenance Schedule 73 Water-to-Oil Heat Exchanger Troubleshooting 77 Air-to-Oil Heat Exchanger Maintenance Schedule 78 Air-to-Oil Heat Inspection and Cleaning Procedure 79

4

Contents

Preface Safety first!

Before you attempt to use your MTS product or system, read and understand all safety information. General safety information is described in the Safety manual, and product- or system-specific safety information is described in hazard notices found in your MTS manuals. Improper installation, operation, or maintenance of your system can result in hazardous conditions that can cause personal injury or death, and damage to your equipment and specimen. It is very important that you remain aware of hazards that apply to your system.

Contents

About This Manual

6

What You Are Expected to Know Conventions ing MTS

7

8 11

What to Expect When You Call Customer

12

14

Preface

5

About This Manual Purpose Summary

This manual provides a guide to basic maintenance of your system. This manual includes the following chapters. Chapter 1, “Installation and Modification Considerations”—This chapter provides guidelines to minimize operating hazards when modifications are made to the system. Chapter 2: “Maintenance Logs”—This chapter contains a maintenance log which you can use for your system. Appendix A: “Fastener Requirements”—This appendix contains information about fastener ratings and torques. Appendix B: “Hydraulic Fluid Care”—This appendix contains information that can extend the service life of hydraulic fluid. Appendix C: “Heat Exchanger Care”—This appendix contains information that can help you extend the service life of heat exchangers.

6

Preface

What You Are Expected to Know Microsoft Windows NT knowledge

Some maintenance procedures require operting the system. To operate this system, you should have a working knowledge of the Microsoft® Windows NT® before you use your system. For example, you should be able to:

Testing knowledge

•

Use the mouse.

•

Maneuver around the desktop.

•

Locate, open, close, copy, and save documents.

•

If you are not sure how to do these things, take some time to learn them before you continue.

A premise of this manual is that you have had some experience or exposure to servohydraulic testing, or access to someone who has.

Preface

7

Conventions The following paragraphs describe some of the conventions that are used in your MTS manuals.

Hazard conventions

Hazard notices are embedded in this manual and contain safety information that is specific to the task to be performed. Hazard notices immediately precede the step or procedure that may lead to an associated hazard. Read all hazard notices carefully and follow the directions that are given. Three different levels of hazard notices may appear in your manuals. Following are examples of all three levels. Note

Danger notices

DANGER

For general safety information, see the Safety manual included with your system.

Danger notices indicate the presence of a hazard which will cause severe personal injury, death, or substantial property damage if the danger is ignored. For example:

High intensity light and dangerous radiation are emitted by class 3B lasers. Viewing a class 3b laser directly or viewing it using optical instruments will cause immediate and severe injury. Avoid eye or skin exposure to the laser beam. Ensure that all power to the laser is off before attempting any maintenance, service, or adjustment procedure.

8

Preface

Warning notices

WARNING

Warning notices indicate the presence of a hazard which can cause severe personal injury, death, or substantial property damage if the warning is ignored. For example:

Hazardous fumes can accumulate in the test chamber as a result of testing. Breathing hazardous fumes can cause nausea, fainting, or death. Ensure that the chamber is properly ventilated before you open the chamber door or put your head or hands into the chamber. To do this, ensure that the temperature controller is off and that you allow sufficient time for the ventilation system to completely exchange the atmosphere within the chamber.

Caution notices

CAUTION

Caution notices indicate the presence of a hazard which will or can cause minor personal injury, cause minor equipment damage, or endanger test integrity if the caution is ignored. For example:

This specimen can develop sharp edges as a result of testing. Handling the specimen with unprotected hands can result in cuts and slivers. Always wear protective gloves when you handle the specimen.

Preface

9

Other conventions Notes

Other conventions used in your manuals are described in the following paragraphs. Notes provide additional information about operating your system or highlight easily overlooked items. For example: Note

Important notes

Using multiple instances of the scope (on multiple stations) can slow system response time.

Important notes provide information critical to operating your system, but not so critical that it involves injury or equipment. Important notes should be read. For example: Important

Control names

10

Preface

In the Level Units list, selecting the scientific notation display feature may result in the loss of original level values. If your selection moves the original level value beyond four digits, the original value will be lost.

References to items shown in windows, including window names, window controls, menu names, and menu commands are shown in bold font style. References to controls on equipment, including keyboards, control s, and consoles are also shown in bold font style.

ing MTS MTS provides a full range of services after your system is installed. If you have any questions about a system or product, MTS in one of the following ways. Note

Address

If you need technical , review the following pages for information about what to expect when you us.

MTS Systems Corporation 14000 Technology Drive Eden Prairie, Minnesota USA 55344-2290

Telephone Within the U.S. or Canada

General information: 612-937-4000 Weekdays 7:30 A.M. to 5:00 P.M., Central Time Technical or spare parts: HELPLine 800-328-2255 Weekdays 7:00 A.M. to 6:00 P.M., Central Time

Outside the U.S. or Canada Fax

your local service center.

800-925-5205 (within the U.S. or Canada) 612-937-4515 (outside the U.S. or Canada) Please include an MTS name if possible.

Internet

E-mail: [email protected] Internet home page: http://www.mts.com

Preface

11

What to Expect When You Call Before you call Know your site number and system number

MTS can help you more efficiently if you have the following information available when you call. You will be asked for your site number and system number. The site number contains your company number and identifies your equipment type (material testing, simulation, and so forth). The number is usually written on a label on your MTS equipment before the system leaves MTS. If you do not have or do not know your MTS site number, your MTS sales engineer. Example site number:

C84166-W01

When you have more than one MTS system, the system (or job) number identifies which system you are calling about. You can find your job number in the papers sent to you when you ordered your system. Example system (job) number:

Know information from prior technical assistance

Identify the problem

12

Preface

303.95

If you have called regarding this problem before, we can recall your file. You will need to tell us the: •

MTS work order number

•

Name of the person who helped you

Describe the problem you are experiencing and know the answers to the following questions. •

How long has the problem been occurring?

•

Can you reproduce the problem?

•

Were any hardware or software changes made to the system before the problem started?

•

What are the model and serial numbers of the suspect equipment?

Know relevant computer information

Know relevant software information

Be prepared to troubleshoot

While on the phone

Write down relevant information

After you call

If you are experiencing a computer problem, have the following information available. •

Manufacturer’s name and model number

•

Amount of system memory

•

Network information (type and version level)

If you are experiencing a software problem, have the following information available. •

Operating software information (type and version level)

•

MTS application software information (name and version level)

•

Names of other software that are running on your computer, such as screen savers, keyboard enhancers, print spoolers, and so forth

Prepare yourself for troubleshooting while on the phone. •

Call from a telephone close to the system so that you can try implementing suggestions made over the phone.

•

Have the original operating and application software media available.

•

If you are not familiar with all aspects of the equipment operation, have an experienced nearby to assist you.

Your call will be ed by a HELPLine agent if you are calling within the United States or Canada. In addition to asking for your site number, the agent may also ask to your name, company, company address, and the phone number where you can normally be reached. Prepare yourself in case we need to call you back. •

to ask for the work order number.

•

Record the name of the person who helped you.

•

Write down any specific instructions to be followed, such as data recording or performance monitoring.

MTS logs and tracks all calls to ensure that you receive assistance and that action is taken regarding your problem or request. If you have questions about the status of your problem or have additional information to report, please MTS again.

Preface

13

Customer We want to hear from you! MTS is continually striving to improve our products and services. Please take the time to mail, fax, or e-mail your to MTS.

The Customer Quality Request

MTS manuals include a Customer Quality Request (CQR) form located in the back of the manual. Use this form to forward complaints or suggestions for improving manuals, products, or service. This form includes check boxes that allow you to select when you expect us to respond to your input. We guarantee a timely response—your is important to us.

14

Preface

Chapter 1

Installation and Modification Guidelines Overview

Contents

To reduce system hazards, review the following guidelines before installing or modifying a test system. General Guidelines Hydraulic Fittings Hydraulic Hoses

16 17 18

Pneumatic Fittings and Hoses Accumulators

19

20

System Control Cables

21

Installation and Modification Guidelines

15

General Guidelines Qualified engineer

A qualified engineer should be responsible for any system installation or modification. This engineer must consider how changes to an existing system might affect the safety and reliability of the system.

Personnel safety

Testing equipment often operates for extended periods of time with no supervision and may attract spectators. This requires that your test laboratory setup provide adequate protection for bystanders as well as operators. Make sure that anyone allowed into the test area knows the dangers involved. Make it immediately obvious to anyone how to stop the system in an emergency.

Disconnect and e-stop switches

The National Electrical Code (United States) requires that a disconnect switch be provided within view of each motor controller. Be sure that you can easily find the system power disconnect switch or emergency stop switch. Eliminate any unusual combination of switches that may cause someone unfamiliar with the system to assume that power is off when it is actually on. Properly ground all system components. Do not depend on hydraulic lines and hoses to provide electrical grounding.

16

Installation and Modification Guidelines

Hydraulic Fittings Ratings

Use only appropriately rated hydraulic fittings from a reputable manufacturer that meet National Fluid Power Association standards (NFPA, 3333 North Mayfair Road, Milwaukee, Wisconsin 53222 USA). Use pressure line fittings rated for a severe shock environment. Drain and return line fittings can be rated for low pressure if downstream valves are not installed. If valves or self-sealing hose quick connects are installed downstream and no relief valves are used, design the return line to safely withstand the highest possible system pressure.

Failure

High pressure fittings generally fail by cracking. This may not create an instantly hazardous condition. When low pressure fittings are exposed to high pressures, they fail catastrophically and create instantly hazardous conditions. Do not use fittings and tubes made out of brass or copper for high pressure fittings under any circumstances. (You can buy these fittings in hardware stores.) They are not strong enough for typical hydraulic system pressures and may rupture explosively when pressurized.

Selection

Manufacturers frequently derate pressure capabilities in fitting sizes above 12.7 mm (0.5 in.) diameter. This makes fitting selection more critical in larger sized hoses. MTS recommends 37° JIC fittings with rolled flares. Avoid the use of flareless fittings in pressure lines larger than 25.4 mm (1 in.) in diameter. These fittings are more sensitive to fatigue loading. If lines with diameters larger than 31.75 mm (1.25 in.) are needed, use split flange fittings that meet SAE standard J518c. These fittings provide better reliability and assemble with standard tools. Swivel fittings where the “B” nut (the swivel nut) is retained on the fitting using a snap ring or injected steel ring are generally less reliable than more conventional types of fittings.

Design

Design enough fittings into a system to accommodate dimensional errors without placing severe strains on the fittings or tube ends. Avoid short or straight runs of interconnected tubing. The locked-in stress from the assembly can cause the fitting to fatigue prematurely or tear the mating thread out of an adjacent manifold.

Tightening

Never tighten a fitting when it is under pressure. This is the most likely time for it to fail. Less torque is required to obtain a leakproof seal if you remove pressure before tightening the fitting.

Installation and Modification Guidelines

17

Hydraulic Hoses Ratings

Pressure and return line hoses for normal hydraulic service should have a burst pressure rating at least four times greater than your system’s operating pressure. For example, 20 MPa (3000 psi) operation requires an 80 MPa (12,000 psi) burst pressure rating.

Routings

Avoid routing that puts severe twists into hoses. Hoses become stiff in their twisted axes.

Failure

The strength of a hose assembly deteriorates with age and fatigue. In a tensile failure, the hose pulls out of its end fitting. This can produce a dangerous whipping hose if the system is operating. Consider the consequences of a tensile hose failure. Short hoses or large hoses fed only from a small pump present little hazard from whipping. The combination of a large pump and a small or medium sized pressure hose presents a greater whipping hazard. If necessary, anchor hydraulic pressure hoses to the ground or tie them to a return line within 60 cm (2 ft) of the flow outlet end. Hoses can also be run in trenches or other protected areas. Ply separation can also cause a hose to fail. Ply failure will first generally produce a blister on the hose with a small leak.. This is the start of a much larger failure. Replace any hose that has blisters or shows weakening of wire wrapping or reinforcement.

18

Installation and Modification Guidelines

Pneumatic Fittings and Hoses Ratings

Fittings and hoses used in pneumatic circuits must be rated for operating pressures in accordance with the National Fluid Power Association standards (NFPA, 3333 North Mayfair Road, Milwaukee, Wisconsin 53222 USA).

Failure

Use the same guidelines for replacing pneumatic hoses as you use for replacing hydraulic hoses.

Restraint

Install fittings and hoses so that they do not strain components. Anchor them to prevent thrashing in case of failure. Securely tie down large diameter flexible hoses since they are particularly dangerous when thrashing about. Restrain any hose over approximately 90 cm (3 ft) that carries high pressure gas near its end fittings to prevent whipping.

Installation and Modification Guidelines

19

Accumulators

20

Restraint

The accumulator screws into the manifold at a neck fitting. An accumulator can generate considerable jet thrust if its neck fitting fails. You can house small accumulators in sheet metal enclosures to protect against this type of failure. You can clamp down large accumulators to protect against this type of failure.

Mounting

Always solidly mount any accumulator manifolds which may subject the neck fittings to fatigue. Never use thin wall tubing or other highly stressed fittings to an accumulator body. Do not to expose the neck fittings to excessive vibration or mechanical resonance where accumulators attach directly to the actuator.

Installation and Modification Guidelines

System Control Cables Routing

Damaged cables are a common cause of control loop failure. Control loop failure can cause an actuator to move violently to the end of its stroke. Route cables carefully so they can not be tripped over, accidentally cut, or subject to high wear. As needed, tie down cables to reduce loads on their connectors.

Installation and Modification Guidelines

21

22

Installation and Modification Guidelines

Chapter 2

Maintenance Logs Use the following maintenance logs to record maintenance performed on your system. To use the logs: 1. Identify maintenance items. A.

Review your Product Information manuals to identify maintenance procedures and intervals. Maintenance intervals are typically given in operating hours and calendar time.

B.

Record the recommended maintenance procedures in the Procedure column.

C.

Record the recommended operating hours in the Recommended Hours column.

D. Record the recommended calendar time in the Recommended Date column. 2. Perform the maintenance procedures. 3. Record when you performed the maintenance procedure. –

When appropriate, enter the operating hours in the Actual Hours column.

–

When appropriate, enter the calendar time in the Actual Date column.

Maintenance Log

23

24

Maintenance Log

System Maintenance Log

SYSTEM _____________________________________ PAGE ______ RECOMMENDED PROCEDURE

HOURS

DATE

OF

______

ACTUAL MAINTENANCE INTERVAL AND DATE HOURS

DATE

HOURS

DATE

HOURS

DATE

HOURS

DATE

HOURS

DATE

System Maintenance Log

SYSTEM _____________________________________ PAGE ______ RECOMMENDED PROCEDURE

HOURS

DATE

OF

______

ACTUAL MAINTENANCE INTERVAL AND DATE HOURS

DATE

HOURS

DATE

HOURS

DATE

HOURS

DATE

HOURS

DATE

System Maintenance Log

SYSTEM _____________________________________ PAGE ______ RECOMMENDED PROCEDURE

HOURS

DATE

OF

______

ACTUAL MAINTENANCE INTERVAL AND DATE HOURS

DATE

HOURS

DATE

HOURS

DATE

HOURS

DATE

HOURS

DATE

System Maintenance Log

SYSTEM _____________________________________ PAGE ______ RECOMMENDED PROCEDURE

HOURS

DATE

OF

______

ACTUAL MAINTENANCE INTERVAL AND DATE HOURS

DATE

HOURS

DATE

HOURS

DATE

HOURS

DATE

HOURS

DATE

System Maintenance Log

SYSTEM _____________________________________ PAGE ______ RECOMMENDED PROCEDURE

HOURS

DATE

OF

______

ACTUAL MAINTENANCE INTERVAL AND DATE HOURS

DATE

HOURS

DATE

HOURS

DATE

HOURS

DATE

HOURS

DATE

System Maintenance Log

SYSTEM _____________________________________ PAGE ______ RECOMMENDED PROCEDURE

HOURS

DATE

OF

______

ACTUAL MAINTENANCE INTERVAL AND DATE HOURS

DATE

HOURS

DATE

HOURS

DATE

HOURS

DATE

HOURS

DATE

System Maintenance Log

SYSTEM _____________________________________ PAGE ______ RECOMMENDED PROCEDURE

HOURS

DATE

OF

______

ACTUAL MAINTENANCE INTERVAL AND DATE HOURS

DATE

HOURS

DATE

HOURS

DATE

HOURS

DATE

HOURS

DATE

System Maintenance Log

SYSTEM _____________________________________ PAGE ______ RECOMMENDED PROCEDURE

HOURS

DATE

OF

______

ACTUAL MAINTENANCE INTERVAL AND DATE HOURS

DATE

HOURS

DATE

HOURS

DATE

HOURS

DATE

HOURS

DATE

System Maintenance Log

SYSTEM _____________________________________ PAGE ______ RECOMMENDED PROCEDURE

HOURS

DATE

OF

______

ACTUAL MAINTENANCE INTERVAL AND DATE HOURS

DATE

HOURS

DATE

HOURS

DATE

HOURS

DATE

HOURS

DATE

System Maintenance Log

SYSTEM _____________________________________ PAGE ______ RECOMMENDED PROCEDURE

HOURS

DATE

OF

______

ACTUAL MAINTENANCE INTERVAL AND DATE HOURS

DATE

HOURS

DATE

HOURS

DATE

HOURS

DATE

HOURS

DATE

Appendix A

Fastener Requirements Torque requirements

Most fasteners used in MTS manufactured systems are torqued to specific design requirements to ensure a reliable product. Any time that a fastener is loosened or the configuration of a component within the system is modified, refer to the system assembly drawings (located in the “Assembly Drawings” section of your system’s Reference manual) or the tables in this appendix to determine the correct torque requirement. Over- or under-torquing a fastener may present a hazardous situation due to the high forces and pressures present in most systems. Slight over-torquing, while not recommended, may be done in certain circumstances if a fastener is not reused and the amount of over-torquing is not excessive. However, excessive over-torquing will cause the fastener to yield and may damage the mating material’s threads. The acceptable level of over-torquing depends on factors such as material types, fastener size, the number of times the fastener has been reused, and fatigue load experienced. Therefore, a rule specifying the over-torque limit for any fastener is not practically definable. If over-torquing is necessary, expect failures and take appropriate safety precautions. Under-torquing can also cause premature fastener failures. If a t connected with threaded fasteners is subjected to cyclic loading, the fasteners must be torqued (preloaded) to a combined force level higher than the cyclic load applied through the t. If this preload is less than the cyclic load, the t will separate on each cycle, causing fatigue loads on the fasteners. For example, grade 8 cap screws are usually stressed to 620 MPa (90,000 psi) when fully torqued. At that stress level, even a small cyclic strain will cause fatigue failure. If a t is inadequately preloaded due to fastener under-torquing, the cyclic strain will be substantial and the fasteners will prematurely fail.

Other considerations

Some fastener connection configurations inherently cause prying or flexing loads on the fasteners. Even though the fasteners are torqued properly, fatigue failures can still be expected to occur unless the operating stress is very low. Long tie-rods might be subjected to fatigue loading or to impact loads in some installations. In such systems, friction collars or sheet metal covers are installed to restrain a failing tie-rod from violent movement. These restraining devices should not be removed. If removal is necessary for a maintenance procedure, the restraining devices should be reinstalled and tightened before the tie-rods are tightened.

Torque tables

The following tables identify standard fastener rating and torque requirements. They should be used if no rating or torque specifications are available on the component assembly drawings in the system Reference manual. When in doubt about fastener torquing requirements, consult MTS.

Fastener Requirements

35

Ratings and Torque Requirements—U.S. Customary Sizes Coarse Thread Series (Preferred) SOCKET HEAD CAP SCREWS* TENSILE AREA

TORQUE‡ (LUBE)

WORKING FORCE

TORQUE‡ /8%(

SIZE

IN†

KN

KIP

N·M

KIP

KN

KIP

N·M

LB·FT

2 - 56

0.0037

1.04

0.233

0.51

0.38

0.74

0.166

0.36

0.27

4 - 40

0.00603

1.69

0.38

1.1

0.8

1.21

0.271

0.77

0.57

6 - 32

0.00909

2.55

0.572

2.0

1.5

1.82

0.409

1.4

1.1

8 - 32

0.014

3.93

0.883

3.7

2.7

2.8

0.63

2.6

1.9

10 - 24

0.0175

4.91

1.1

5.3

3.9

3.51

0.789

3.8

2.8

1/4 - 20

0.0318

8.92

2.0

13

9.4

6.37

1.43

9.1

6.7

5/16 - 18

0.0524

14.7

3.30

26

19

10.5

2.36

19

13.8

3/8 - 16

0.0775

21.7

4.88

47

34

15.5

3.49

33

25

7/16 - 14

0.1063

29.8

6.70

75

55

21.2

4.78

53

39

1/2 - 13

0.142

39.8

8.94

110

84

28.4

6.39

81

60

9/16 - 12

0.182

48.6

10.92

156

115

36.4

8.19

117

86

5/8 - 11

0.226

60.3

13.6

220

160

45.2

10.2

160

120

3/4 - 10

0.334

89.3

20.1

380

280

66.9

15.1

290

210

7/8 - 9

0.462

123.2

27.7

615

454

92.4

20.7

462

340

1-8

0.606

162

36.3

920

680

121

27.3

690

510

1-1/4 - 7

0.969

259

58.1

1800

1400

194

43.6

1400

1000

1-1/2 - 6

1.41

375

84.3

3200

2400

281

63.2

2400

1800

1-3/4 - 5

1.89

502

113

5000

3700

376

84.8

3800

2800

2 - 4-1/2

2.5

667

150

7600

5600

500

112

5700

4200

3-4

5.97

1590

358

27000

20000

1190

269

20000

15000

4-4

11.1

2960

665

68000

50000

2220

499

51000

37000

*

†

‡

36

WORKING FORCE

HEX BOLTS†

Use ASTM 574 or threaded rod of equal strength. For socket head cap screws with diameters less than 0.50 inches, SULT = 180 ksi, working stress = 63 ksi. For socket head cap screws with diameters greater than 0.62 inches, SULT = 170 ksi, working stress = 60 ksi. Use SAE grade 5 and ASTM A325, up to 0.75 inch diameter or threaded rod of equal strength. For threaded fasteners with SULT = 120 to 130 minimum, working stress = 45 ksi (includes SAE grade 5 screws up to 0.75 in). Torque for clamp equal to 1.5 x working force.

Fastener Requirements

Ratings and Torque Requirements—U.S. Customary Sizes Fine Thread Series SOCKET HEAD CAP SCREWS* TENSILE AREA

WORKING FORCE

TORQUE‡ (LUBE)

HEX BOLTS† WORKING FORCE

TORQUE‡ /8%(

SIZE

IN†

KN

KIP

N·M

KIP

KN

KIP

N·M

LB·FT

2 - 64

0.00393

1.1

0.248

0.54

0.4

0.788

0.177

0.39

0.29

4 - 48

0.0066

1.85

0.416

1.2

0.87

1.32

0.297

0.85

0.62

6 - 40

0.0101

2.84

0.639

2.2

1.7

2.03

0.456

1.6

1.2

8 - 36

0.0147

4.13

0.928

3.9

2.9

2.95

0.663

2.8

2

10 - 32

0.02

5.6

1.26

6.1

4.5

4

0.9

4.3

3.2

1/4 - 28

0.0364

10.2

2.29

15

11

7.28

1.64

10

7.7

5/16 - 24

0.0581

16.2

3.66

30

22

12.2

2.74

22

16

3/8 - 24

0.0878

24.6

5.53

53

39

17.6

3.95

38

28

7/16 - 20

0.119

33.3

7.48

83

61

23.8

5.34

59

44

1/2 - 20

0.16

44.8

10.1

130

94

32

7.2

91

67

9/16 - 18

0.203

54.2

12.18

174

128

40.6

9.13

131

96

5/8 - 18

0.256

68.3

15.4

240

180

51.2

11.5

180

130

3/4 - 16

0.373

99.5

22.4

430

310

74.7

16.8

320

240

7/8 - 14

0.509

136

30.6

680

500

102

22.9

510

376

1 - 14

0.68

181

40.8

1000

760

136

30.6

780

570

1-1/4 - 12

1.07

286

64.4

2000

1500

215

48.3

1500

1100

1-1/2 - 12

1.58

422

94.9

3600

2700

316

71.1

2700

2000

1-3/4 - 12

2.19

584

131

5800

4300

438

98.4

4400

3200

2 - 12

2.89

772

174

8800

6500

579

130

6600

4900

3 - 12

6.69

1790

401

31000

23000

1340

301

23000

17000

*

†

‡

Use ASTM 574 or threaded rod of equal strength. For socket head cap screws with diameters less than 0.50 inches, SULT = 180 ksi, working stress = 63 ksi. For socket head cap screws with diameters greater than 0.62 inches, SULT = 170 ksi, working stress = 60 ksi. Use SAE grade 5 and ASTM A325, up to 0.75 inch diameter or threaded rod of equal strength. For threaded fasteners with SULT = 120 to 130 minimum, working stress = 45 ksi (includes SAE grade 5 screws up to 0.75 in). Torque for clamp equal to 1.5 x working force.

Fastener Requirements

37

Ratings and Torque Requirements—SI Metric Sizes Coarse Thread Series (Preferred) SOCKET HEAD CAP SCREWS* TENSILE AREA

WORKING FORCE

TORQUE‡ (LUBE)

HEX BOLTS† WORKING FORCE

TORQUE‡ /8%(

SIZE

IN†

KN

KIP

N·M

KIP

KN

KIP

N·M

LB·FT

M3-.5

0.00769

2.05

0.461

1.4

1.0

1.54

0.346

1.0

0.77

M4-.7

0.0134

3.58

0.804

3.2

2.4

2.68

0.603

2.4

1.8

M5-.8

0.0217

5.79

1.3

6.5

4.8

4.34

0.976

4.9

3.6

M6-1

0.0307

8.21

1.84

11

8.2

6.15

1.38

8.3

6.1

M8-1.25

0.056

14.9

3.36

27

20

11.2

2.52

20

15

M10-1.5

0.0888

23.7

5.33

53

39

17.8

3.99

40

29

M12-1.75

0.129

34.4

7.74

93

69

25.8

5.81

70

51

M16-2

0.24

64.2

14.4

230

170

48.1

10.8

170

130

M20-2.5

0.376

100

22.5

450

330

75.2

16.9

340

250

M24-3

0.541

144

32.4

780

570

108

24.3

580

430

M30-3.5

0.861

230

51.6

1600

1100

172

38.7

1200

860

M36-4

1.25

335

75.3

2700

2000

251

56.5

2000

1500

M42-4.5

1.72

460

103

4300

3200

345

77.5

3300

2400

M48-5

2.26

604

136

6500

4800

453

102

4900

3600

M56-5.5

3.12

833

187

10000

7700

625

140

7900

5800

M64-6

4.12

1100

247

16000

12000

824

185

12000

8800

* † ‡

38

Use Grade 12.9 or threaded rod of equal strength with SULT = 1220 MPa, working stress = 410 MPa. Use Grade 8.8 or threaded rod with SULT = 860 MPa, working stress = 310 MPa. Torque for clamp equal to 1.5 x working force.

Fastener Requirements

Ratings and Torque Requirements—SI Metric Sizes Fine Thread Series SOCKET HEAD CAP SCREWS* TENSILE AREA

WORKING FORCE

TORQUE‡ (LUBE)

HEX BOLTS† WORKING FORCE

TORQUE‡ /8%(

SIZE

IN†

KN

KIP

N·M

KIP

KN

KIP

N·M

LB·FT

M8-1

0.0601

16

3.61

29

21

12

2.7

22

16

M10-1.25

0.0939

25.1

5.63

56

42

18.8

4.23

42

31

M12-1.25

0.142

37.8

8.49

100

75

28.3

6.37

76

56

M12-1.5

0.135

36.1

8.11

97

72

27.1

6.08

73

54

M16-1.5

0.257

68.7

15.4

250

180

51.5

11.6

190

140

M20-1.5

0.418

112

25.1

500

370

83.7

18.8

380

280

M20-2

0.397

106

23.8

480

350

79.4

17.9

360

260

M24-2

0.592

158

35.5

850

630

118

26.6

640

470

M27-2

0.764

204

45.8

1200

910

153

34.4

930

690

M30-2

0.958

256

57.5

1700

1300

192

43.1

1300

950

M36-3

1.33

355

79.9

2900

2100

267

59.9

2200

1600

M42-3

1.86

496

112

4700

3500

372

83.7

3500

2600

M48-3

2.47

660

148

7100

5300

495

111

5300

3900

M56-4

3.3

882

198

11000

8200

662

149

8300

6100

M64-4

4.4

1170

264

17000

12000

880

198

13000

9300

* † ‡

Use Grade 12.9 or threaded rod of equal strength with SULT = 1220 MPa, working stress = 410 MPa. Use Grade 8.8 or threaded rod with SULT = 860 MPa, working stress = 310 MPa. Torque for clamp equal to 1.5 x working force.

Fastener Requirements

39

40

Fastener Requirements

Appendix B

Hydraulic Fluid Care Overview

This appendix provides guidelines on the care of the hydraulic fluid used in your system. Your system’s performance depends on maintaining clean hydraulic fluid. Fluid contamination and breakdown occur normally during system operation. Failure to maintain clean hydraulic fluid will lead to poor system performance and expensive repairs.

Contents

Recommended Hydraulic Fluids Fluid Characteristics

42

43

Hydraulic Fluid Maintenance Schedule

45

Hydraulic Fluid Maintenance Procedures Cleaning the Hydraulic Fluid Replacing the Hydraulic Fluid Flushing the System

48

49 50

51

Flushing the System with Solvent Removing Water from Oil Hydraulic Fluid Disposal

53

55 56

HPS Startup in Special Circumstances

57

Hydraulic Fluid Care

41

Recommended Hydraulic Fluids MTS servohydraulic systems require a hydraulic fluid that can operate at 20 MPa (3000 psi) for hundreds of hours while experiencing high shear forces from the servovalve. The fluid must have excellent lubricating, wear, antifoam, and water-resistance characteristics. MTS recommends Mobil DTE 25. Where Mobil DTE 25 is not available, MTS recommends Shell Tellus 46. Do not mix these fluids. The petroleum industry does not have a standard for the contents of hydraulic fluid base stock or additives. The composition of hydraulic fluids can vary. MTS has used Mobil DTE 25 for years and has verified it to be consistent in composition. Once you have selected a brand and type of fluid, stick with it. Do not mix different brands or types of fluids. Mixing can produce contaminants that could damage your system.

DTE 25 specifications

The table below defines normal, borderline, and unsatisfactory characteristics for Mobil DTE 25 sampled from an HPS reservoir. Fluid that on analysis shows unsatisfactory characteristics should be changed. Borderline fluid can sometimes be improved by performing the “Cleaning the Hydraulic Fluid” procedure described later in this appendix. Mobil DTE 25 Specifications

CHARACTERISTIC

NORMAL

BORDERLINE

UNSATISFACTORY

Viscosity at 38°C (100°F)

215/240 SuS

Low 183/193; high 265/276

Low <183; high >276

Particle Count

ISO 13/9

ISO 15/11*

ISO 16/13*

Water, % by weight

<0.05

0.05-0.1

>0.1

Iron, ppm

<30

30-50

>50

Silicon, ppm

<15

15-30

>30

Copper, ppm

<15

15-30

>30

* Typical ranges—actual ranges depend on the type of test performed.

42

Hydraulic Fluid Care

Fluid Characteristics The following paragraphs describe fluid characteristics that should be analyzed. Some characteristics can be determined by look and smell; others require laboratory work.

Appearance Water content

Oxidation

Hydraulic fluid has an amber color. A milky, dark, or otherwise abnormal color may indicate contamination or chemical breakdown. Water gives hydraulic fluid a cloudy, milky appearance. It is highly undesirable in hydraulic systems. Its presence may result in the formation of emulsions and contribute to the corrosion of metal surfaces. More than a trace of water may indicate a faulty mechanical condition, such as a heat exchanger leak or water being drawn in through a reservoir breather filter during heating and cooling cycles. If water contamination exists, correct the cause and replace the hydraulic fluid. Oxidation produces a change in the fluid color and odor. It raises fluid acidity and produces sludge and varnish which can cause sticky servovalves. Oxidation naturally occurs over time and is irreversible. Fluid operating temperatures above 60°C (140°F) will increase the oxidation rate. Have the fluid analyzed more often when the system is operated at higher temperatures. Chemical analysis can determine the level of oxidation. Replace fluid that has exceeded allowable levels.

Chemical breakdown

A marked change in the smell of the hydraulic fluid can indicate a chemical breakdown. Fluid operating temperatures above 60°C (140°F) will increase the chemical breakdown rate. Contamination can also cause chemical breakdown. For example, some compounds used for sealing water pipes are not compatible with hydraulic fluid and can cause breakdown. If a chemical breakdown occurs, correct the cause and replace the fluid.

Viscosity

Viscosity is a measure of the resistance of the fluid to flow. A low viscosity fluid will not provide adequate lubrication, resulting in increased wear. If viscosity is outside the specified flow limits, replace the fluid.

Iron, silicon, and copper content

Chemical analyses for the presence of iron, silicon or copper are particularly valuable as troubleshooting aids. High iron readings may indicate pump part wear. High silicon readings may be due to dirt or may be caused by sealing or antifoaming agents that use silicon compounds. High copper readings may indicate pump wear, faulty lines and fittings, or a faulty heat exchanger. If there is excessive iron, silicon, or copper content, the clean or replace the fluid.

Hydraulic Fluid Care

43

Hydraulic fluid analysis

Analysis results are better than time as basis for determining fluid change intervals since the type of testing done determines the rate at which contaminants build up and fluid breaks down. Take fluid samples with the system at normal operating temperatures. Keep sampling tools and containers clean. Dirt introduced during sampling will produce an inaccurate analysis. MTS recommends keeping a maintenance log to record the sampling schedule, analysis results, and corrective actions. Use this log to detect signs of deterioration and to develop a fluid change schedule. The type of contaminants found can also determine what type of corrective action to take. MTS has maintenance packages that include fluid analysis available at minimal cost.

44

Hydraulic Fluid Care

Hydraulic Fluid Maintenance Schedule Use the following as a guide in maintaining your hydraulic fluid. Your operating environment may require more frequent maintenance. Prompt action on warning signals is the best preventive measure.

During installation

Before operation

8 hours/daily

During installation, protect the system from contamination when a plug, cap, hose, or other hydraulic component is removed. Dirt can enter the system through these openings and can eventually cause system failure. Before you first operate your system: •

If you have a large system that uses stainless steel tubing, first flush the system and then clean the hydraulic fluid. To flush the system, follow the instructions in the Flushing the System section of this Appendix. To clean the fluid, follow the instructions in the “Cleaning the Hydraulic Fluid” section of this Appendix.

•

If you have a large system with a complex, welded carbon steel pipe fluid distribution system, first flush the system. Have the fluid analyzed for an ISO particle count of 13/9 or better. As needed, clean the fluid to achieve a 13/9 or better particle count. To flush the system and clean the fluid, follow the instructions in the Flushing the System and Cleaning the Hydraulic Fluid sections of this Appendix.

•

Take a fluid sample after installation. Keep this first test sample to compare it to subsequent samples.

•

Prepare a maintenance log to record the sampling schedule, analysis results, and corrective actions.

Every day or after every eight hours of operation, do the following: 1. Check the fluid level in the HPS reservoir sight glass: –

A low level can indicate a leak.

–

A high level can indicate water contamination from a heat exchanger.

2. Check the hydraulic fluid for signs of excessive water contamination: –

When the system is running, look at the HPS reservoir sight glass. Water gives the fluid a cloudy, milky appearance.

–

When the system is not running, draw off a fluid sample from the bottom of the reservoir. Water will appear in your sample.

More than traces of water may indicate a faulty mechanical condition, such as a leak in the heat exchanger or water being drawn in through the reservoir breather filter during heating and cooling cycles. 3. Check the hydraulic fluid color and odor: –

Clean hydraulic fluid has an amber color.

–

A burnt caramel smell can indicate chemical breakdown.

Hydraulic Fluid Care

45

–

A milky, dark, abnormal color may indicate contamination or chemical breakdown.

4. Check all filter and fluid change indicators. 5. Note any system performance changes. Poor performance may indicate contaminated fluid and dirty filters. 6. If you detect water contamination: A.

Identify and stop the water leak.

B.

Change the filters and replace the hydraulic fluid.

7. If you detect a change in fluid smell: A.

Have the fluid chemically analyzed. Take any required corrective actions.

B.

Consult with MTS to see if any adjustments to your hydraulic system are required.

8. If your dirty filter indicators trip: A.

Identify and correct any sources of contamination.

B.

Change or clean the filter elements.

C.

Run the system for two to four hours to remove contaminants. (Run larger systems longer.)

D. Have the fluid analyzed. Clean or change it if it does not meet an ISO cleanliness level of 13/9 or better.

40 hours/monthly

Each month or after every 160 hours of operation do the following: 1. Perform a spat test to check for water contamination: A.

Put a drop of fluid on a hot plate.

B.

Spattering indicates water contamination. Analyze the fluid and take any required corrective action.

2. Get the fluid’s pH level checked for evidence of fluid contamination and breakdown following ASTM procedures D974 or D 664. 3. Check the fluid for color changes and abnormal odors. 4. Check all filter and fluid change indicators. As needed, clean or replace all dirty filter elements. 5. Check that:

46

Hydraulic Fluid Care

–

Maximum oil temperature is less than 60°C (140°F).

–

The pressure line has a 21 MPa (3000 psi) maximum static reading and a 17 MPa (2500 psi) minimum dynamic reading.

–

The maximum drain line back pressure is limited to 0.17 MPa (25 psi).

500 hours/3 months

1000 hours/6 months

Every three months or after every 500 hours of operation, take a fluid sample and have it analyzed. Record the results. Clean or replace the fluid if necessary. Every 6 months or after 1000 hours of operation, do the following: 1. Disassemble and inspect the heat exchanger core for corrosion. Clean the unit if it is dirty. Replace the unit if it is highly corroded. 2. Remove a solenoid valve and inspect the spool for varnish every 1000 operating hours. MTS if the spool is varnished.

Hydraulic Fluid Care

47

Hydraulic Fluid Maintenance Procedures This section covers the following hydraulic maintenance procedures: •

Cleaning the Hydraulic Fluid—perform this procedure when analysis shows that the fluid fails to meet an ISO cleanliness level of 13/9 or better.

•

Replacing the Hydraulic Fluid—perform this procedure if analysis shows that cleaning the hydraulic fluid fails to produce an ISO cleanliness level of 13/9 or better.

•

Flushing the System—perform this procedure whenever you change a hydraulic component such as a hose, hard-line, or HSM. Also perform this procedure whenever you change your system’s configuration.

•

Flushing the System with Solvent—perform this procedure when you need to remove sludge from the reservoir and varnish from the system.

•

Removing Water from Oil—perform this procedure after a water-to-oil heat exchanger failure has contaminated the hydraulic fluid with water.

Note

CAUTION

When adding fluid always use a transfer pump such as the MTS Model 590.01 that can provide 10 micron or better filtration. Most commercial hydraulic fluids, even when brand-new, exceed the maximum amount of contamination allowed in MTS hydraulic systems.

Mixing fluid brands can degrade system performance. Degraded performance can produce bad test results. Choose one brand and stay with it.

48

Hydraulic Fluid Care

Cleaning the Hydraulic Fluid 1. Identify and correct any sources of contamination. 2. Change or clean the filter elements as needed. 3. Run the system for two to four hours to remove contaminants. (Run larger systems longer.) 4. Get the fluid analyzed. Replace the fluid if it does not meet an ISO cleanliness level of 13/9 or better.

Hydraulic Fluid Care

49

Replacing the Hydraulic Fluid 1. Identify and correct any sources of contamination. 2. Run the HPS until fluid reaches operating temperature. 3. Turn off the HPS. 4. While the fluid is still hot, drain the HPS reservoir. As needed, wipe out the inside of the reservoir with clean cloths to remove any remaining contaminants. 5. Replace or clean the HPS filter elements. 6. Fill the reservoir with clean hydraulic fluid. Use a transfer pump that can provide 10 micron or better filtration. 7. Operate the HPS at high pressure for two to four hours. (Run larger systems longer.) 8. Check the dirty filter indicators. Replace or clean filter elements as needed.

50

Hydraulic Fluid Care

Flushing the System If your system has more than one servovalve, replace one servovalve with a flushing valve or union. Remove the other servovalves and replace them with cover plates or plugs. WARNING

Residual pressure can produce a high pressure spray. You could be cut by this spray.

Do not start this procedure until all pressure gages read zero. 1. Identify and correct any sources of contamination. 2. Make sure that hydraulic system pressure is zero. 3. If you have an MTS Model 291.XX flushing valve, remove the servovalve from its manifold. Mount the flushing valve in its place. Remove any other servovalves. Cover any exposed servovalve ports with clean servovalve cover plates. If you do not have a flushing valve, remove the pressure and return lines from the servovalve manifold. Connect these lines together with a suitable union. Remove any other servovalves. Use threaded plugs to close any open ports. 4. On larger hydraulic distribution systems, cap all of the in-line accumulators. 5. Operate the HPS and at high pressure for 2 to 4 hours. (Run larger systems longer.) 6. Check the dirty filter indicators. Clean or replace filter elements as needed. 7. Turn off the HPS. Make sure that the hydraulic system pressure is zero. WARNING

Residual pressure can produce a high pressure spray. You could be cut by this spray.

Do not start this procedure until all pressure gages read zero.

Hydraulic Fluid Care

51

8. If you have used a flushing valve, remove the valve. Reinstall the servovalve. Reinstall any other servovalves that have been removed. If you have used a union, disconnect the union. Reconnect the hoses to the manifold. Reinstall any other servovalves that have been removed. 9. If you have capped in-line accumulators, uncap them. 10. Reconnect servovalve control cables. WARNING

Reapplying pressure with cables disconnected can cause violent actuator movement. You could be hurt and your equipment damaged.

Before reapplying pressure, make sure all control cables are routed to the right servovalve and firmly connected.

52

Hydraulic Fluid Care

Flushing the System with Solvent MTS recommends using MOBILSOL A solvent to flush and clean your hydraulic system. MOBILSOL A is designed to clean hydraulic systems of dirt and oxidation products and is compatible with Mobil DTE 25. Note

If your system has more than one servovalve, replace one servovalve with a flushing valve or union. Remove the other servovalves and replace them with cover plates or plugs.

1. Identify and correct any sources of contamination. 2. Make sure that hydraulic pressure is at zero. CAUTION

Solvents dislodge contaminants. Contaminants can plug servovalves, causing poor system performance.

Remove all servovalves before flushing.

WARNING

Residual pressure can produce a high pressure spray. You could be cut by this spray.

Do not start this procedure until all pressure gages read zero. 3. If you have an MTS Model 291.XX flushing valve, remove the servovalve from its manifold. Mount the flushing valve in its place. Remove any other servovalves. Cover any open ports with clean servovalve cover plates. If you do not have a flushing valve, remove the pressure and return lines from the servovalve manifold. Connect these lines together with a suitable union. Remove any other servovalves. Use threaded plugs to close any exposed ports. 4. On larger hydraulic distribution systems, cap the in-line accumulators. 5. Add the amount of solvent recommended by the solvent manufacturers to the HPS reservoir. (Typically 5% of hydraulic fluid volume.) 6. Operate the HPS at high pressure for 72 hours. 7. Turn off the HPS. 8. While the fluid is still hot, drain the HPS reservoir. As needed, wipe out the inside of the reservoir with clean cloths to remove any remaining contaminants. 9. Replace or clean the HPS filter elements.

Hydraulic Fluid Care

53

10. Fill the reservoir with clean hydraulic fluid. Use a transfer pump that can provide 10 micron or better filtration. 11. Operate the HPS at high pressure for two to four hours. (Run larger systems longer.) 12. Check the dirty filter indicators. Replace or clean filter elements as needed. 13. Turn off the HPS. Make sure that the hydraulic system pressure is zero. WARNING

Residual pressure can produce a high pressure spray. You could be cut by this spray.

Do not start this procedure until all pressure gages read zero. 14. If you have used a flushing valve, remove the valve. Reinstall the servovalve. Reinstall any other servovalves that have been removed. If you have used a union, disconnect the union. Reconnect the hoses to the manifold. Reinstall any other servovalves that have been removed. 15. If you have capped in-line accumulators, uncap them. 16. Reconnect servovalve control cables. WARNING

Reapplying pressure with cables disconnected can cause violent actuator movement. You could be hurt and your equipment damaged. Before reapplying pressure, make sure all control cables are routed to the right servovalve and firmly connected.

54

Hydraulic Fluid Care

Removing Water from Oil This procedure covers removing water from hydraulic fluid after a water-to-oil heat exchanger failure. When performing this procedure, keep these principles in mind: •

Water, in concentrations higher than 2% by weight, will separate from standing hydraulic fluid.

•

Water settles in low points in the hydraulic distribution system.

•

Water absorbing filters are available to remove water.

•

Water will evaporate from hydraulic fluid held at 82°C (180°F).

1. Isolate the HPS from the rest of the hydraulic distribution system. 2. Remove the damaged heat exchanger. Repair or replace it. 3. Allow time for the hydraulic fluid and water to separate. Draw any standing water off the bottom of the HPS reservoir. 4. Install water absorbing HPS filter elements. Circulate the hydraulic fluid to remove additional water. 5. As required, “boil off” water: A.

Remove the water control valve sensor from the HPS reservoir.

B.

Run the HPS.

C.

Manually control the heat exchanger’s water flow to maintain a reservoir temperature of 82°C (180°F) to boil off water.

6. Drain contaminated fluid from all low points in the distribution system. 7. If water contamination is less than 1%: A.

Circulate clean, “dry” fluid from the HPS throughout the distribution system.

B.

Use water absorbing filters throughout the distribution system to remove additional water.

C.

Repeat the “boiling off” procedure to remove water that accumulates in the HPS reservoir. If water contamination is severe, drain and discard the oil in the distribution system.

Hydraulic Fluid Care

55

Hydraulic Fluid Disposal Local, state, federal and international laws govern the disposal of hydraulic fluid. Many areas have businesses that specialize in fluid recovery for little or no cost. Check with the appropriate agency in your area for details on laws and services. Material Safety Data Sheets (MSDS) are available from Mobil or MTS. These sheets detail the fluid contents and in some areas are required by law. (Refer to the In-Plant Handling to Control Waste Oils Technical Bulletin available from Mobil.)

56

Hydraulic Fluid Care

HPS Startup in Special Circumstances After two-week shutdown

Fluid below 10°C

If the HPS has been shut down for two weeks or longer, do the following to allow the filters to collect contaminants: •

If the HPS is equipped with a circulating pump, run the circulating pump for about one hour before energizing the main pump.

•

If the HPS is not equipped with a circulating pump, run the HPS locally at low pressure for about one hour before applying full pressure and operating the system.

If the temperature of the HPS hydraulic fluid is below 10°C (50°F), do the following: •

If the HPS has a circulating pump, run this pump until the fluid temperature reaches 50°F (10°C) before energizing the main pump.

•

If the HPS does not have a circulating pump, run the HPS locally at low pressure for about one hour before applying full pressure.

Hydraulic Fluid Care

57

58

Hydraulic Fluid Care

Appendix C

Heat Exchanger Care Overview

Most HPSs (Hydraulic Power Supplies) manufactured by MTS are equipped with heat exchangers designed to remove 100% of the HPS heat load. Heat exchangers usually provide a long service life with little required maintenance because they have very few moving parts. However a heat exchanger failure can result in a costly and time-consuming cleanup, especially when your cooling water supply is mixed with hydraulic oil. Proper maintenance is essential to maintain a long life for your heat exchanger. The information in this appendix will help you get the longest possible service from your heat exchanger.

Contents

Types of Heat Exchangers

60

Heat Exchanger Operating Conditions

63

Major Components—Water-to-Oil Heat Exchanger Major Components—Air-to-Oil Heat Exchanger Water-to-Oil Exchanger Life Expectancy

61 62

65

Signs of Failure in a Water-to-Oil Heat Exchanger

66

Preventing Water-to-Oil Heat Exchanger Failures

67

Improving the Life of a Water-to-Oil Heat Exchanger

71

Water-to-Oil Heat Exchanger Maintenance Schedule Water-to-Oil Heat Exchanger Troubleshooting

73

77

Air-to-Oil Heat Exchanger Maintenance Schedule

78

Air-to-Oil Heat Inspection and Cleaning Procedure

79

Heat Exchanger Care

59

Types of Heat Exchangers A heat exchanger is a mechanical device that is used to transfer heat from one fluid to another. The amount of heat transferred is directly proportional to the temperature difference between the hydraulic fluid and the cooling medium. MTS uses water-to-oil and air-to-oil heat exchangers.

Water-to-oil

Water-to-oil heat exchangers (also called oil coolers) are used in locations where there is an ample supply of cooling water. These exchangers use heat transfer to cool hot oil by ing it over tubes filled with cooling water. The most common design is the shell and tube design. Hot oil circulates through a shell. Cooling water circulates through a tube bundle inside the shell. Baffles direct the hydraulic fluid at right angles to the tube bundle. Heat transfers from the hot hydraulic fluid to the cool water. Heat is then removed from the water by ing it through a cooling tower or an evaporation pond. Water-to-oil heat exchangers are available in many design variations. The straight tube design with a fixed tube bundle is used by MTS. These units are available with various baffle arrangements to create single or multiple heat exchangers. Multiple designs use less water and can be used more efficiently with less cost when colder circulating water is available.

Air-to-oil

60

Heat Exchanger Care

Air-to-oil heat exchangers (also called air coolers) are used in locations that do not have a sufficient water supply for cooling. These exchangers are similar to cooling systems used in automobiles. Hot oil es through tubes in radiator while air is blown across the radiator’s fins to remove the heat.

Major Components—Water-to-Oil Heat Exchanger Cool Oil Out Hub Shell Cooling Tubes

Hot Oil In

Baffles or Fins

End Bonnet Tube Sheet Cooling Water In

Cooling Water Out Zinc Anode (Optional) VW-G106

Mounting Bracket

Major Components—Two- Water-to-Oil Heat Exchanger A water-to-oil heat exchanger has the following major components: •

Shell—carries hot oil through the exchanger. It encloses the baffles very closely to prevent bying and ineffective flow areas. It is a seamless brass tube, with both ends welded into the hubs.

•

Cooling Tubes—carry cooling water through the exchanger. Tubes are usually made from copper, a copper-nickel alloy, or stainless steel. The tubes are accessible from either end for cleaning.

•

Tube Sheets—hold the cooling tubes in place. The brass tube sheets are bonded to the inside of the hubs.

•

Baffles or Fins—provide a area for dissipating heat. Baffles are made of brass.

•

Hubs—connect the shell to the end bonnets. Vents and drains are located on the underside of the brass forged hubs.

•

Bonnets—provide an unrestricted connection for cooling water flow. They are made of cast iron.

•

Zinc Anode—is replaceable and is used to prevent electrolytic damage.

Heat Exchanger Care

61

Major Components—Air-to-Oil Heat Exchanger

Oil In/Out Connection* Tubes and Fins

Motor and Fan

Oil In/Out Connection* Oil In/Out Connection*

*Connections vary between models. VW-G107

Major Components—One- Air-to-Oil Heat Exchanger An air-to-oil heat exchanger has the following major components:

62

Heat Exchanger Care

•

Tubes and Fins—are the major parts of the radiator. Hot oil circulates through the tubes in the radiator. Fins increase the radiator’s cooling surface.

•

Motor and Fan—blow cooling air through the radiator.

Heat Exchanger Operating Conditions Operating temperatures

HPS heat exchangers are typically designed for a minimum ambient operating temperature of 4°C (40°F) and a maximum ambient operating temperature of 40°C (104°F). A nameplate specifying specific operating pressures and temperatures is attached to each heat exchanger. The MTS Hydraulic Power Supply manual supplied with your system also contains specific information on operating pressures and temperatures for the heat exchanger supplied with your HPS.

Environment

Do not locate either an oil-to-water or an oil-to-air heat exchanger in a corrosive environment. Rapid deterioration of shells, radiators, motors, and fans may take place, shortening the exchanger’s operating life. Note

Water quality

The following items apply just to oil-to-water exchangers.

Water quality is critical for a successful water-to-oil heat exchanger system. Generally speaking, municipal drinking water available in developed countries is perfectly acceptable for copper tube heat exchangers. This water is clean, bacteriologically safe, and has a neutral pH. The Table below lists acceptable levels of compounds in cooling water. Acceptable Compound Levels in Cooling Water

COMPOUNDS

ALLOWABLE QUANTITY (PPM)

Ammonia

None

Bacteria

Must be bacteriologically safe

Calcium

<800 ppm

Chlorides

<5 ppm

Dissolved solids

>50 but <500 ppm; <150 ppm if abrasive solids are present

Iron

3 ppm

Nitrates

<10 ppm

Nitrogen compounds

None

Oxidizing salts or acids

None

pH level

6–8.5 (recommended)

Silica as SiO2

<150 ppm (to limit silica scale)

Chlorides

<5 ppm

Dissolved solids

>50 but <500 ppm; <150 ppm if abrasive solids are present

Iron

3 ppm

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Water from cooling towers, wells, rivers, and ponds must be free of pollutants and treated to limit contaminants to municipal drinking water levels. It is important to keep all contaminants within acceptable limits. Two contaminants in water can produce a corrosion rate a hundred times greater than could be caused by just one contaminant.

Softened and distilled water

Softened and distilled water can cause problems in water-to-oil heat exchangers. This water, though low in minerals, has higher than desirable levels of carbon dioxide and oxygen. High levels of carbon dioxide and oxygen will decrease the protective layer of minerals that form on the surface of the tubes and increase the formation of copper oxide.

Cooling tower water

Poorly maintained cooling tower water can cause rapid corrosion in a water-to-oil heat exchanger. The fans used on cooling towers can force air and organic pollutants into the water. Contamination levels in this water can vary seasonally and should be checked often. Contaminants in cooling tower water must be controlled to the levels listed in the above Table. Ideally, water pH should be maintained in the 6.5-8.5 range. Chlorine should be used to limit the growth of organisms. Do not use excessive amounts of chlorine. Keep the chloride level to less than 5 ppm. Cooling towers located in an industrialized area should be a closed-loop design to provide protection against airborne contaminants.

Additional help

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Local industrial water treatment specialists can provide additional information on your water conditions and solutions to contaminant problems.

Water-to-Oil Exchanger Life Expectancy Water-to-oil heat exchangers usually have a long service life and require little maintenance. Properly maintained, your heat exchanger could last up to 20 years. However, all heat exchangers have a finite service life and will fail sometime. Fouling and corrosion are the main causes of degraded performance and failure.

Fouling

Fouling builds up deposits that decrease a system’s thermal transfer rate and increase its flow resistance. As a result, the cooling water flow rate has to increase to keep the system at the same temperature.

Corrosion

Corrosion gradually wears away a component by mechanical or chemical action. Water-to-oil heat exchangers are usually constructed with corrosion-resistant copper or copper alloy tubes. A normal corrosion rate for these tubes is 5–25 µm per year. This implies an operating life of 20 years for your heat exchanger. Higher levels of contaminants in the cooling water will drastically shorten your exchanger’s operating life. Typically, corrosion causes these types of failure in a heat exchanger: •

Corrosive deposits block fluid flow in the heat exchanger tubing.

•

Corrosion causes water to leak into the hydraulic fluid or hydraulic fluid to leak into the cooling water supply. Both leaks result in costly repairs.

The type of contamination depends on the extent of the corrosion and the pressures of the hydraulic fluid and cooling water. Since fluid flows from a high pressure area to a low pressure area, the lower pressure fluid will become contaminated first. Eventually both the water and the hydraulic fluid will be contaminated as more leakage occurs.

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Signs of Failure in a Water-to-Oil Heat Exchanger Typical signs of failure in a water-to-oil heat exchanger are: •

Cloudy, milky hydraulic fluid. This indicates that water is leaking into the hydraulic fluid. Checking fluid color daily is a good way catch small leaks before they cause extensive damage.

•

Hydraulic fluid in the heat exchanger cooling water discharge. This indicates hydraulic fluid is leaking into the cooling water.

•

A hydraulic fluid analysis that shows a sharp rise in ppm (parts-per-million) copper levels. A slow steady rise over several analyses may not indicate a problem. A single analysis that shows a sharp rise means your heat exchanger will fail soon. The Table below lists copper levels and recommended actions. Copper Levels in Hydraulic Fluid

COPPER CONCENTRATION

INDICATION

20–50 (ppm)

Normal amounts

>50 (ppm)

Monitor analysis trends

Sharp rise

Take immediate action

Note

When to replace

To deal with contaminated hydraulic fluid, see the “Hydraulic Fluid Care” appendix. Refer to the “Hydraulic Fluid Maintenance Procedures.”

Replace or repair a heat exchanger at the first sign of failure. Most leaks start with a pinhole and then grow larger. Catastrophic failures can result in:

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•

A contaminated hydraulic distribution system

•

A contaminated water supply

•

Expensive repairs to your test system

•

Expensive cleanups supervised by an environmental protection agency

•

Extensive lost testing time

Preventing Water-to-Oil Heat Exchanger Failures This section discusses four common types of failure in water-to-oil heat exchangers and how to prevent them.

Mechanical failures Metal erosion

These failures result from metal erosion, water hammer, vibration fatigue, thermal fatigue, and freeze up. Excessive fluid velocity on either the shell or tube side of the heat exchanger can cause damaging metal erosion. Corrosion accelerates as metal erosion removes protective films, exposing fresh metal to further attack. Most metal erosion problems occur inside the tubes, with tube entrance areas most prone to erosion. These areas have severe metal loss when high-velocity water enters the exchanger and divides into much smaller streams. This results in turbulence with very high localized velocities. The maximum recommended water velocity in the tubes and entrance nozzle depends on the tube material and water quality. Stainless steel and copper-nickel tubes can withstand tube velocities of 3.0–3.4 m/s (10–11 ft/s). Velocities for copper tubes are normally limited to 2.3 m/s (7.5 ft/s). Velocities for copper tubes should be less if the cooling water is softened or contains suspended solids.

Water hammer

Water hammer is the sound produced by damaging surges in water pressure and flow. To reduce water hammer, always start the flow of cooling water through the exchanger when you turn on the HPS. Fluid flow control valves that open or close suddenly can produce water hammer. Modulating control valves are preferred to on-off types.

Vibration fatigue

Excessive equipment vibration and pulsating transients in the fluid flow can cause tube failures. Failures appear as fatigue stress cracks or erosion of tubing at baffle points. To prevent this type of failure, isolate heat exchangers from excessive vibration.

Thermal fatigue

Repeated thermal cycling can cause tubing failure. In thermal fatigue, temperature changes cause tube flexing. This produces a stress that acts cumulatively until the tube cracks. The crack usually runs radially around the tube and many times results in a total break. A thermostatic or spring-loaded by relief valve installed ahead of the heat exchanger will hasten warm-up and relieve excessive pressures. It can also control the oil temperature in certain installations.

Freeze up

Freeze up occurs when cooling water in the heat exchanger freezes. Common causes are failing to provide thermal protection, a broken thermal protection system, not draining cooling water before winter shutdown, or not enough antifreeze.

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Corrosion failures

General corrosion

Chemically induced corrosion failures result from general corrosion, pitting, stress corrosion, de-zincification, galvanic corrosion, and crevice corrosion. General chemical corrosion is characterized by a slow, uniform attack on the tube, tube sheet, or shell, with little or no evidence that corrosion is taking place. For copper, low cooling water pH (less than 7) combined with carbon dioxide or oxygen produces corrosion. A blue or bluish-green color on the tubes shows the results of carbon dioxide attack on the inside of a copper tube. Various chemicals, such as acids, also produce this type of metal loss. You can reduce general corrosion and maximize the life of your heat exchanger by selecting a material with adequate corrosion resistance for the operating environment and by using the proper treatment chemicals to clean and protect the components of your heat exchanger.

Pitting

Localized pitting is frequently encountered in metals. It is caused by the electrochemical potential set up by differences in the concentration of oxygen inside and outside the pit and is frequently referred to as a concentration cell. The oxygen-starved pit acts as an anode and the unattacked metal surface as a cathode. A small number of pits may be present and any one can cause a heat exchanger failure. Pitting corrosion can occur during shutdown periods when still cooling water creates an environment suitable for the buildup of concentration cells. Scratches, dirt or scale deposits, surface defects, breaks in protective scales and metal surface films, and grain boundary conditions increase the susceptibility of the metal to pitting corrosion.

Stress corrosion

Stress corrosion attacks the grain boundaries (changes in the crystalline structure of the metal) in stressed areas. Manufacturing processes produce stressed areas in heat exchanger tubes. Stress corrosion failures appear as fine cracks, following the lines of stress and material grain boundaries. High levels of chloride ions in cooling water will cause stress corrosion. All naturally occurring waters contain chloride ions. They are also potentially present in any compound formulated with chlorine. Keeping chloride ion concentrations below 50 ppm and tube wall temperatures below 52°C (125°F) will reduce stress corrosion problems. Even very small concentrations of ammonia in cooling water can cause stress corrosion on copper or copper alloy tubes. 1 ppm or less can cause problems. Copper-nickel alloys have good resistance to stress corrosion and should be used in applications where concentrations of ammonia are expected.

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De-zincification

De-zincification occurs when a copper-zinc alloy containing less than 85% copper s cooling water with a high oxygen and carbon dioxide content. Zinc is chemically removed from the alloy, leaving a porous surface. The remaining copper has a sponge-like appearance. Increased temperatures and water with pH below 7 accelerates de-zincification. It can be prevented by using brass with lower zinc content or brass containing tin or arsenic to inhibit the chemical action or by controlling the environment causing the problem.

Galvanic corrosion

This type of corrosion occurs when dissimilar metals are ed in the presence of an electrolyte, such as acidic water. Galvanic corrosion usually produces a higher rate of reaction on the more chemically active metal.

Crevice corrosion

This type of corrosion originates in and around hidden and secluded areas, such as between baffles and tubes or under loose scale and dirt. Relatively stagnant conditions must exist for crevice corrosion to occur. A localized cell develops and the resulting corrosion appears as a metal loss with local pits, often giving the impression that erosion is taking place. This contrasts with a vibration failure where the metal is sharply cut and there are no pits. Crevice corrosion can often be controlled by keeping fluid flow velocities adequate to prevent stagnation or the accumulation of solids.

Combined failures

Combined failures result from a combination of mechanical erosion with chemical corrosion or chemical corrosion with mechanical fatigue.

Erosion-corrosion

Erosion-corrosion combines mechanical erosion with chemical corrosion to produce failure. Mechanical erosion caused by excessive fluid velocity, suspended solids, or mechanical vibration will erode away protective films and accelerate chemical corrosion. Erosion-corrosion is usually found in the entrance area of tubes, below the shell inlet nozzle, and at the point of with baffles and tubes.

Corrosion-fatigue

Corrosion-fatigue combines chemical corrosion with mechanical fatigue to produce failure. In most environments, corrosion produces protective films that retard corrosive attack. In corrosion-fatigue, mechanical stresses such as vibration, temperature cycles, and water hammer strip away this protective film. The exposed area has an accelerated chemical corrosion rate.

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Fouling failures

Fouling failures result from accumulations of scale, suspended solids, mud, and algae.

Scale

Dissolved minerals precipitating from the cooling water create scale. Heat exchanger temperature changes and chemical reactions between compounds in the water affect the solubility of these minerals. MTS designed your HPS to have an optimum fluid velocity based on your system’s heat transfer needs and the tube material used. This velocity should keep the precipitation rate low. Fouled or clogged tubes will decrease the fluid velocity and increase the precipitation rate. Regularly clean the tubes and inlet filters to keep the fluid velocity high enough to inhibit scaling.

Suspended solids

Suspended solids are visible particles of silt, iron, and sand found in both cooling water and hydraulic fluid. They will settle out and build up on the tube walls if fluid velocities are not high enough. They are very abrasive to heat exchanger parts. Proper use of filters and screens for the cooling water and hydraulic fluid will reduce the amount of suspended solids.

Algae

Algae and other marine growths are a serious problem once established in a heat exchanger. A heat exchanger can be an excellent environment for their rapid growth, which will restrict cooling water flow and impede heat transfer. Chemical algaecides, such as chlorine, are effective in controlling algae and other marine growths. High fluid velocities will keep them from proliferating.

Heat Exchanger Care

Improving the Life of a Water-to-Oil Heat Exchanger This section discusses four ways to extend the life of a heat exchanger:

Choose the right tubing

•

Choose the right tubing material for your water conditions

•

Keep the cooling water supply clean

•

Monitor the cooling water flow rate

•

Protect the heat exchanger during shipping and storage

While you cannot prevent corrosion from occurring in your heat exchanger, you can reduce the corrosion rate by selecting the appropriate materials for your heat exchanger. MTS can assist you in selecting the proper tubing for your heat exchanger based on an analysis of your water supply. The standard material used in heat exchanger tubes is 99.9% pure soft copper. Copper-nickel (CuNi), an alloy of copper that has 10% nickel, offers a high resistance to corrosion caused by many common pollutants. A 90–10 copper alloy tube has a corrosion rate typically one-half to one-third that of pure copper and adds 20–25% to the heat exchanger’s cost. It is a good solution for mildly corrosive water (typical of water taken from a ground water supply). It is not a solution to severe corrosion problems that may occur when cooling towers are used. Adding zinc anodes to the heat exchanger bonnet can make heat exchangers last longer. Most copper-nickel heat exchangers can be furnished with anodes. These anodes screw into the bonnet and protect the tube sheet and bonnet metal against de-zincification corrosion. The anodes will corrode before the copper alloy tubes in most cases. Regularly inspect and replace anodes to maintain protection against de-zincification. If you have a saltwater cooling water supply, MTS recommends using tubes and tube sheets made of 90–10 copper-nickel and bonnets made of bronze. Zinc anodes also should be used to reduce the corrosion rate.

Keep the water clean

Contaminants suspended in the cooling water supply can clog heat exchanger tubes. This will decrease the heat exchanger’s efficiency and can cause damaging erosion or corrosion to the tubes. To prevent sediment buildup in the tubes, install a filter or strainer in the cooling water inlet to prevent large particles from entering the tubes. MTS recommends that water strainers be installed ahead of the heat exchanger if the cooling water source contains large amounts of particles or sediment. Note

Strainers provide little corrosion protection since most corrosives are dissolved rather than suspended solids.

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Monitor the flow rate

Keeping sufficient cooling water flow in all the tubes is the easiest way to prevent fouling. Sufficient flow creates a self-cleaning effect in the tubes, helping them retain to their heat transfer characteristics. If you notice a decrease in your heat exchanger’s efficiency, inspect the filter, strainer, and tubes for signs of fouling. Install a pressure relief or regulating valve to protect the exchanger from bursting pressures if there is a possibility of water pressure surges above the heat exchanger’s design pressure.

Shutdown protection

MTS flushes heat exchanger tubes with Dow Chemical Dowfrost HD antifreeze to prevent corrosion during shipment and short-term storage. Dowfrost HD is a propylene glycol heat transfer fluid used in closed loop HVAC (Heating Ventilation and Air Conditioning) systems. The HD designation means it will work with the different metals in heat exchangers. It has excellent anti-corrosion properties and low toxicity. MTS warns against using ethylene glycol flushing solutions, which can be very corrosive under certain conditions. If your heat exchanger is to be shut down for a period of time (weeks or months), MTS recommends that you drain the heat exchanger and flush it with a corrosion-preventive fluid. Seal the shell and bonnet openings to prevent dirt from entering. If ambient temperatures will drop below 0°C (32°F), always drain cooling water from the heat exchanger to prevent frost damage.

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Water-to-Oil Heat Exchanger Maintenance Schedule Use the following as a guide in maintaining your heat exchanger. Your operating environment may require more frequent maintenance. Prompt action on warning signals is the best preventive measure.

On arrival

During installation

8 hours/daily

When the HPS arrives at your test site, check the following on the heat exchanger: •

Inspect the exchanger for shipping damage.

•

Inspect the water line connections to make sure no dirt has entered the exchanger.

•

Check the tightness of the bolts holding the shell together.

•

Make sure the heat exchanger is solidly mounted in place.

During installation, take care when using sealing tape on pipe threads. Tape acts as a thread lubricant, which can lead to over-tightening and cracked castings. Daily or after every eight hours of operation, do the following: 1. Check the fluid level in the HPS reservoir sight glass: A low level can indicate a hydraulic fluid leak into the heat exchanger. A high level can indicate a water leak from the heat exchanger. 2. Check the hydraulic fluid for signs of water contamination: When the system is running, look at the HPS reservoir sight glass. Water gives the fluid a cloudy, milky appearance. When the system is not running, draw off a fluid sample from the bottom of the reservoir. Water will appear in your sample.

500 hours/3 months

Every 3 months or after every 500 hours of operation or when you notice a decrease in exchanger performance, do the following (favorable operating conditions can extend this interval up to one year or 2000 hours): 1. Inspect the exchanger externally and internally. Refer to the “Inspect the Heat Exchanger” procedure that follows. 2. Mechanically clean the exchanger if your inspection finds light scale and sediment in the tubes. 3. Chemically clean the exchanger if your inspection finds heavy calcium deposits in the tubes.

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Inspect the Heat Exchanger 1. Shut off the HPS. Shut off the cooling water supply. 2. Externally inspect the exchanger for: –

Dents, bulges, and leaks

–

Damaged gaskets

–

Corrosion

–

Worn, frayed, and leaking hoses

3. Drain all hydraulic fluid from the heat exchanger. Drain all water from the exchanger. 4. Clean all filters and screens. 5. Remove the end bonnet from the water intake side of the heat exchanger. (If you have to remove a mounting bracket, use blocks of wood to the exchanger.) Note

Be careful when you handle a removable tube bundle. Bending the bundle’s baffle plates will let hydraulic fluid by the tube surfaces, decreasing exchanger efficiency. Clean out the tubes with a nylon bristle brush. Metal bristles will scratch the tubes, accelerating corrosion.

6. Internally inspect the exchanger for: –

Corrosion and erosion damage to the tubes and tube ends

–

Fouling and corrosion deposits on the tubes

–

Condition of the optional zinc anodes

–

Damaged threads

7. If your exchanger has optional anodes, de-scale and inspect them. Replace them as needed. 8. If no further cleaning is needed, reassemble the heat exchanger using new gaskets. If further mechanical or chemical cleaning is needed, continue on to the following “Mechanically Clean the Heat Exchanger” and “Chemically Clean the Heat Exchanger” procedures.

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Mechanically Clean the Heat Exchanger Continue on with this procedure if internal and external inspection finds light scale and sediment on the tubes. 1. As needed, remove the heat exchanger from the HPS. 2. Complete the disassembly of the heat exchanger. 3. Clean out the tubes with a nylon bottle brush. 4. Clean the remaining heat exchanger parts. 5. Carefully inspect all parts for signs of failure. Replace parts as needed. 6. Reassemble the heat exchanger using new gaskets.

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Chemically Clean the Heat Exchanger Continue on with this procedure if your internal inspection finds heavy calcium deposits on the tube. WARNING

Cleaning solvents are caustic. They can burn your eyes and skin. Their vapors can burn your lungs. Always follow the manufacturer’s safety precautions when using solvents.

1. As needed, remove the heat exchanger from the HPS. 2. Complete the disassembly of the heat exchanger. 3. Clean the tubes by flushing them with a 15% solution of inhibited muriatic (hydrochloric) acid in water. The system must be open to vent gases. The amount of scale determines the length of time required for flushing. For 1 mm (0.04 in.) thick scale, flush the tubes for about 30 minutes. 4. Drain the tubes completely. Thoroughly flush the tubes with clean water. 5. Flush the tubes with a neutralizing agent, such as a 5% sodium carbonate solution. Drain the tubes completely. Thoroughly flush the tubes with clean water. 6. Repeat steps 3–5 of this procedure in the opposite flow direction. 7. Clean the remaining heat exchanger parts. 8. Use a solvent to remove any oil residues. 9. Carefully inspect all parts for signs of failure. Replace parts as needed. 10. Reassemble the heat exchanger using new gaskets.

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Water-to-Oil Heat Exchanger Troubleshooting Water-to-Oil Heat Exchanger Troubleshooting SYMPTOM

CORRECTIVE ACTION

Fluid in reservoir overheats

the proper water connections: IN—>IN OUT—>OUT that the water temperature versus flow rate is correct for your model of HPS (refer to the MTS Hydraulic Power Supply manual that came with your system). that the water saver valve is operating correctly. Adjust it if necessary (refer to the instructions in the MTS Hydraulic Power Supply manual).

Plugged heat exchanger tubes

Perform a mechanical cleaning. Perform a chemical cleaning as needed. Install a filter in the cooling water inlet line to prevent the buildup of sediment. Make sure your cooling water is clean.

Cloudy hydraulic fluid or fluid in the cooling water discharge (heat exchanger internal leakage)

Disassemble the heat exchanger. Pressure test to find the leak. Repair or replace the heat exchanger.

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Air-to-Oil Heat Exchanger Maintenance Schedule Use the following as a guide in maintaining your air-to-oil heat exchanger. Your operating environment may require more frequent maintenance. Prompt action on warning signals is the best preventive measure.

On arrival

During installation

8 hours/daily

When the HPS arrives at your test site, check the following on the heat exchanger: •

Inspect the exchanger for shipping damage.

•

Make sure the fan turns freely.

•

Make sure the heat exchanger is solidly mounted in place.

During installation, take care when using sealing tape on pipe threads. Tape acts as a thread lubricant, which can lead to over-tightening and cracked castings. Daily or after every eight hours of operation, do the following: 1. Check the fluid color and level in the HPS reservoir sight glass: –

A low level can indicate a hydraulic fluid leak in the heat exchanger.

–

A dark color, along with a burnt smell, can indicate that the heat exchanger is not keeping the fluid cool.

2. Check that nothing obstructs air flow through the radiator.

500 hours/3 months

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Every 3 months or after every 500 hours of operation or when you notice a decrease in exchanger performance, perform the following “Air-to Oil Exchanger Inspection and Cleaning” procedure.

Air-to-Oil Heat Inspection and Cleaning Procedure 1. Shut off the HPS. 2. Inspect the heat exchanger for: –

Loose bolts

–

Worn, frayed, and leaking hoses

–

Corrosion

–

Obstructions blocking the flow of air through the radiator

–

Damaged or leaking radiator fins and tubes

3. As needed, use a brush or compressed air to clean the radiator fins and tubes. If the radiator is greasy, remove the motor assembly. Spray or brush the radiator fins and tubes with a mild alkaline solution or a nonflammable degreasing fluid. Then rinse with hot water and dry thoroughly. A steam hose is also effective in removing grease. 4. Remove dirt and grease from the heat exchanger casing. Sand and repaint rusty or corroded surfaces. 5. Clean the fan motor and fan blade of dirt and grease. 6. Some fan motors may have grease zerks. Lubricate the fan motor as needed. Follow the instructions attached to the motor.

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