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2202MYJE-MY-C8-N_2018.02.

Compound 2-stage Screw Compressor

3225 * * C Instruction Manual

3225LLLC/3225LLMC/3225LLSC/3225LLC/3225LMC/3225LSC

3225MLC/3225MMC/3225MSC/3225SLC/3225SMC/3225SSC

CAUTION

Before operating, servicing, or inspecting this product, read this manual thoroughly to fully understand the contents. Keep this Instruction Manual in a safe, designated place for future reference whenever the manual is needed.

Specifications of this product and contents of this manual are subject to change without prior notice due to technical improvements, and the like.

2202MYJE-MY-C8-N_2018.02.

Preface

Compound 2-stage Screw Compressor 3225**C

Preface

Thank you for purchasing the C-series compound 2-stage screw compressor 3225**C (hereinafter referred to as "this product").

This Instruction Manual (hereinafter referred to as "this manual") provides safety information and operation and maintenance procedures, so that users correctly understand how to handle this product and, as a result, can use it safely and efficiently. This manual is applicable to the following models:

3225LLLC-*B*-51

3225LLLC-*B*-61

3225LLMC-*B*-51

3225LLMC-*B*-61

3225LLSC-*B*-51

3225LLSC-*B*-61

3225LLC-*B*-51

3225LLC-*B*-61

3225LMC-*B*-51

3225LMC-*B*-61

3225LSC-*B*-51

3225LSC-*B*-61

3225MLC-*B*-51

3225MLC-*B*-61

3225MMC-*B*-51

3225MMC-*B*-61

3225MSC-*B*-51

3225MSC-*B*-61

3225SLC-*B*-51

3225SLC-*B*-61

3225SMC-*B*-51

3225SMC-*B*-61

3225SSC-*B*-51

3225SSC-*B*-61

* -51 (-61) may not be written. For more information, see 2.2 "Model designation of the compressor" in this manual Chapter 2.

Make sure you read this manual before installing or using this product. Keep this manual in a safe place near this product for quick reference.

Revision History

Title

Document No.

First edition issue date

3225**C Instruction Manual

2202MYJE-MY-C8-N_2018.02.

Nov. 14, 2014

Revision

No.

Issue date

Major Contents of revisions

Created/approved by:

Nov. 14, 2014

Overall review associated with reissue as electronic document, document No. change

Ikehara / Hirao

Apr. 30, 2015

Modified the constitution of Chapter 4 and Chapter 5. Correction of describing, etc.

Ikehara / Muta

Feb.28.2018

Corrected Table 2-1&2-2, Figure 2-1～12, Table 7-1&7-2. Corrected other errors. Deleted Contact Information

Takenouchi・Ito/Kato

2202MYJE-MY-C8-N_2018.02.

Warranty and Disclaimer

Compound 2-stage Screw Compressor 3225**C

Warranty and Disclaimer

Warranty

MAYEKAWA shall repair or replace parts of this product for no charge if any failure resulting from defects in design or manufacture occurs, under normal use with the purpose and method that are in accordance with the specifications of this product and this manual, within the warranty period.

The warranty period is "12 months from factory shipment of this product". If there is a separate agreement, that agreement shall prevail in principle.

MAYEKAWA is not liable for production or man-made disaster compensation due to malfunction or damage of this product.

Disclaimer of Warranty

Although MAYEKAWA warrants the clauses mentioned above, the following clauses are exempted.

 Malfunction or damage of this product caused by natural disaster, or other accidental forces

(such as fire, thunderbolt, windstorm, intense rainfall, flood, tidal wave, earthquake, land subsidence, etc.).

 Malfunction or damage caused by misusage described below.

 Malfunctions, damage, or deterioration of this product due to abnormal or improper use

(including improperly storing this product outdoors or under too hot/humid conditions, unexpected inspections, tests, operations, too frequent liquid flow-back operation*, and too frequent start-stop cycles, etc.).

 Malfunction or damage caused by devices or equipments not provided by MAYEKAWA

including operation control methods of those devices.

 Malfunction or damage caused by refrigerants, gases, or refrigerant oils, and operating

conditions (design conditions) not approved for this product.

 Malfunction or damage caused by maintenance or inspection not recommended by

MAYEKAWA.

 Malfunction or damage caused by parts that are not genuine.  Malfunction or damage caused by remodeling the product without approval of

MAYEKAWA.

 Malfunction or damage caused by unexpected misusage

"Liquid flow-back operation" is ･･･ Normally, while the compressor sucks in the refrigerant liquid only after vaporizing it in the

evaporator, it may directly sucks it in because of the faulty adjustment or failure of the expansion valve. We call this state of compressor operation "liquid flow-back operation".

No compressor can compress a liquid. The compressor may be damaged should the liquid be sucked in.

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Important Information

Compound 2-stage Screw Compressor 3225**C

iii

Important Information

Intended Use of This Product

This product is a general-purpose screw compressor for refrigeration, cold storage and various gases compression. Do not use this product for any other purposes that are not intended for or which depart from the specifications. For specifications of this product, refer to "2.3 Compressor Specifications".

Please perform the maintenance items described in this manual by using safe and assured procedures.

For Safe Use of This Product

Although MAYEKAWA has paid a lot of attention to safety measures for this product, all hazards including potential hazards caused by human errors, or due to environmental conditions can not be anticipated.

As there are too many items to be strictly observed or prohibited when using this product, it is impossible to inform all of them through this manual. Therefore, when operating this product, pay extreme caution on personnel safety as well as on items described in this manual.

Important rules for safety work with this product that apply to all workers including managers and supervisors are listed below.

Please read this manual before using this product. Fully understand the instructions provided there, and be sure to perform the safety procedures described in this manual.

 Operation, maintenance, and inspection of this product should be performed by qualified

personnel educated about the fundamentals of this product and trained about hazards involved and measures to avoid danger.

 Do not allow any person other than those educated on the fundamental expertise of this

product and trained about hazards involved and measures to avoid dangers to approach this product while it is operating or during maintenance.

 Observe all related federal/national and local codes and regulations.  To prevent accidents, do not carry out any operation or maintenance other than those

described in this manual. Do not use this product for any purpose other than intended.

 Replace the parts with genuine parts.  Not only workers but also managers should actively participate safety and health activities in

the workplace to prevent accidents.

 When closing or opening a valve during work, make sure to apply lockout/tagout to prevent

the valve from being accidentally closed or opened during the work.

[Lockout] To lock with a key in order to keep people, except the workers involved, from

operating the product.

Lockout means disconnecting or keeping disconnected machines and devices by locking their energy

(power) sources. Lockout is not just simply turning off the power switches to stop the supply of power, but includes immobilizing them with a key or similar device to keep any blocked switches from being operated.

Lockout devices are devices such as keys, covers, and latches, to immobilize switches, valves, opening and closing levers, etc., with a state of being locked.

[Tagout] To prevent any inappropriate work by hanging tag plates indicating "work in progress".

Tagout means to clearly indicate, by hanging tag plates, that a device is in lockout and that operation of the device is prohibited. Tag plates forbidding operation, starting, opening, etc. are warnings clearly stating to not operate energy (power) sources, and are not for stopping blocking devices.

2202MYJE-MY-C8-N_2018.02.

Important Information

Compound 2-stage Screw Compressor 3225**C

Observe the following precautions when performing maintenance work on electrical control.

 Electrical maintenance of the product must be performed by certified/qualified personnel and

only those educated about the electrical control of the product.

 Before servicing or inspecting the electrical equipment or devices, turn "OFF" the motor main

power and control power, and perform lockout/tagout to prevent the power from being turned on during work.

Even when the motor main power and control power are turned "OFF", this product may be turned on if the power is supplied from outside the package unit. Make sure the power supply on the power source side is shut off, and perform lockout/tagout to prevent the product from being turned on during work.

About This Manual

 This product may be modified without prior notice. Therefore, the appearance of actual

machine may differ from the descriptions in this manual. If you have any questions, contact our sales offices or service centers. For each sight of MAYEKAWA, refer to following URL. http://www.mayekawa.com/about/network/

 This manual is in English. If any other language is required, it is the customers’ responsibility

to prepare a manual for safety education and operation instructions.

 This manual is copyrighted. Drawings and technical references including this manual shall not,

in whole or part, be copied, photocopied, or reproduced into any electronic medium or machine-readable form without prior permission from MAYEKAWA.

 Photographs or drawings included in this manual may differ from the appearance of actual

product.

 If this manual is lost or damaged, immediately request our local sales offices or service

centers for a new manual. Using this product without the manual may result in safety issues.

 If you resell this product, never fail to attach this manual to this product.

Construction of This Manual

Title of section and chapter

Description details

Preface

Describes the outline of this manual and how to read this manual.

Warranty and Disclaimer

Describes what MAYEKAWA warrants and what are covered by the warranties. Warranty exemption is stated as disclaimer.

Important Information

Describes important information related to this product and this manual.

1. Safety

Describes safety information for the worker, safety rules for this product, and management details regarding the work safety that is required for handling this product.

2. Compressor Specifications and Structure

Describes the main components of this product, functional information, specification, and operating limits.

3. Installation

Describes the installation procedure of this product.

4. Compressor and Package Unit Operation

Describes the precautions for operating this product.

5. Maintenance and Inspection

Describes sections and period for inspecting, and assembly and disassembly of this product.

6. Troubleshooting

Describes troubleshooting methods for this product in case problems occur during operation of this product.

7. Related Documents

Describes documents such as exploded views and parts list.

2202MYJE-MY-C8-N_2018.02.

Table of Contents

Compound 2-stage Screw Compressor 3225**C

Table of Contents

Preface .................................................................................................................... ⅰ

Revision History ..................................................................................................... ⅰ

Warranty and Disclaimer ....................................................................................... ⅱ

Important Information ............................................................................................ ⅲ

Intended Use of This Product ........................................................................................... ⅲ

Important Information for Safe Use of This Product .......................................................... ⅲ

About This Manual ............................................................................................................. ⅳ

Construction of This Manual .............................................................................................. ⅳ

Table of Contents ................................................................................................... ⅴ

Chapter 1 Safety

1.1 Strict Requirements and Prohibitions ........................................................ 1-1

1.1.1 Strict Requirements (Do’s)................................................................................... 1-1

1.1.1.1 Do’s on Operation ........................................................................................ 1-1

1.1.1.2 Do’s on Maintenance ................................................................................... 1-1

1.1.1.3 Do’s on Lockout/Tagout after Shutting Off the Power ................................. 1-1

1.1.1.4 Do’s about Personal Protective Gear .......................................................... 1-2

1.1.1.5 Do’s about Handling of Hazardous and Toxic Substances .......................... 1-2

1.1.1.6 Do’s about Handling Emergency Situations ................................................ 1-2

1.1.1.7 Do’s about Waste Oil, Fluid, and Materials ................................................. 1-2

1.1.1.8 Other Do’s .................................................................................................... 1-3

1.1.2 Prohibitions (Don’ts) ......................................................................................... 1-3

1.2 Warnings ....................................................................................................... 1-3

1.3 Residual Risks ............................................................................................. 1-4

1.4 Safety Devices .............................................................................................. 1-6

1.4.1 Emergency Stop Button ....................................................................................... 1-6

1.4.2 Breakers of motor main power and control power

(with Lockout/Tagout Mechanism) ...................................................................... 1-6

1.4.3 Compressor Protective Devices .......................................................................... 1-7

Chapter 2 Compressor Specifications and Structure

2.1 Overview of the 3225**C ............................................................. 2-1

2.2 Model Designation of the Compressor ................................................... 2-1

2.3 Compressor Specifications ........................................................................ 2-2

2.3.1 Standard Specifications ....................................................................................... 2-2

2.3.2 Operation Limits ................................................................................................... 2-4

2.3.3 Outer Dimensions ................................................................................................ 2-5

2.4 Structure of Compressor .......................................................................... 2-17

2.4.1 Sectional View ................................................................................................... 2-17

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Table of Contents

Compound 2-stage Screw Compressor 3225**C

2.5 Mechanisms ............................................................................................... 2-18

2.5.1 Basics of the Screw Compressor ...................................................................... 2-18

2.5.2 Suction Process ................................................................................................. 2-18

2.5.3 Compression Process ........................................................................................ 2-19

2.5.4 Discharge Process ............................................................................................. 2-19

2.5.5 About Volume Ratio (Vi) .................................................................................... 2-19

2.5.6 Capacity Control Mechanism ............................................................................. 2-21

2.5.7 Bearings and Balance Piston ............................................................................ 2-21

2.5.8 Shaft Seal Block ................................................................................................ 2-21

2.6 Gas and Oil Flow ........................................................................................ 2-22

Chapter 3 Installation

3.1 General Precautions for Installation .......................................................... 3-1

3.2 Installation Works ........................................................................................ 3-1

3.2.1 Unpacking ............................................................................................................ 3-1

3.2.2 Storage ................................................................................................................ 3-1

3.2.3 Transportation ...................................................................................................... 3-1

3.2.4 Preparation for Installation ................................................................................... 3-4

3.2.5 Installation ............................................................................................................ 3-5

3.2.5.1 Installation .................................................................................................... 3-5

3.2.5.2 Shaft Alignment between the Compressor and Driving Machine ................ 3-5

3.2.5.3 Piping Connection ....................................................................................... 3-6

3.2.5.4 Equipment and Devices for Protection of the Compressor ......................... 3-6

3.2.6 Airtightness Test .................................................................................................. 3-7

3.2.7 Lubricating Oil Charge ......................................................................................... 3-7

3.2.7.1 Initial Charge of Lubricating Oil ................................................................... 3-7

3.2.7.2 Additional Charge of Lubricating Oil ............................................................ 3-7

3.2.8 Charge of Refrigerant .......................................................................................... 3-7

3.2.9 Check after Installation ........................................................................................ 3-7

Chapter 4 Compressor and Package Unit Operation

4.1 Lubricating Oil (Refrigerant Oil) ................................................................. 4-1

4.1.1 Precautions for Selecting the Lubricating Oil....................................................... 4-1

4.1.2 Recommended Lubricating Oils .......................................................................... 4-1

4.1.2.1 Recommended Lubricating Oils for Ammonia Refrigerant .......................... 4-1

4.1.2.2 Oils for systems using Hydrofluorocarbon refrigerants ............................... 4-2

4.1.3 Change of Lubricating Oil Brand ......................................................................... 4-3

4.1.4 Precautions for Handling lubricating Oil .............................................................. 4-4

4.1.5 Lubricating Oil Management Criteria ................................................................... 4-5

4.1.6 Lubricating Oil Replacement Timing .................................................................... 4-6

4.1.6.1 After Starting the Initial Operation ............................................................... 4-6

4.1.6.2 During Normal Operation............................................................................. 4-6

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Compound 2-stage Screw Compressor 3225**C

vii

4.2 Precautions for Operation ........................................................................... 4-7

4.2.1 Prevention of Liquid Flow-back Operation ........................................................... 4-7

4.2.2 Purging of Non-Condensable Gases ................................................................... 4-7

4.3 When Stopping the Compressor for a Long Time .................................... 4-8

Chapter 5 Maintenance and Inspection

5.1 Precautions for Maintenance and Inspection ............................................ 5-1

5.2 Maintenance and Inspection List................................................................ 5-3

5.2.1 Daily Management ............................................................................................... 5-3

5.2.2 Periodic Inspection .............................................................................................. 5-5

5.2.3 Guidelines for the Timing of Compressor Overhaul ............................................ 5-6

5.3 Compressor Disassembly Preparation ...................................................... 5-7

5.3.1 Disassembly Tools and Workplace ..................................................................... 5-7

5.3.2 Replacement Parts .............................................................................................. 5-8

5.3.3 Refrigerant Gas Recovery ................................................................................. 5-11

5.3.4 Removal of Connections to the Unit .................................................................. 5-12

5.3.5 Removal and Lifting the Compressor ................................................................ 5-13

5.3.6 Draining Oil from the Compressor ..................................................................... 5-13

5.4 Disassembly and Inspection ..................................................................... 5-14

5.4.1 Unloader Indicator ............................................................................................. 5-15

5.4.1.1 Disassembly .............................................................................................. 5-15

5.4.1.2 Inspection .................................................................................................. 5-17

5.4.2 Unloader Cover .................................................................................................. 5-18

5.4.2.1 Disassembly .............................................................................................. 5-18

5.4.2.2 Inspection .................................................................................................. 5-19

5.4.3 Unloader Piston and Unloader Cylinder ............................................................ 5-20

5.4.3.1 Disassembly .............................................................................................. 5-20

5.4.3.2 Inspection .................................................................................................. 5-21

5.4.4 Shaft Seal Block ................................................................................................ 5-22

5.4.4.1 Disassembly .............................................................................................. 5-22

5.4.4.2 Inspection .................................................................................................. 5-23

5.4.5 Bearing Cover .................................................................................................... 5-24

5.4.5.1 Disassembly .............................................................................................. 5-24

5.4.6 Separating High-stage and Low-stage Blocks................................................... 5-25

5.4.6.1 Disassembly .............................................................................................. 5-25

5.4.7 Gear Coupling .................................................................................................... 5-25

5.4.7.1 Disassembly .............................................................................................. 5-25

5.4.7.2 Inspection .................................................................................................. 5-26

5.4.8 Removing Oil Injection Pipe............................................................................... 5-27

5.4.8.1 Disassembly ............................................................................................... 5-27

5.4.9 Balance Piston ................................................................................................... 5-28

5.4.9.1 Disassembly .............................................................................................. 5-28

5.4.9.2 Inspection .................................................................................................. 5-28

5.4.10 High-stage Suction Cover and Side Bearings ................................................... 5-29

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Table of Contents

Compound 2-stage Screw Compressor 3225**C

viii

5.4.10.1 Disassembly .............................................................................................. 5-29

5.4.10.2 Inspection .................................................................................................. 5-30

5.4.11 Low-stage Suction Cover and Side Bearings .................................................... 5-31

5.4.1 1.1 Disassembly .............................................................................................. 5-31

5.4.11.2 Inspection .................................................................................................. 5-31

5.4.12 Thrust Bearing Block ......................................................................................... 5-32

5.4.12.1 Disassembly of the High-stage Thrust Bearing Block ............................... 5-32

5.4.12.2 Disassembly of the Low-stage Thrust Bearing Block ................................ 5-33

5.4.12.3 Inspection (High-stage and Low-stage) ..................................................... 5-33

5.4.13 High-stage Rotors and Main Rotor Casing ........................................................ 5-34

5.4.13.1 Disassembly .............................................................................................. 5-34

5.4.13.2 Inspection .................................................................................................. 5-35

5.4.14 Low-stage Rotors and Main Rotor Casing ......................................................... 5-35

5.4.15 High-stage Bearing Head and Main Bearings ................................................... 5-36

5.4.15.1 Disassembly .............................................................................................. 5-36

5.4.15.2 Inspection .................................................................................................. 5-36

5.4.16 Low-stage Bearing Head and Main Bearings .................................................... 5-37

5.4.16.1 Disassembly .............................................................................................. 5-37

5.4.16.2 Inspection .................................................................................................. 5-37

5.5 Reassembly ................................................................................................ 5-38

5.5.1 Unloader Slide Valve and Guide Block .............................................................. 5-40

5.5.2 Bearing Head and Main Bearings ...................................................................... 5-41

5.5.3 Bearing Head and Main Rotor Casing ............................................................... 5-42

5.5.4 Installing the Rotors ........................................................................................... 5-43

5.5.5 Suction Cover and Side Bearings ...................................................................... 5-44

5.5.6 Balance Piston Sleeve ....................................................................................... 5-45

5.5.7 Installing the Suction Cover ............................................................................... 5-46

5.5.8 Thrust Bearing Block ......................................................................................... 5-48

5.5.8.1 End Clearance Measurement .................................................................... 5-50

5.5.8.2 End Clearance Adjustment Procedure ...................................................... 5-51

5.5.8.3 Tightening after Finishing the End Clearance Adjustment ........................ 5-52

5.5.8.4 Installing the Balance Piston ..................................................................... 5-53

5.5.9 Balance Piston Cover and High-stage Unloader Cylinder ................................. 5-53

5.5.10 Bearing Cover .................................................................................................... 5-56

5.5.11 Shaft Seal Block ................................................................................................ 5-57

5.5.12 Low-stage Unloader Cylinder ............................................................................ 5-60

5.5.13 Unloader Cover .................................................................................................. 5-61

5.5.14 Coupling the High-stage and Low-stage Blocks ................................................ 5-62

5.5.15 Unloader Indicator ............................................................................................. 5-64

5.5.15.1 Potentiometer ............................................................................................ 5-64

5.5.15.2 Micro-switches and Micro-switch Cam ...................................................... 5-64

5.5.15.3 Reassembly ............................................................................................... 5-65

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Table of Contents

Compound 2-stage Screw Compressor 3225**C

Chapter 6 Troubleshooting

01: Compressor does not start up ............................................................................ 6-1

02: Compressor stops immediately after startup ................................................... 6-1

03: Unusually low pressure (decrease of suction pressure) ................................. 6-2

04: Low oil pressure (low lubricating oil supply pressure) ................................... 6-2

05: Intermediate pressure is unusually high ........................................................... 6-3

06: Unusually high pressure (abnormal discharge pressure) ............................... 6-4

07: Discharge temperature is abnormally high ....................................................... 6-5

08: Leak from mechanical seal ................................................................................. 6-6

09: Squeaking of mechanical seal ............................................................................ 6-7

10: Capacity control position is indicated incorrectly ........................................... 6-7

11: Capacity control malfunction.............................................................................. 6-8

12: Compressor generates abnormal vibration and/or sound .............................. 6-9

Chapter 7 Related Documents

7.1 Exploded Views, Assembly Sectional Views ............................................ 7-1

7.2 Parts Configuration Table ......................................................................... 7-27

7.3 Tightening Torques for Bolts and Nuts ................................................... 7-34

7.4 About the O-rings Used ............................................................................. 7-36

7.4.1 List of O-rings Used ........................................................................................... 7-36

7.4.2 O-ring Materials Used for Screw Compressor ................................................... 7-36

7.5 Tools for Disassembly............................................................................... 7-37

2202MYJE-MY-C8-N_2018.02.

Chapter 1 Safety

Compound 2-stage Screw Compressor 3225**C 1.1 Strict Requirements and Prohibitions

1-1

Chapter 1 Safety

1.1 Strict Requirements and Prohibitions

1.1.1 Strict Requirements (Do’s)

1.1.1.1 Do’s on Operation

 Make sure to install safety and protective devices on the package unit.  Regularly inspect the safety and protective devices if they function properly.  If the safety or protective devices do not work properly or if this product operates abnormally,

immediately stop the operation and report to the supervisor. Obtain his/her approval and direction before restarting the compressor.

 If this product stops for unknown reasons, immediately inform your supervisor of it. Obtain

his/her approval before restarting the compressor.

 Some types of refrigerants emit bad smell or toxic gases when they leak. Make sure to

ventilate the air during operation.

 For the properties of refrigerant and lubricating oil (corrosiveness, decomposability or toxicity),

be sure to obtain the Safety Data Sheet (SDS) and follow the relevant information.

 When stopping the operation of this product, close the suction and discharge side shut-off

valves and turn "OFF" the motor (main power), heater power, and control power.

1.1.1.2 Do’s on Maintenance

 Prepare work procedures based on a work schedule. Be sure to perform danger forecasting

before starting the work.

 Before performing the work together with at least one other person, thoroughly confirm each

other's work details and procedures to acknowledge the other worker's movement.

 When troubleshooting during operation or before performing setup, cleaning, maintenance,

or inspection of this product, always turn OFF the main power to the motor and control power and other devices. Also, lock and tag out them to prevent the power from being supplied erroneously during operation.

 When troubleshooting during operation or before performing setup, cleaning, maintenance,

or inspection of this product, confirm that the pressure inside this product and the package unit is at atmospheric pressure.

 Some refrigerants in use generate bad smell or toxic gases, or may cause deficiency of

oxygen. Before starting work, measure oxygen concentration in the work area as necessary. Ventilate the area well. Be sure to keep the area well ventilated until the work is finished.

 For the properties of refrigerant and lubricating oil (corrosiveness, decomposability or toxicity),

be sure to obtain the Safety Data Sheet (SDS) and follow the relevant information.

 After using tools always restore to designated place and never leave tools in the package unit

1.1.1.3 Do’s on Lockout/Tagout after Shutting Off the Power

 Attach lockout/tagout mechanism to the main breakers of motor main power and control power.

Lockout/tagout after power off is a very effective means to secure safety. It can prevent the power source from being turned on by accident by two or more workers which may cause injury to other worker(s).

2202MYJE-MY-C8-N_2018.02.

Chapter 1 Safety

Compound 2-stage Screw Compressor 3225**C 1.1 Strict Requirements and Prohibitions

1-2

 If there are any possibilities of danger during works (especially during cleaning, maintenance

and inspection, and troubleshooting), turn "OFF" the motor main power and control power, and perform lockout/tagout.

 In the following situations, workers may neglect to perform power source shutoff or

lockout/tagout. Clearly notify the workers of the necessity of lockout/tagout.

 It is assumed that workers do not perform lockout/tagout before starting work because it is

troublesome, and only turn "OFF" the main motor and control power.

 It is assumed that workers only turn off the main motor and control power and do not

lockout/tagout the main motor and control power, because they judge that there is no danger.

1.1.1.4 Do’s about Personal Protective Gear

 Prepare and use protective gear complying with the safety standards of the regulations.  Check the function of each protective gear before using.  Wear designated clothes such as work outfits, with their cuffs tightly closed.  Do not wear any neckties or jewelry as there is a risk of being entangled by a movable part or

rotating part. Put on a helmet as your hair may get entangled.

 Do not have anything in your pocket to prevent objects from falling into the machine.

1.1.1.5 Do’s about Handling of Hazardous and Toxic Substances

 Obtain the Safety Data Sheet (SDS) from manufacturers of hazardous and toxic substances.

Check the SDS and follow the handling instructions recommended by the manufacturers to handle and store those substances.

1.1.1.6 Do’s about Handling Emergency Situations

 Formulate an emergency action plan complying with the regulations, and post it on a safe

place.

1.1.1.7 Do’s about Waste Oil, Fluid, and Materials

 Disposing of refrigerant and oil used for this product are subject to a number of regulations for

the environmental protection purposes. Follow the local, state, federal acts and regulations and your company's rules when disposing of such waste oil, fluid and materials.

1.1.1.8 Other Do’s

 Clean the floor around the entire refrigerating/cold storage/gas compression package unit.

Provide a safety passage.

 Walk only on the areas set up as a work floor. Also, do not leave tools and cleaning solutions

in that area.

 If water or oil is spilled on this product or the floor, immediately wipe it off to prevent workers

from slipping and getting injured.

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Chapter 1 Safety

Compound 2-stage Screw Compressor 3225**C 1.2 Warnings

1-3

1.1.2 Prohibitions (Don’ts)

 Do not remove or relocate any safety device, including electrical interfaces.  Do not disable any safety device by short-circuiting or bypassing without any permission.  Do not leave this product unsafe and unattended, by removing a safety cover or some other

measures.

 Do not touch, clean or lubricate any part of this product which is moving.  Do not touch relays or electric systems such as terminal block with bare hands when turning

on the power.

1.2 Warnings

The warning messages described in this manual warn dangerous situations that may arise during work by using the following four categories.

Neglecting such warnings may cause accidents, resulting in personal injury or even death. Also, this product or its auxiliary equipment may be heavily damaged. Therefore, be sure to always

observe the instructions of the warnings.

Table 1-1 Warning Symbols and their Meanings

Symbol

Meaning

Indicates a hazardous situation which, if not avoided, could very likely cause serious injury or death.

Indicates a potentially hazardous situation which, if not avoided, may cause serious injury or death.

Indicates a potentially hazardous situation which, if not avoided, may cause minor or moderate injury.

Indicates a potentially hazardous situation which, if not avoided, may result in property damage.

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1-4

1.3 Residual Risks

The following information assumes that this product is operated or inspected/maintained while being used in general refrigerating/cold storage/gas compression package units.

Note that all hazardous sources cannot be predicted for the applications mentioned. Devise appropriate countermeasures for hazardous sources in your systems.

Table 1-2 Hazardous Sources

Hazardous sources

Predicted hazard

Countermeasures in

operation

Countermeasures in

cleaning, inspection,

and parts exchange

Motor and compressor coupling Refer to Figure 1-1

 Caught in due to contact

 Install coupling cover

and prohibit opening.

 Keep away.

 Turn off motor main

power and control power, and conduct lockout/tagout.

Motor terminals

 Electric shock caused by

contact with live wires or electrical leakage

 Keep away.  Do not open terminal

boxes.

 Do not touch terminal

boxes.

 Turn off motor main

power and control power, and conduct lockout/tagout.

Compressor low-stage side suction casing Refer to Figure 1-1

 Frostbite due to contact  Contact with or inhalation of

hazardous substances generated by leakage of refrigerant or the like

 Keep away and do not

touch.

 Wear protective gear.  Detect gas leakage.

 Wear protective gear.  Work under room

temperature.

Compressor intermediate piping (low-stage discharge port to high stage suction port) Refer to Figure 1-1

 Burn injury due to contact  Contact with or inhalation of

hazardous substances generated by leakage or spout of refrigerant or the like

 Keep away and do not

touch

 Wear protective gear  Gas leakage detection

 Wear protective gear  Work in temperatures

below 40 °C

Compressor high-stage side discharge casing and discharge piping

 Burn injury due to contact  Contact with or inhalation of

hazardous substances generated by leakage or spout of refrigerant or the like

 Keep away and do not

touch.

 Wear protective gear.  Detect gas leakage.

 Wear protective gear.  Work at a temperature

of not higher than 40°C.

Check valves/service valves and joints on each section of the package unit

 Contact with or inhalation of

hazardous substances generated by mishandling or leakage

 Frostbite or burn due to

contact

 Sufficient ventilation  Indicate valve

open/close state.

 Keep away and do not

touch.

 Wear protective gear.

 Sufficient ventilation  Wear protective gear.  Tagout for controlled

valve

Solenoid valves/electric valves on each section of the package unit

 Electric shock caused by

contact with live wires or electrical leakage

 Pinched due to contact with

driving part

 Install protective cover

on terminals, and prohibit opening.

 Keep away and do not

touch.

 Wear protective gear.

 Turn off each breaker

and the control power, and conduct lockout/tagout.

 Wear protective gear.

Electric components in each section of the package unit (oil heater, protective switch, etc.)

 Electric shock caused by

contact with live wires or electrical leakage

 Pinched due to contact with

driving part

 Install protective cover

on terminals, and prohibit opening.

 Keep away and do not

touch.

 Wear protective gear.

 Turn off each breaker

and the control power, and conduct lockout/tagout.

 Wear protective gear.

Package unit oil drains

 Contact with hazardous

substances generated by leakage or spout

 Burn caused by contact with

high-temperature fluid

 Sufficient ventilation  Keep away and do not

touch.

 Wear protective gear.

 Sufficient ventilation  Wear protective gear.  Work at a temperature

of not higher than 40°C.

Noises

 Damage caused by noise

 Wear protective gear.

—

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Figure 1-1 Locations of Hazardous Sources (compressor)

Photo 001 Locations of Hazardous Sources (compressor)

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1.4 Safety Devices

For safe use and protection of this product, make sure to attach safety devices to this product in accordance with the regulations and the following instructions.

Safety devices cannot be kept in normal condition unless inspected and maintained at regular intervals. Their maintenance and inspection need to be performed as an important part of the maintenance/inspection work project. Provide users of this product with necessary information on the safety devices, for example, types of the safety devices, installation position, function, and inspection method of safety related devices.

 Check the safety devices after turning on the power and before operation of this

product. If they do not operate normally, immediately take repair or replace safeties before starting this product.

1.4.1 Emergency Stop Button

 Overview/Function/Purpose

The emergency stop buttons are used to stop the compressor operation immediately if an emergency occurs in this product.

 Installation Positions

On the control board and in the operation control room

 Stop/Restoration Methods

The operating procedures for the emergency stop button, i.e., how to stop the operation and restore the normal operating condition, must be clearly defined and the information provided to the user of this product.

 Inspection Method/Cycle

The emergency stop buttons must be tested before commissioning and must also be periodically re-tested after that. The inspection procedures and the inspection interval for the emergency stop button must be clearly defined and the information provided to the user of this product.

1.4.2 Breakers of Motor Main Power and Control Power (with Lockout/Tagout Mechanism)

 Overview/Function/Purpose

Turn off the main motor and control power, and if there is any possibility of danger during work (especially during cleaning, maintenance, inspection, or troubleshooting), lockout/tagout devices must be used on the breakers of the main motor and control powers to prevent injuries to workers in case the power is turned on accidentally during work.

 Methods of Performing and Releasing Lockout/Tagout

Make sure to clearly notify methods of performing and releasing lockout/tagout referring to the regulations created by Occupational Safety & Health Administration (OSHA) or local governing body.

 Inspection Method/Cycle

The inspection procedures and the inspection interval for the lockout/tagout devices, must be clearly defined and the information provided to the user of this product.

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1.4.3 Compressor Protective Devices

 Be sure to adjust the set values and check operation of the protective devices at

the commissioning.

 Overview/Function/Purpose

These protective devices are used to protect this product.

 Protecting from discharge temperature rise (DT)

This device activates and stops the compressor operation when the compressor discharge temperature gets equal to or higher than the set value. Install a temperature sensing port to the discharge pipe.

 Protecting from oil temperature rise (OT)

This device activates and stops the compressor operation when the compressor oil temperature gets equal to or higher than the set value. Install a temperature sensing port to the oil supply pipe of the package unit (after the oil cooler).

 Protecting from high pressure (HP)

This device activates and stops the compressor operation when the compressor discharge pressure gets abnormally high due to mishandling of the compressor or suspension of water supply to the condenser. This device prevents explosion of the equipment and components. Install a pressure sensing port to the discharge pipe.

 Protecting from intermediate pressure (IP)

This device activates when the intermediate pressure of the compressor gets equal to or higher than the set value and properly controls the compressor. In some cases, this device stops the compressor operation. Install a pressure output port to the package unit's intermediate gas pipe (or compressor's intermediate gas pressure output port).

 Protecting from suction pressure drop (LP)

This device activates and stops the compressor operation when the compressor suction pressure gets equal to or lower than the set value. Install a pressure sensing port to the suction pipe.

 Protecting from oil pressure (OP)

This device activates and stops the compressor operation when the differential pressure to supply oil to the compressor (= lubrication oil supply pipe pressure − compressor discharge pressure) gets equal to or lower than the set value, due to insufficient lubricating oil, clogged filter or mixture of refrigerant into the lubrication oil. This device prevents the sliding portion from being abnormally worn or seized. Install a pressure sensing port to the package unit's oil supply pump (after the oil pump) and the discharge pipe.

 Protecting from motor over-current (OCR)

This device activates and applies appropriate control when the current gets equal to or higher than the set level flows. In some cases, this device stops the compressor operation. This device is normally installed inside the control panel.

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 Connection Positions and Settings

Specify the connection position and setting for each compressor protective device, and make sure to provide users of this product with them.

Make sure that the set values do not exceed the operating limits shown in Chapter 2, section 2.3.2 and Table 2-2 in this manual.

 Inspection Method/Cycle

Compressor protective devices require operation tests and confirmation of the settings calibration before commissioning as well as at regular intervals. Specify the inspection methods/intervals of the compressor protection devices, and make sure to provide users of this product with such information.

 In the operation test, check that alarms and protective devices operate normally

by using devices such as pressure tester. Do not operate the compressor with all the valves closed, or in any other dangerous conditions.

 If the protection from oil pressure (OP), high pressure (HP) activates, do not

restart operation until the cause of activation is removed.

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Chapter 2 Compressor Specifications and Structure

Compound 2-stage Screw Compressor 3225**C 2.1 Overview of MYCOM 3225**C

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Chapter 2 Compressor Specifications and Structure

2.1 Overview of the 3225**C

The 2-stage compression system, which has hitherto required two units of standard-type screw compressor for its embodiment, can now be realized by a single unit of compound 2-stage screw compressor.

Generally, screw compressors use oil injection to keep discharge temperature at a low level during operation without loss of volumetric efficiency even at high compression ratios. It can, therefore, be operated with a single-stage compression system even at evaporative temperatures near -40°C.

However, for normal use at low temperatures, a 2-stage compression system is applied in order to improve kW/RT (ratio of power consumption versus cooling ability). If the 2-stage compression system is configured with standard-type screw compressors, at least two screw compressor units need to be installed, one on the high-stage and the other on the low-stage, which inevitably requires double installation of the entire system including machinery, motors, utilities, etc.

This 2-stage screw compressor is produced to solve this problem. It is a single unit that has two single-stage compressor units combined into one.

The 3225**C model has a capacity control mechanism for startup load reduction on the high-stage, and a capacity control mechanism for coping with load change on the low-stage.

In addition, there are four rotor lengths for the low-stage and three rotor lengths for the high-stage. Moreover, customer is able to select each low-stage and high-stage volume ratio from two

specifications. Employing these combinations of each specification, 3225**C is providing a high versatility that can satisfy a wide range of operation conditions required by different applications at the load side. Therefore, the 3225**C models are the long-selling products which last to more than 30 years since the developed in 1982 as the large sized compound 2-stage screw compressor.

2.2 Model Designation of the Compressor

This manual describes 3225**C-*B*-51 and 3225**C-*B*-61 models. The meaning of the type designation, which is engraved on the MODEL column of the compressor

nameplate, is as follows.

*3225**C-*B*-51/61

5: Power frequency (6: 60Hz)

1: Indicates that it is a motor directly connected type. * Unless specifically specified, machines manufactured in

September, 2010 or after do not have this indication engraved on their nameplate.

Vi (volume ratio) specified for the high-stage discharge port,

standard value of which is L or M

Means a booster (low-stage machine) Vi (volume ratio) specified for the low-stage discharge port, standard

value of which is L or M

Stands for Compound (compound 2-stage machine) Specifications of high-stage rotor length, which is L, M or S Specifications of low-stage rotor length, which is LL, L, M or S High-stage rotor diameter of 250 Low-stage rotor diameter of 320 Indicates working fluid

(Example: N = Ammonia, F= Fluorocarbon, P = Propane, HE = Helium)

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2.3 Compressor Specifications

2.3.1 Standard Specifications

Table 2-1 3225**C Screw Compressor Specifications (1/2)

Items

Model

LLLC

LLMC

LLSC

LLC

LMC

LSC

Product mass

4150

4100

4020

3440

3390

3310

Low-stage swept volume @3550 min-1 /2950 min-1

m3/h

6740

/5600

6740

/5600

6740

/5600

5700

/4740

5700

/4740

5700

/4740

High-stage swept volume @3550 min-1 /2950 min-1

m3/h

2840

/2360

2380

/1980

1900

/1580

2840

/2360

2380

/1980

1900

/1580

Working fluid (Refrigerant)

Ammonia, Hydrofluorocarbon, etc.

Design pressure

MPa

2.6

Capacity control (Actual load)

10 to 100

Rotation direction

Counterclockwise viewed from motor

Connected pipe size

Low-stage suction flange

JIS 20K 350A (14”)

Low-stage discharge flange

JIS 20K 200A (8”)

High-stage suction flange

JIS 20K 200A (8”)

High-stage discharge flange

JIS 20K 150A (6”)

Journal lubrication (low-stage)

JIS 20K 40A (1-1/2”)

Journal lubrication (High-stage)

JIS 20K 25A (1”)

Oil injection lubrication

JIS 20K 20A (3/4”)

Oil return Inlet (Rotor casing)

JIS 20K 32A (1-1/4”)

Oil return outlet (Low-stage Bearing cover)

JIS 20K 32A (1-1/4”)

Oil return outlet (High-stage Suction cover)

JIS 20K 20A (3/4”)

Low-stage capacity control

Load: Rc3/8, Unload: Rc3/8

High-stage capacity control

Load: Rc3/8・Rc1/2, Unload: Rc3/8

 Unless otherwise noted, the pressure unit MPa represents the gauge pressure

in this manual.

 For limits of working temperature and pressure, see "2.3.2 Operation Limits" in

this manual.

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Table 2-2 3225**C Screw Compressor Specifications (1/2)

Items

Model

MLC

MMC

MSC

SLC

SMC

SSC

Product mass

3290

3240

3160

3150

3100

3020

Low-stage swept volume @3550 min-1 /2950 min-1

m3/h

4760

/3960

4760

/3960

4760

/3960

3820

/3170

3820

/3170

3820

/3170

High-stage swept volume @3550 min-1 /2950 min-1

m3/h

2840

/2360

2380

/1980

1900

/1580

2840

/2360

2380

/1980

1900

/1580

Refrigerant - Ammonia, Hydrofluorocarbon, etc.

Design pressure

MPa

2.6

Capacity control (Actual load)

10 to 100

Rotation direction

Counterclockwise viewed from motor

Connected pipe size

Low-stage suction flange

JIS 20K 350A (14”)

Low-stage discharge flange

JIS 20K 200A (8”)

High-stage suction flange

JIS 20K 200A (8”)

High-stage discharge flange

JIS 20K 150A (6”)

Journal lubrication (low-stage)

JIS 20K 40A (1-1/2”)

Journal lubrication (High-stage)

JIS 20K 25A (1”)

Oil injection lubrication

JIS 20K 20A (3/4”)

Oil return Inlet (Rotor casing)

JIS 20K 32A (1-1/4”)

Oil return outlet (Low-stage Bearing cover)

JIS 20K 32A (1-1/4”)

Oil return outlet (High-stage Suction cover)

JIS 20K 20A (3/4”)

Low-stage capacity control

Load: Rc3/8, Unload: Rc3/8

High-stage capacity control

Load: Rc3/8・Rc1/2, Unload: Rc3/8

 Unless otherwise noted, the pressure unit MPa represents the gauge pressure

in this manual.

 For limits of working temperature and pressure, see "2.3.2 Operation Limits" in

this manual.

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2.3.2 Operation Limits

Table 2-3 Operation Limits of 3225**C

Items

Operation Limits

Maximum discharge pressure

MPa

1.96

Minimum suction pressure

MPa

−0.080

Maximum intermediate pressure

MPa

0.588

Minimum intermediate pressure

> Suction pressure

Oil supply pressure

･ Maximum journal lubrication pressure

MPa

Discharge pressure + 0.39

･ Minimum journal lubrication pressure

MPa

Discharge pressure +0.049 and Suction pressure +0.49

･ Minimum oil injection lubrication pressure

MPa

Suction pressure +0.49

Maximum Suction temperature

°C

Minimum suction temperature

°C

−60

Maximum low-stage discharge temperature

°C

Maximum high-stage discharge temperature

°C

100

Maximum oil supply temperature

°C

Minimum oil supply temperature

°C

Maximum male rotor rotation speed

min-1

3600

Minimum male rotor rotation speed

min-1

1450

Note : Unless otherwise noted, the pressure unit MPa represents the gauge pressure in this manual.

 If operation at partial load, which is not greater than 30 % of the indicated load, is

continued for a long time except when starting up the machine, abnormal noises or vibration may be generated. So avoid such operation.

 Repeated startup and stop in a short period is harmful not for the startup devices

and electric machinery but also for the compressor itself. For information on the start/stop limitations, refer to each instruction manual. Wait at least 15 minutes after stopping the compressor before restarting it.

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2.3.3 Outer Dimensions

Figure 2-1 Outer Dimension 3225LLLC

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Figure 2-2 Outer Dimension 3225LLMC

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Figure 2-3 Outer Dimension 3225LLSC

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Chapter 2 Compressor Specifications and Structure

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Figure 2-4 Outer Dimension 3225LLC

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Chapter 2 Compressor Specifications and Structure

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Figure 2-5 Outer Dimension 3225LMC

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Chapter 2 Compressor Specifications and Structure

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Figure 2-6 Outer Dimension 3225LSC

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Chapter 2 Compressor Specifications and Structure

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Figure 2-7 Outer Dimension 3225MLC

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Figure 2-8 Outer Dimension 3225MMC

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Figure 2-9 Outer Dimension 3225MSC

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Figure 2-10 Outer Dimension 3225SLC

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Figure 2-11 Outer Dimension 3225SMC

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Figure 2-12 Outer Dimension 3225SSC

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Compound 2-stage Screw Compressor 3225**C 2.4 Structure of Compressor

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2.4 Structure of Compressor

 For names and locations of each part of the compressor, refer to Section 7.1 "Exploded Views,

Assembly Sectional Views" and Section 7.2 "Parts Configuration Table" in this manual.

2.4.1 Sectional View

Figure 2-13 3225**C Screw Compressor Sectional Views

The 3225**C model, a compound 2-stage compressor, consists of two compressors, (i) a low-stage compressor which suctions gas, working fluid, from the refrigerating unit and compresses (pressure-raises) the gas and (ii) a high-stage compressor which furthermore compresses the gas that has been pressure-raised by the low-stage compressor and sends the resulting gas to the equipment side.

In each casing (low-stage, high-stage), two screw rotors are supported on both ends by bearings. They are meshed with each other in a joint assembly. These two screw rotors are a set of a male rotor having 4 protruding lobe profiles (M rotor) and a female rotor having 6 concave lobe profiles (F rotor). They conduct compressing according to the mechanism explained below.

The standard compressor's M rotor is driven by a 2-pole motor; it operates at 3000 min-1 (50 Hz) or 3600 min-1 (60 Hz). F rotor operates at 2000 min-1 (50 Hz) or 2400 min-1 (60 Hz), conforming to the operation of M rotor.

* The actual speed of a motor is less than its calculated speed (synchronous speed). This difference is

caused by slipping of the motor rotor.

The shaft of the low-stage compressor's M rotor which is linked with the motor has a shaft seal block that keeps gas and lubricating oil from escaping from inside the compressor.

For high efficient operation, the 3225**C model has a capacity control mechanism for coping with load change on the low-stage, and a capacity control mechanism for reducing startup load on the high-stage.

Discharge port

Low-stage capacity control mechanism

High-stage capacity control mechanism

Low-stage compressor

High-stage compressor

Shaft seal block

Low-stage discharge port

High-stage suction port

Suction port

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2.5 Mechanisms

2.5.1 Basics of the Screw Compressor

The screw compressor is categorized as a positive displacement rotary compressor. As shown in Figure 2-14, the refrigerant (gas) is continuously compressed by the 3-dimensional spaces

that are formed by a pair of male and female screw rotors (with different sectional profiles) and the casing, as the spaces change continuously.

The rotor having 4 protruding lobe profiles is called a male or M rotor, and the rotor having 6 concave lobe profiles is called a female or F rotor. In this manual, they are referred to as M rotor and F rotor.

The compressor is driven by the motor connected to the shaft of the M rotor.

Figure 2-14 Compressor Mechanism

2.5.2 Suction Process

As shown in Figure 2-15, the rotors with different lobe profiles are engaged. As the rotors turn, the volume between the M and F rotor lobe profiles and the compressor casing gradually increases starting from the suction side. As the rotation continues, at a certain point when the volume reaches its maximum, the rotors isolate the gas (volume), which is enclosed by the rotors and the compressor casing, from the suction port and then continues rotation.

Figure 2-15 Suction Process

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2.5.3 Compression Process

As the rotors rotate further, the volume between the rotor lobes decreases while the sealing line moves toward the discharge side, which compresses the trapped refrigerant gas.

2.5.4 Discharge Process

The volume between the rotor lobes decreases to a level predetermined by the discharge port. With the rotations of the rotors, the compressed refrigerant gas is pushed out to the discharge port.

2.5.5 About Volume Ratio (Vi)

Volume ratios (Vi) of C-series screw compressors are indicated in performance tables or catalogs by using port symbols L and M.

The volume ratio represented by each symbol is as follows:

L=2.63, M=3.65.

Which volume ratio (L or M) should be used is decided according to operating conditions. If the compressor is used with a volume ratio that does not match operating conditions, operation will go inefficiently wasting the power.

The relationship between volume ratios and generally used compression ratios is as follows:

Figure 2-18 Volume Ratio

（Vi）

＝ πi ＝Pd/Ps κ= Cp/Cv of refrigerant gas

Vi = Design volume ratio πi = Design compression ratio

As Vi is affected by the constant of the refrigerant gas, its value that corresponds to the compression ratio will change depending on the refrigerant gas.

Figure 2-16 Compression Process

Figure 2-17 Discharge Process

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(A) Properly adapted Vi to load condition

(B) Improperly adapted Vi to load condition

Figure 2-19 Relationship between Volume ratio (Vi) and Operation Conditions

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2.5.6 Capacity Control Mechanism

The capacity control mechanism, by moving a slide valve, lets suction gas (immediately before compressed) bypass and advance to the suction side, to help shorten the rotor portion used for compression. The slide valve is located at the bottom of the casing in which the rotors mesh together, and is constructed to move parallel to the rotor shaft. This movement is changed by a cam mechanism into rotation movement. Its position (namely, capacity control ratio) is indicated externally and, at the same time, fed back to the automatic control circuit by changing the electric resistance.

Figure 2-20 Capacity Control Mechanism

2.5.7 Bearings and Balance Piston

For the load acting on the rotor perpendicular to the shaft, sleeve-type white metal-lined bearing is used. For the load acting along the shaft direction, face-to-face combination type of angular contact ball bearings is used. Special care is taken to cope with the load acting along the shaft direction. Because the M rotor is a kind of helical gear and also because the thrust force produced by discharge pressure is larger than that for F rotor, the load applied onto the M rotor is reduced by using not only a thrust bearing but also a balance piston that applies pressure from the opposing direction.

2.5.8 Shaft Seal Block

To prevent refrigerant gas and oil leakage, a mechanical seal assembly is used for the shaft seal of the M rotor.

Mechanical seal assembly is mainly composed of "rotating ring" installed on the rotor shaft and "stationary ring" installed in the seal cover. Rotating ring rotates with the shaft, and slides each other with the stationary ring while maintaining a micron class gap. The sliding each other place is called as the sliding surface.

For example, the BBSE (Balance Bellow Single Seal) which is currently used as standard seal, employs a stationary ring (mating ring) made of special cast iron, a rotating ring made from carbon, and O-rings for the packing.

Figure 2-21 Slide Valve in the

Main Rotor Casing

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2-22

2.6 Gas and Oil Flow

The compression process of the screw compressor is as described in the preceding paragraphs. Gas of the compound 2-stage screw compressor 3225**C is sent from the evaporator, and passes

through the strainer and check valve. It is drawn in from the upper central area (1) of the compressor, compressed at the low-stage side (2), and then discharged at (3).

(3) and (4) are connected with a pipe. At the mid point of the pipe, that gas is mixed with the gas from liquid cooler which was used for super-cooling.

Lubricating oil injected at the low-stage is, while kept mixed with gas, suctioned from (4) into the high-stage. After being compressed at (5), the gas mixed with lubricating oil is discharged from (6), and is sent from the oil separator to the condenser. Even if without intermediate gas cooling, oil provides cooling effect. So, the high-stage discharge temperature is maintained at a temperature not higher than 90°C.

Figure 2-22 Gas Flow

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Chapter 2 Compressor Specifications and Structure

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2-23

 Oil Supply Route

As shown in Figure 2-23, lubricating oil is split into five flows. After completing each role, the oil flows to the rotor messing part of the high-stage, and in addition to return to the low-stage rotor meshing part through the external piping. At last, both oil mixed with compressed gas and discharged from the compressor.

In standard configuration, oil injection is not performed at the high-stage.

Figure 2-23 3225**C Oil Supply Route

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Chapter 3 Installation

Compound 2-stage Screw Compressor 3225**C 3.1 General Precautions for Installation

3-1

Chapter 3 Installation

3.1 General Precautions for Installation

 This chapter (Installation) assumes that the compressor is installed to a standard refrigeration /

cold storage/gas compression package unit. If the package unit you are actually using is not the standard type refrigeration/cold storage/gas compression package unit, prepare a proper installation manual by referring to the description in this chapter and paying due consideration to safety, before installing the compressor. If there are any questions, please contact our local sales offices or service centers.

 In some cases, it may be required that installation is performed by qualified personnel. Make

sure that the work is performed by qualified personnel in compliance with local laws, ordinances and other regulations/requirements.

 Before installing the compressor, please read this chapter and related documents attentively

and fully understand their contents.

 Electrical works should be performed only by electrical engineers.

3.2 Installation Works

3.2.1 Unpacking

Confirm whether a compressor does not have abnormality including the damage.

 If there are abnormalities or deficient parts on the compressor, please contact our sales offices

or service centers immediately.

 Unnecessary packing materials should be discarded according to the laws and ordinances, or

your company's rules.

3.2.2 Storage

If you need to store the compressor before installation, perform the followings:

 Store it indoors.  Infuse nitrogen gas into the compressor and seal it. (Pressure: Approximately 0.15 Mpa )

3.2.3 Transportation

 Dropping of the lifted compressor may cause death or serious injury to the worker.

Do not stand under the lifted compressor.

1. For lifting the compressor within the safety limit, use lifting equipment and tools appropriate for the

mass of compressor.

2. Secure sufficient space for safe lifting.

3. Always check the wire ropes before using them. Thoroughly check the wire ropes for problems

such as kinks, knots and broken strands. Do not perform lifting before confirming the safety of the wire ropes. If you cannot make a correct evaluation or judgment, entrust an expert to check.

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4. To lift the compressor, attach the wire ropes to the appended eye bolts by using appropriate

shackles and hooks. Refer to Figure 3-1 and Photo 002 in next page. Use the eye bolts only for lifting the compressor. Do not use the eye bolts when lifting the compressor together with additive equipment.

 The compressor eye bolts must not be used for lifting the package unit. To lift the

package unit, use the lifting chains provided around the base or other lifting means provided on the base.

5. Check path of compressor installation to make sure it is free of obstacles in consideration of the

compressor size.

6. Before lifting, check that the hook is located above the gravity center of the compressor.

7. Direct all the workers to stay clear of the work site before lifting.

8. Before lifting the compressor, alert all workers in area of dangers during lifting process by signal

(such as calling at the beginning of the work or making a signal by hand). Do not lift the compressor unless the signals (such as calling out or hand signals) are completely understood by the workers at site.

9. Slowly reel up the wire ropes until immediately before the compressor leaves the ground.

10. Then, reel up the wire ropes a little further until the compressor is slightly up away from the ground.

Check that the compressor is not tilted. If the compressor is tilted, return the compressor to the ground and correct the tilt by adjusting the wire ropes. After that, restart the lifting operation.

11. Be sure to lift up the compressor slowly. If it is lifted rapidly, it may damage the lifting tools such as

wire ropes or a part of the compressor.

12. When the lifting work starts, observe to see if wire ropes and lifting tools are normal. Be sure that

the compressor is not tilted.

13. When moving the lifted compressor, always use guiding ropes.

14. When moving the compressor, turn away workers from the movement direction and check safety.

15. Do not lift the compressor above the safety passage unless absolutely necessary.

16. Do not lower the compressor on the safety passage. Always keep the safety passage free of

obstacles.

17. Remove any obstacles before lowering the compressor onto the ground. The compressor should

not be tilted or unstable.

18. Before lowering the compressor, announce to the workers around the working area in advance.

19. When lowering the compressor onto two or more blocks, align the tops of blocks so that the

compressor becomes stable horizontally on them.

20. Slowly lower the lifted compressor so that it is not damaged by shock.

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3-3

 Outer Dimensions, Mass and Lifting Position

3225LLLC

3225LLMC

3225LLSC

3225LLC

3225LMC

3225LSC

Product mass (kg)

4150

4100

4020

3440

3390

3310

L (mm)

2960.5

2927.5

2820.5

2863.5

2830.5

2723.5

3225MLC

3225MMC

3225MSC

322SLC

322SMC

3225SSC

Product mass (kg)

3290

3240

3160

3150

3100

3020

L (mm)

2776.5

2743.5

2636.5

2604.5

2571.5

2464.5

Figure 3-1 Outer Dimensions, Mass and Lifting Position of Compressor

Photo 002 Lifting Position

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3.2.4 Preparation for Installation

 Installation Space

Secure sufficient working space for easy operation, cleaning, maintenance, and inspection.

 Illumination

Prepare illumination devices which allow easy operation, cleaning, maintenance, and inspection.

 Ventilation

If natural ventilation is insufficient, install ventilation fans according to the relevant regulations.

 Piping

Table 3-1 List of Connecting Pipes (Compressor)

Item

Dimensions

Remarks

Suction gas inlet

JIS 20K 350A (14")

See Figure 3-2.

Low-stage gas outlet

JIS 20K 200A (8")

High-stage gas inlet

JIS 20K 200A (8")

High-stage discharge gas outlet

JIS 20K 150A (6")

Lubricating oil inlet for low-stage bearing (journal)

JIS 20K 40A (1-1/2"）

Lubricating oil inlet for High-stage bearing (journal)

JIS 20K 25A (1"）

Oil inlet for oil injection

JIS 20K 20A (3/4"）

Oil return inlet

JIS 20K 32A (1-1/4"）

Oil return outlet of low-stage

JIS 20K 32A (1-1/4"）

Oil return outlet of High-stage

JIS 20K 20A (3/4"）

Lubricating oil inlet for low-stage capacity control (Load)

Rc3/8

Lubricating oil inlet for low-stage capacity control (Unload)

Rc3/8

Lubrication oil inlet for high-stage capacity control (Load)

Rc3/8・Rc1/2

Lubrication oil inlet for high-stage capacity control (Unload)

Rc3/8

Figure 3-2 JIS20K Flange Dimensions of Compressor (mm)

D t g

N-h

20A

100 4 51

4-M12×P1.75

25A

125 5 61

4-M16×P2

32A

135 5 71

100

4-M16×P2

40A

140 5 76

105

4-M16×P2

150A

305 5 216

260

12-M22×P2.5

200A

350 5 261

305

12-M22×P2.5

350A

540 5 480

480

16-M30×P3 (Special thread)

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3.2.5 Installation

3.2.5.1 Installation

Check that the surface of the package unit, where the compressor is to be installed, is even and horizontal. If it is uneven and non-horizontal, tightening the bolts may lead to compressor deformation, which may hinder normal operation.

3.2.5.2 Shaft Alignment between the Compressor and Driving Machine

 Turn off the main power and control power of the driving machine before shaft alignment

work between the compressor and the driving machine. Be careful so that the power of instruments does not turn on during shaft alignment work. If the power turns on during shaft alignment work, the driving machine starts moving and there is a risk of being entangled with the rotating shaft.

 At the time of turning ON/OFF each electric power breaker, make sure to prevent

electric shock.

 For shaft alignment work between the compressor and driving machine, use designated

tools in normal condition. If a worn or damaged tool or a tool unsuitable for the work is used, there is a risk of being injured.

In the case shaft alignment between this product and the driving machine, be sure that the deviations within the range shown in the Table 3–2. However, if alignment tolerance of the driving machine side is more stringent than Table 3-2, please adjust to the request within the allowable value of the driving machine side.

Table 3–2 Tolerance of Misalignment

Tolerance

Offset

6/100 mm

Angularity

3/100 mm (reference: Φ100 mm)

The Figure 3–3 and 3–4 show how to measure offset and angularity when performing the centering of the shafts of the driving machine and this product using a dedicated hub, a dial gauge and a magnet stand.

Figure 3-3 Measurement of Offset Figure 3-4 Measurement of Angularity

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3-6

3.2.5.3 Piping Connection

 Refrigerant Piping

Observe the following when connecting the refrigerant piping to the compressor.

 The compressor is one of the few devices installed within the package unit that have moving

components. These moving components are adversely affected by foreign substances within the system (scale, dust, spatter, etc.). Therefore, when connecting the piping, do not allow any of such foreign substances to enter inside.

 Some compressors (mainly those for export) are charged with nitrogen gas to prevent rust. Be

sure to release the pressure before starting piping work.

 Be sure not to allow moisture to enter the piping. There is a high risk that it will cause trouble

after the start of operation. Be sure to assemble piping when it is dry.

 Cover flanges are attached to the compressor's low-stage gas outlet and high-stage gas inlet.

After installation, be sure to attach piping (intermediate piping) that links the both connection ports.

 Improper piping may cause operating problems such as oil not returning to the compressor or

liquid flow-backs.

 When connecting the piping to the compressor, use piping that is the same size as the

compressor connection port. If the pipe size of the piping is smaller than the compressor connection port, the flow of lubricating oil or refrigerant will be obstructed leading to problems.

 Do not let the mass of the piping connected to the compressor applied onto flanges or joints.

Be sure to prepare proper supports for piping.

3.2.5.4 Equipment and Devices for Protection of the Compressor

 Oil Filter

According to the requirements of the use of the package unit or the standard to apply, install an oil filter of appropriate filtration precision in the lubrication system of the compressor.

In the case of general applications such as closed-cycle refrigeration systems, we recommend to use an oil filter with beta ratio in the range of β

≥ 150 that conforms to requirements of NAS 1638

class 8 or ISO 4406 17/15/13. When the package unit requires API 619 4th/5th edition conformity, use an oil filter with beta ratio in

the range of β

≥200.

The oil filter may be clogged just after test operation. We recommend installing two oil filters in parallel. This will enable replacement of either filter during operation.

 Oil Heater for Oil Separator

To preserve the temperature of the lubricating oil before starting the compressor, install an oil heater on the oil separator. Make sure to install a protection function (e.g., with thermostat, etc.) to the oil heater to prevent overheating.

 Suction Strainer

When compatible (inter-soluble) oil is used, the mesh size of suction strainer should be not less than 200 meshes. When incompatible (non- inter-soluble) oil is used, it should be not less than 100 meshes.

For details about compatible and incompatible oils, see Section 4.1 "Lubricating Oil (Refrigerant Oil)" in this manual Chapter 4.

During the commissioning, small particles and scale may come from the system. We recommend installing a finer filter temporarily.

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 Compressor Protective Devices (Safety Devices)

To protect the compressor, install the necessary protective devices as described in Section 1.4.3 "Compressor Protective Devices" in this manual Chapter 1.

3.2.6 Airtightness Test

Perform an airtightness test on the package unit before starting commissioning. To prevent water entry in the package unit, use nitrogen gas or dry air for the airtightness test.

3.2.7 Lubricating Oil Charge

 TO select the lubricating oil to be used, refer to Section 4.1 "Lubricating Oil

(Refrigerant Oil)" in this manual.

 When refilling lubricating oil, ensure that it is clean and does not contain foreign

matters.

 Be careful that air and water are not mixed in when refilling.  To ensure that the lubricating oil does not absorb air moisture, keep it indoors in an

airtight container until use.

3.2.7.1 Initial Charge of Lubricating Oil

Depending on the package unit configuration and operating condition, specify the procedure, method and amount of the initial charge of lubricating oil, and make sure to provide users of this product with such information.

In determining the procedure and work procedure of the initial charge of lubricating oil, please care oil is to be filled in the oil filter and oil cooler always.

3.2.7.2 Additional Charge of Lubricating Oil

Specify the procedure of the additional filling of lubricating oil based on the configuration of the package unit, and make sure to provide users of this product with the information.

3.2.8 Charge of Refrigerant

Depending on the use working fluid and equipment configuration of your package unit, specify the work procedure that considered safety enough, and conduct the refrigerant initial filling work accordingly.

In addition, specify the procedure of the additional filling of refrigerant, make sure to provide users of this product with the information.

3.2.9 Check after Installation

Depending on the package unit to which this product is installed, formulate the necessary confirmation items and methods for package unit after installation and conduct them accordingly before the

commissioning. In addition, make sure to record and keep the results of your confirmation.

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Compound 2-stage Screw Compressor 3225**C 4.1 Lubricating Oil (Refrigerant Oil)

4-1

Chapter 4 Compressor and Package Unit Operation

4.1 Lubricating Oil (Refrigerant Oil)

Lubrication management is very significant to keep the compressor in a good operating condition. Take the following notes when managing lubricating oil.

4.1.1 Precautions for Selecting the Lubricating Oil

 Selection of the lubricating oil should depend on the type of the refrigerant, the type of the

evaporator used with the compressor, and the conditions under which the compressor is operated. Also to be considered when selecting lubricating oil are the properties of the oil that include not only the viscosity but also such characteristics as compatibility in refrigerant, separability from refrigerant, low temperature fluidity, high temperature thermal stability, etc.

We therefore recommend contacting our sales offices or service centers for choice of a specified brand for your system.

 Lubricating oil used for compressors must have a viscosity appropriate for lubricating the

bearings and other components in the compressors. The viscosity to be considered in this case should be the viscosity the oil shows at the oil inlet of the compressor. The viscosity of the lubricating oil significantly changes depending on the type of the refrigerant used in combination with the oil. If the refrigerant dissolves in the oil (or the oil and refrigerant are compatible), the viscosity of the oil drops to a level remarkably below the level required for operation of the compressor under some operating conditions. On the contrary, if the refrigerant does not dissolve in the oil (or the oil and refrigerant are incompatible), the viscosity may become too high when the supply oil temperature is low. For this reason, the lubricating oil must be selected such that it is supplied to the compressor with an appropriate viscosity (kinematic viscosity of 13 to 40 mm2/s) in the operating state.

 The circulation of the lubricating oil for the entire system must be considered. After lubricating

and cooling each part of the compressor, the lubricating oil is discharged with refrigerant gas. Most of the oil which is discharged from this compressor is trapped by the oil separator and is cycled to the compressor. A small quantity of refrigerant oil goes to the condenser and the evaporator. The lubricating oil is required to have sufficient fluidity and stability inside each part in the refrigerating cycle where temperatures differ.

 Note that some lubricating oils cannot be used depending on the combination with the

refrigerant. The following caution is an example case that is required especially attention.

 Be careful since polyolester synthetic oil (POE) must not be used with ammonia

refrigerant.

4.1.2 Recommended Lubricating Oils

When selecting lubricating oil, not only compatibility with refrigerant but also effects on O-rings must be considered. To prevent compressor malfunctions, we recommend the lubricating oil described below.

4.1.2.1 Recommended Lubricating oils for Ammonia Refrigerant

 Polyalkylene Glycols (PAG) Based Synthetic Oil (compatible oil)

Brand

Kinematic viscosity (40°C) mm2/s

Manufacturer

Type

JOMO Freol PN46

PAG

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 Mineral Oils (incompatible oils)

Brand

Kinematic viscosity

(40°C) mm2/s

Manufacturer

Type

SUNISO 3GS

Sun Oil

Naphthene base

SUNISO 4GS

Sun Oil

REFOIL NS 3GS

GARGOYLE ARCTIC C HEAVY

Exxon Mobil

GARGOYLE ARCTIC 300

Exxon Mobil

CAPELLA WF46

Texaco

CAPELLA WF68

Texaco

CP-1009-32

CPI

Hydrotreated paraffinic base

CP-1009-68

CPI

REFLO 46A

Petro Canada

REFLO 68A

Petro Canada

CAPELLA PREMIUM

Texaco

RHT-68

Kluber

REFLO XL

Petro Canada

 Synthetic Oils (incompatible oils)

Brand

Kinematic viscosity

(40°C) mm2/s

Manufacturer

Type

Acemire 300

Acemire

Mycold AB68

BVA

ZERICE S46

Exxon Mobil

ZERICE S68

Exxon Mobil

BERREL FREEZE 46S

Matsumura Oil Co., Ltd.

CP-4700-32

CPI

CP-4700-68

CPI

Gold-Cold 300

Golden West

GARGOYLE ARCTIC NH68

Exxon Mobil

PAO+AB REFLO SYNTHETIC 68A

Petro Canada

Gargoyle arctic SHC 224

Note

Exxon Mobil

PAO Gargoyle arctic SHC 226(E)

Note

Exxon Mobil

Note: Use only a seal of the standard BBSE type.

4.1.2.2 Oils for Systems Using Hydrofluorocarbon (HFC) Refrigerants

 Polyolester synthetic oils (POE) for R404A, R507A and R410A: compatible synthetic

oils

Brand

Kinematic viscosity

(40°C) mm2/s

Manufacturer

Type

SUNICE SL-68S

Sun Oil

POE EMKARATE RL68H

Lubrizol

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 Polyolester Synthetic Oil (POE) for R134a: compatible synthetic oil

Brand

Kinematic viscosity (40°C) mm2/s

Manufacturer

Type

JOMO Freol α100

107

POE

 When using lubricating oil of a brand not described in this section, or when using

lubricating oil along with refrigerants or gases not described in this Section, please contact us.

4.1.3 Change of Lubricating Oil Brand

When changing the lubricating oil for another brand for some reason, pay attention to the following:

 The change of lubricating oil brand may cause problems in operating conditions and

the compressor. When changing the lubricating oil brand in use, make sure to contact us because appropriate steps must be surely followed.

 Package unit composition differs depending on the characteristics of lubricating oil

(compatible/incompatible with refrigerant). As a general rule, changing compatible oil to incompatible oil or vice versa is not allowed.

 Lubricating oil contains various additives to fulfill necessary lubricating conditions. Types of

additives and their mixing ratio depend on each oil brand. We, therefore, recommend to avoid mixed use of different brands of lubricating oil. If mixed brands of lubricating oil are used, the different additives in the lubricating oil may react with each other and produce foreign substances like slurry.

 If it is necessary to change the brand of lubricating oil, collect as much as oil as possible from

the compressor as well as from the condenser, evaporator, and all other refrigerating unit components before charging the new lubricating oil. After 100 to 200 hours of operation, replace the oil again.

 When changing the lubricating oil for one of a different brand, be sure to ask the lubricating oil

supplier whether such change does not cause any problem. In particular, before changing current lubricating oil for new one by a different supplier, ask both manufacturers for any possible problems that may result from the lubricating oil change.

 There is no problem in changing the viscosity level within the same brand. However, make sure

that the viscosity grade will not cause problems during operation. (Example ： SUNISO 3GS→SUNISO 4GS)

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4-4

4.1.4 Precautions for Handling lubricating oil

 When refilling lubricating oil, ensure that it is clean and does not contain foreign matters.  Be careful that air and water are not mixed in when refilling.  To ensure that the lubricating oil does not absorb air moisture, keep it indoors in an airtight

container until use.

4.1.4.1 Precautions for Handling Polyalkylene Glycol (PAG)

PAG oil is much more hygroscopic than mineral oils and any moisture mixed in the oil may lead to rust, corrosion and wear within the package. When handling PAG oil, pay special attention to the following points.

 Do not perform oil charging in rainy weather or at a place with high humidity to prevent

absorbing moisture.

 Before charging, remove as much moisture as possible from the system by exhausting it with

a vacuum pump for a sufficient length of time and leaving the system in vacuum condition overnight.

 Do not open the lid of pail (oil container) until just before charging. Once the can is opened,

finish the oil charge as quickly as possible. (Finish the charge of a single can of oil within 15 minutes.)

 Cover any gaps between the pail opening and the charge hose so that foreign substances or

moisture cannot enter. A more effective way is to substitute any space inside the pail with nitrogen gas .

 Always charge all oil from the pail. Even if some oil remains, do not use it subsequently.  If any oil drops on a painted surface, wipe it away as soon as possible. Otherwise the paint

may come off.

4.1.4.2 Precautions for Handling Polyolester (POE) Oil

This type of oil has high hygroscopicity as polyalkylene glycol, and also exhibits hydrolyzability under high temperature environments. Moisture entry must be avoided. Therefore, special attention must be paid as with PAG when handling POE.

 Finish the charging in as short a time as possible after opening the pail to minimize exposure

to air.

 Make sure that all oil in a pail is used in a single charging. Any remaining oil must be stored

indoors with the can lid closed tightly. Do not attempt to store it for a long time.

 Because POE can hydrolyze, make sure to perform an oil analysis regularly in the package to

see if any abnormal conditions are present.

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4.1.5 Lubricating Oil Management Criteria

Lubricating oils that are managed by the criteria are classified into the following categories: (1) Synthetic oils: Polyalkylene glycols (PAG)

(2) Mineral oils: Naphthenic base oils and paraffinic base oils (3) Synthetic oils: Alkylbenzene (AB) and Polyalphaolefine (PAO) (4) Synthetic oils: Polyolesters (POE)

 Oil sampling and analysis is recommended every six months.  If the following control criteria are not satisfied, replace the oil.

◆ Note that the water content of PAG shall be excluded from the above oil replacement criteria. Refer to the Note *1 in the following table.

The analysis items and the criteria are shown in the following tables. Please note that these management criteria may be changed without notice.

Table 4-1 Synthetic Oil (PAG)

Item

Criteria

(a) Color phase

ASTM color scale: 4.0 or less

(b) Total acid number (TAN)

0.1 mg KOH/g or less

Within ±10 % from that of fresh oil

(d) Water content

2000 mass ppm or less Note1

(e) Degree of contamination

Degree of contamination measured by mass method (Millipore value) shall be 15 mg/100 mL or less

Table 4-2 Mineral Oil and Synthetic Oil (AB, PAO)

Item

Criteria

(a) Color phase

ASTM color scale: 6.0 or less

(b) Total acid number (TAN)

0.3 mg KOH/g or less

Within ±15 % from that of fresh oil

(d) Water content

100 mass ppm or less

(e) Degree of contamination

Degree of contamination measured by mass method (Millipore value) shall be 15 mg/100 mL or less

Table 4-3 Synthetic Oil (POE)

Item

Criteria

(a) Color phase

ASTM color scale: 4.0 or less

(b) Total acid number (TAN)

0.2 mg KOH/g or less

Within ±10 % from that of fresh oil

(d) Water content

200 mass ppm or less

(e) Degree of contamination

Degree of contamination measured by mass method (Millipore value) shall be 15 mg/100 mL or less

Note 1: Synthetic oils (compatible with ammonia) are so highly hygroscopic that they can absorb

moisture at the time of sampling. In addition, the ammonia content they have absorbed may be detected as the water content at the time of the analysis, making it difficult to precisely measure the water content. Thus, use the criterion value only as a reference.

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4-6

4.1.6 Lubricating Oil Replacement Timing

4.1.6.1 After Starting the Initial Operation

As the oil can easily be contaminated and degraded relatively quickly during the initial operation due to scales and deposits remaining in piping and vessels, be sure to sample and analyze the oil after 500 hours of operation.

If it is found as a result of the analysis that the criteria given in Tables 4-1 to 4-3 are not satisfied, the oil must be replaced.

4.1.6.2 During Normal Operation

Lubricating oils will degrade gradually as the system is operated over time. The rate of degradation depends on the operating condition, type of oil and amount of foreign matters

and moisture contained in the oil. The lubricating oil must be sampled and analyzed every six months. If it is found as a result of the

analysis that the control criteria given in Tables 4-1 to 4-3 are not satisfied, the oil must be replaced. If the oil filters are frequently clogged or the oil color quickly becomes darker and unclear, replace the

oil after removing the cause of the problem.

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Chapter 4 Operation of Compressor and Unit

Compound 2-stage Screw Compressor 3225**C 4.2 Precautions for Operation

4-7

4.2 Precautions for Operation

If the package unit is used in the refrigeration cycle, please keep in mind the contents of this section in particular.

4.2.1 Prevention of Liquid Flow-back Operation

Liquid flow-back is a phenomenon where refrigerant that did not completely evaporate with the gas reaches the compressor. Liquid flow-back may cause insufficient lubrication of the compressor, abnormal vibrations and noises, and abnormal foaming of lubricating oil (too much oil loss). To prevent liquid flow-back, properly adjust the expansion valve of each liquid cooler.

For details, refer to Chapter 6 "Troubleshooting" in this manual Chapter 6.

4.2.2 Purging of Non-Condensable Gases

 Some types of refrigerants emit bad smells or toxic gases. Make sure to ventilate the

air during work.

 When handling fluorocarbon refrigerants, remember that they are prohibited from

being purged into air by law.

If there is a leak on the low-pressure side of the system, air may enter the package unit. If non-condensable gas like air enters the package unit, the condensing pressure rises and the energy

consumption increases. This leads to uneconomical operation. Follow the procedure below to check for non-condensable gases.

1. When the compressor is stopped, allow the cooling water to flow to the unit's condenser for at

least 15 minutes. Check the condensing pressure by using the pressure gauge of the compressor.

2. Check the cooling water temperature.

3. Compare the condensing pressure checked in step 1 above with the refrigerant saturation

pressure that depends on the cooling water temperature (as shown in the table below).

Table 4-4 Typical Refrigerant Temperature and Saturation Pressure

■ Unless otherwise noted, the pressure unit MPa represents the gauge pressure in this manual.

4. When the pressure inside the condenser and the refrigerant saturation pressure that depends on

the cooling water temperature are approximately equivalent, non-condensable gases do not exist. When the pressure inside the condenser is 0.05 MPa or more higher than the refrigerant saturation pressure that depends on the cooling water temperature, there is a possibility of non-condensable gases entering the unit. In that case, purge the non-condensable gases from the condenser.

Temperature °C

Pressure MPa

Ammonia

R404A

R507A

R410A

R134a

0.328

0.509

0.523

0.699

0.192

0.396

0.590

0.606

0.807

0.237

0.472

0.678

0.696

0.924

0.287

0.557

0.775

0.795

1.053

0.342

0.652

0.881

0.903

1.193

0.403

0.756

0.996

1.021

1.346

0.471

0.871

1.121

1.148

1.513

0.545

0.998

1.256

1.286

1.693

0.626

1.137

1.401

1.435

1.887

0.714

1.289

1.559

1.595

2.098

0.811

1.454

1.728

1.768

2.324

0.916

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Chapter 4 Operation of Compressor and Unit

Compound 2-stage Screw Compressor 3225**C 4.3 When Stopping the Compressor for a Long Time

4-8

4.3 When Stopping the Compressor for a Long Time

When stopping the compressor for a long period of time, make sure to perform the following steps.

 Turn off the motor main power.  Turn off the oil heater power and the control power.  Close the suction stop valve and discharge stop valve.

If the operation stop period is 1 month or longer, perform the following checks.

 Operate the oil pump for 10 seconds per week.

After that, rotate the compressor shaft (10 rotations or more).

 Measure the package unit pressure once per month.  Check for refrigerant leakage once per month.

When restarting the compressor after an operation stop period of 1 year or longer, check the system for refrigerant leak and analyze the lubricating oil. If it is found as a result of the analysis that the control criteria given in this Chapter, Section 4.1.5 Tables 4-1 to 4-3 are not satisfied, the oil must be replaced.

Also check the motor insulation resistance. Supply power to the oil heater at least 1 day before operation start. Before starting the operation, confirm that the refrigerant is not condensed in the package unit by

checking the package unit temperature and pressure.

2202MYJE-MY-C8-N_2018.02.

Chapter 5 Maintenance and Inspection

Compound 2-stage Screw Compressor 3225**C 5.1 Precautions for Maintenance and Inspection

5-1

Chapter 5 Maintenance and Inspection

5.1 Precautions for Maintenance and Inspection

When reading this Section, also refer to Section 1.1 in this manual Chapter 1.

 When entering the machine room for maintenance services, ensure that sufficient

ventilation has been started and measure the oxygen concentration so that there is no risk of oxygen deficiency. The ventilation must be continued steadily until the work is completed.

 For performing the inspection work, be sure to prepare safety shoes, protective

glasses, gas mask and other proper protective equipment and do not fail to use them whenever they are required.

 After stopping the machine and before working on a regular inspection or overhaul,

be sure to shut off the main motor power, control power, and other power to each equipment and valve. After they are shut off, be sure to make the switches inoperable by others. Also, be sure to attach notification tags to prohibit operation (lock-out/tag-out).

 When any manual stop valve has been closed, be sure to make the valve

inoperable by others and put a notification tag to prohibit the operation (tag-out).

 When the compressor is to be overhauled, check that the internal pressure of this

product is at the atmospheric pressure before starting the work.

 When using lifting devices, e.g. a crane, etc. and/or lifting tools, ensure that they

can sufficiently withstand the load.

 When lifting a heavy load object, do not allow anyone’s body to put under it.  The work to turn each power supply ON/OFF or operate a lifting unit must be

exclusively performed by qualified personnel.

 When using electric tools, ensure that they are properly managed in accordance

with each instruction manual. Especially before using and while using, be sure to follow the care instructions on the safety of each instruction manual.

 Be sure to use only genuine parts for replacement. Using parts that are

not genuine can cause damage to this product or other devices during operation.

 Do not convert or modify this product or its components without prior permission

from MAYEKAWA. Otherwise, it can lead to an unexpected accident.

 Exercise sufficient care for handling a heavy load, and use such a lifting device as a

crane or work with an adequate number of personnel commensurate with the magnitude of the weight. Also, be sure to use stud bolts (safety retention bolts) and other support tools for the work. Neglecting the above warning can lead to low back pain of the worker or injury due to dropping of the parts.

 If two or more people are to work together, be sure to clearly define the work

procedures to

 share a common understanding among all workers before performing the work.  Not only the work to turn each power supply ON/OFF or operate a lifting device, but

also any type of work requiring qualification must be exclusively performed by qualified personnel.

2202MYJE-MY-C8-N_2018.02.

Chapter 5 Maintenance and Inspection

Compound 2-stage Screw Compressor 3225**C 5.1 Precautions for Maintenance and Inspection

5-2

 When checking the operation data of units and executing other daily maintenance

services, pay particular attention to avoid touching the area heated to a high temperature causing skin burns or inadvertently moving the handle of a valve leading to an erroneous operation.

 In the disassembly/inspection workplace, secure a sufficient space for temporary

storage of the removed parts and tools, replacement parts, and for the disassembling work as well as safety passages, and then put up necessary off-limit signs.

 In the workplace, secure a sufficient space and refrain from putting tools directly on

the floor or from haphazardly laying wires.

 Keep the floor clean all the time. Leaving the floor smeared with oil and the like

causes it to be slippery and may result in the fall and injury of personnel. Thus, do not leave it but wipe it off right away.

 Make sure that the temperature of the high temperature sections such as bearing

heads and discharge lines has been cooled down to normal ambient temperature, before working on them.

 When disassembling and reassembling the compressor, use the specified tools

properly. Before starting to use those tools, gain the full understanding of their characteristics and the method for use.

 During the maintenance service, keep the tools clean all the time. Using those tools

smeared with oil increases the risk of slip and fall, leading to an injury. Also during the service, there is a risk of foreign matters intruding inside the compressor to cause its damage.

 Parts are slippery with oil. Fully watch out for the risk of any object falling down.

Pay attention to any parts falling down, which could lead to personal injury.

 Before disassembly, inspections, and handling of the compressor, sufficiently

understand the disassembly and assembly procedures. This manual is not intended to provide complete disassembly and assembly procedures for the compressor. Instead, it describes only the important points in relation to the maintenance service of the compressor.

 If complete disassembly and assembly of the compressor are required, please

contact your nearest sales office or service center of MAYEKAWA.

 When removing a part, be careful not to damage it.  Place the removed parts on a clean workbench in an orderly manner.  For cleaning parts, use kerosene and/or machine parts cleaner.  Washed parts shall be dried by compressed air or wiped up using clean cloth. Do

not use synthetic textiles or woolen textiles to prevent fibers from attaching the parts.

 When separating the assembled compressor casings, sometimes it is difficult to

separate them due to the gasket stuck. In such a case, never hammer in a screw driver or flat chisel into the gap. Screw jack bolts using the screw holes to separate the casing each other. When some gap is observed between them, use a scraper to remove one side of the gasket from the surface.

 Removed bolts from each part should be classified into each used section to

prevent confusion.

2202MYJE-MY-C8-N_2018.02.

Chapter 5 Maintenance and Inspection

Compound 2-stage Screw Compressor 3225**C 5.2 Maintenance and Inspection List

5-3

5.2 Maintenance and Inspection List

5.2.1 Daily Management

For the purpose of daily maintenance, check the items listed in Table 5-1 "Daily Inspection Item" and record the results.

Regularly recording the daily operational data in an operation log makes it possible to detect any significant change in the system. This practice is particularly effective in preventing possible failures of the compressor.

It is particularly important to keep track of the records that indicate the relationship between the temperature and pressure, as it is closely related to the evaporation and condensation of the refrigerant, in quickly finding any abnormal condition of the compressor or the system.

Keeping an operation log in this way can facilitate the efforts to properly track down the cause of failure or accident that may occur in the compressor or the system, making it easier to quickly and accurately deal with the situation.

Table 5-1 Daily Inspection Items

Inspection item

Inspection details

Checkpoints and actions

Compressor

Hours of operation

hour

Total hours of operation

 Used to determine the timing of

regular maintenance and inspection

Suction pressure

MPa

Difference from the pressure that corresponds to the specified evaporation temperature

 Cleanliness of the cooling pipe

surface

 Temperature and flow of the items

to be cooled

Intermediate pressure

MPa

Difference from the normal pressure during rated operation

 If the pressure is too high (or too

low), check the conditions of the high/low-stages.

Discharge pressure

MPa

Difference from the condensation pressure for the specified cooling water temperature

 Cleanliness of the condenser

cooling pipe

 Mixing of non-condensing gas  Amount and temperature of the

cooling water

Oil supply pressure

MPa

Difference from the discharge pressure

 Whether the differential pressure is

decreasing or not

 Liquid flow-back operation  Wear of compressor parts

Pressure loss of the oil filter

MPa

Pressure difference between the inlet and outlet ports of the oil filter

 Contamination of the lubricating oil  Clogged oil filter

Suction temperature

°C

Whether upper or lower limit temperature is not exceeded

 Temperature and flow of the items

cooled

Suction degree of superheat

°C

Whether the degree of superheat is appropriate or not

 Adjustment of expansion valve  Insufficient refrigerant circulation

Intermediate temperature

°C

Whether upper or lower limit temperature is not exceeded

 Adjustment of the intermediate

expansion valve

Discharge temperature

°C

Whether it is within the upper limit temperature

 Mixing of non-condensing gas  Supply oil temperature, insufficient

amount of oil supply

 Compressor failure

Supply oil temperature

°C

Whether upper or lower limit temperature is not exceeded

 Cleanliness of the cooling pipe of

the oil cooler

Capacity control loading

Normally operation

 Damaged coil of the solenoid valve  Improper manual valve adjustment

of the solenoid assembly

Leak at the mechanical seal

mL/hr

Amount of leak per hour

 Mechanical seal failure

Noise and vibration

Abnormal noise and/or vibration

 Compressor failure

2202MYJE-MY-C8-N_2018.02.

Chapter 5 Maintenance and Inspection

Compound 2-stage Screw Compressor 3225**C 5.2 Maintenance and Inspection List

5-4

Table 5-1 Daily Inspection Item (continued)

Inspection item

Inspection details

Checkpoints and actions

Others

Motor current

Whether it is increased from the time of the commissioning

 Compressor/motor failure

Oil level of the oil separator

- Oil level height

 Oil loss  Replenish oil

Liquid level of the liquid receiver

Liquid level height

 Replenish refrigerant

Refrigerant leak check

If any leak is found

 Inside the machine room and in the

facility on the load side

■ Unless otherwise specified, the pressure unit "MPa" represents the gauge pressure in this manual.

■ Daily Maintenance Items

1. Oil level height of the lubricating oil If the oil level of the oil separator has reached the lower limit, charge the lubricating oil.

2. Oil filer element replacement When the differential pressure between the inlet and outlet ports of the oil filter exceeds 0.1 MPa, replace the filter element. During the period of initial operation, the pressure difference between the inlet and outlet ports of the oil filter can quickly become large

3. Cleaning of suction strainer Inspect the suction strainer when the operating hours of the compressor from the initial operation starting has exceeded 500 hours.

If the filter used is a temporary filter for initial operation, remove the filter. Also, as it is common that the differential pressure across the suction strainer can become large

in a short period of time, inspect and clean the suction strainer if the differential pressure is large.

4. Amount of oil leak from the mechanical seal If the amount of oil leak from the mechanical seal is considered excessive, check the amount of oil leak per hour. The table below shows the guideline on the acceptable amount of oil leak and the amount that requires inspection. If any damage is found on the mechanical seal in the inspection, be sure to replace it.

Table 5-2 Criteria of the Leakage from the Mechanical Seal

3225**C

Acceptable leakage amount (mL/hr)

≤ 6

Inspection is required (mL/hr)

≥ 18

Note: The values in the above table are only for guidance

purposes, and no guarantee is provided.

5. Contamination on the cooling water side of the condenser and oil cooler cooling pipe. The degree of contamination and clogging of the cooling pipe can significantly vary depending on the quality of the cooling water. If any gradual increase in the oil temperature and/or the discharge pressure is observed during the initial period of operation, check and clean the cooling water side of the oil cooler and the condenser regardless of the inspection schedule.

2202MYJE-MY-C8-N_2018.02.

Chapter 5 Maintenance and Inspection

Compound 2-stage Screw Compressor 3225**C 5.2 Maintenance and Inspection List

5-5

5.2.2 Periodic Inspection

Conduct inspection for the following items according to the specified intervals. In addition, observe relevant laws and regulations on the inspections and recording of the results that

are provided for other related items such as any safety devices (e.g. gas leak detectors), or other utility (gas/electricity) protection devices that constitute the cooling package unit together with the compressor.

Table 5-3 Periodic Inspection Items

Item

Inspection interval and Content

Remarks

Pressure gauge/pressure sensor

Yearly inspection

Thermometer/temperature sensor

Yearly inspection

Protection devices and safety valves

Yearly inspection

Suction strainer Inspection after 500 hours of initial operation

Perform inspection and cleaning if the differential pressure across the suction strainer is high.

Yearly inspection and cleaning

Lubricating oil Analyze the oil after 500 hours of

initial operation

Replace the oil if the analysis result does not satisfy the control criteria given in Section 4.1.5 "Lubricating oil Management Criteria".

Analyze the Oil every six months

Oil filter element

Yearly replacement

When the differential pressure between the inlet and outlet ports of the oil filter exceeds 0.1 MPa, replace the filter element.

Cooling water side of the oil cooler

Yearly inspection

Clean it if it is heavily contaminated.

Cooling water side of the condenser

Yearly inspection

Clean it if it is heavily contaminated.

Mechanical seal

Inspection every year or every 8000 hours of operation Note*

To be replaced if any abnormality is found. If it is difficult to stop equipment except for scheduled inspections, replace the part at each inspection.

Coupling

Inspection every year or every 8000 hours of operation Note*

Note*: The inspection shall be performed according to the operating period or operating hours,

whichever comes first.

2202MYJE-MY-C8-N_2018.02.

Chapter 5 Maintenance and Inspection

Compound 2-stage Screw Compressor 3225**C 5.2 Maintenance and Inspection List

5-6

5.2.3 Guidelines for the Timing of Compressor Overhaul

While the overhaul interval for the compressor depends heavily on the conditions of use, type and condition of the refrigerant and oil, the package unit, and other factors, the table below shows the recommended interval of overhaul, as a guideline.

Table 5-4 Guidelines for the Timing of Overhaul Based on the Conditions of Use

(standard package)

Category of Operating Condition

Application Example

Guideline for the overhaul

timing

Relatively stable operating condition

Cold storage and refrigeration

Every 5 years or 40,000 operating hours

Relatively variable operating condition

Ice maker/chiller

Every 4 years or 30,000 operating hours

Frequently started/stopped, and relatively changing operating conditions

Heat pump

Every 3 years or 20,000 operating hours

Note 1: The above guideline is applicable only when the package unit is used under the standard

operating conditions separately defined. (Refer to Chapter 2, Section 2.3.2 "Operation Limits" in this manual.)

Note 2: The above guideline is applicable only when the routine and regular inspection services that

are separately defined are performed. (Refer to Section 5.2.1 "Daily Maintenance" of this chapter.)

Note 3: Inspect the compressor at the intervals of specified period or operating hours, whichever

comes first.

Note 4: The above guideline is for reference only, and not a warranty period.

2202MYJE-MY-C8-N_2018.02.

Chapter 5 Maintenance and Inspection

Compound 2-stage Screw Compressor 3225**C 5.3 Compressor Disassembly Preparation

5-7

5.3 Compressor Disassembly Preparation

Although screw compressors are very reliable machines, it is still necessary to perform overhaul to inspect internal parts after a certain period of operation. This chapter 5 explains the essential points of disassembly methods, where to inspect on parts, and reassembly procedure of the compound 2-stage screw compressor 3225**C.

In principle, overhauling of the screw compressor that require complete disassembly should be performed in the maintenance factory. If you must do the overhaul work at the installation site due to unavoidable reasons, use the methods described in the following paragraphs.

However, please note that regular overhaul work requires removal of the compressor from the base frame. And then, the compressor should be placed on a work bench which has properly size area to disassembling the compressor.

When moving the compressor from the unit base to the workbench, be sure to follow the instructions given in Chapter 3, Section 3.1 "General Installation Precautions" and Section 3.2.3 "Transportation" of this manual.

Note that some parts name given in the text of this manual is followed by a number enclosed in square brackets [ ], which indicates the part identification number given in assembly sectional views or exploded views.

5.3.1 Disassembly Tools and Workplace

Prepare necessary disassembly tools for the compressor by referring to Section 7.5 "Disassembly Tools" in this manual Chapter 7.

In addition, prepare other necessary tools and materials including general hand tools, GC (green carbonite) grinding stones, sandpapers of #80 to #100, about #400 to #800 sandpapers, parts cleaner, lubricating oil, oilcan, empty can to receive drain oil, waste, etc.

If the overhaul work is to be done with the compressor removed from the installation base, prepare the work bench whose size is at least around 1.5 times the length and the width of the compressor..

In addition, a special stand for the compressor is required in order to safely perform the removal/fastening of bolts and plugs on the bottom side of the compressor. Refer to Section 5.3.5 of this chapter.

To the extent possible, choose a dry and clean workplace free from sand or dust. Note that a sufficient space is required around the compressor. In addition, it is necessary a temporary storage place for disassembled parts.

2202MYJE-MY-C8-N_2018.02.

Chapter 5 Maintenance and Inspection

Compound 2-stage Screw Compressor 3225**C 5.3 Compressor Disassembly Preparation

5-8

5.3.2 Replacement Parts

Prepare the genuine parts for replacement. Parts listed in Table 5-5, we recommend to be replaced on the occasion of each compressor overhaul. When ordering parts, be sure to inform the (a) model name, (b) serial number, (c) part name, (d) code

No. and (e) quantity required, to our sales offices or service centers. In particular, if the serial number (b) is unknown, the details of the applicable design and manufacturing

specifications cannot be identified, and thus it becomes difficult to choose correct parts. So, make sure to inform the (b) serial number to us.

Table 5-5 Replacement Parts of 3225**C Overhauling

P/N

Part Name

Code No.

Remarks

Q’ty.

6-1

Gasket, Suction Cover (1)

CS00600-320N

6-2

Gasket, Suction Cover (2)

CS00600-3225CN

12-1

Gasket, Bearing Head (1)

CS01200-320N

12-2

Gasket, Bearing Head (2)

CS01200-250N

17-1

Gasket, Bearing Cover (1)

CS01700-3225CN

17-2

Gasket, Bearing Cover (2)

CS73300-3225CN

Gasket, Balance Piston Cover

CS02300-250N

27-1

Main Bearing (1) with O-ring

CS0270-GRT

27-2

Main Bearing (2) with O-ring

CS0270-FRT

28-1

Side Bearing (1) with O-ring

CS0280-GRT

28-2

Side Bearing (2) with O-ring

CS0280-FRT

Balance Piston

CS03000-250

To be replaced if any abnormality is found.

Balance Piston Sleeve

CS03300-250

O-ring JIS B 2401 P150

PA11-150

38-1

Thrust Bearing (1)

CS03800-320

38-2

Thrust Bearing (2)

CS03800-250P

39-1

Lock Nut (1) AN21

NG31-021

To be replaced if any abnormality is found.

39-2

Lock Nut (2) AN17

NG31-017

40-1

Lock Washer (1) AW21

NG32-021

40-2

Lock Washer (2) AW17

NG32-017

O-ring JIS B 2401 G160

PA12-160

Oil Seal

CS05010-320VD

Gasket, Seal Cover

CS05200-320N

O-ring JIS B 2401 P32

PA11-032

63-1

O-ring JIS B 2401 G170

PA12-170

63-2

O-ring JIS B 2401 G190

PA12-190

65-1

O-ring JIS B 2401 P140

PA11-140

65-2

O-ring JIS B 2401 P155

PA11-155

66-1

Cap Seal (1) BE-140

CS06600-3225

66-2

Cap Seal (2) BE-155

CS06600-250

68-1

Guide Pin (1)

NE2506-016

To be replaced if any abnormality is found.

68-2

Guide Pin (2)

NE2506-012

69-1

Lock Nut (1) AN10, Unloader Piston

NG31-010

To be replaced if any abnormality is found.

69-2

Lock Nut (2) AN08, Unloader Piston

NG31-008

70-1

Lock Washer (1), Unloader Piston AW10

NG32-010

70-2

Lock Washer (2), Unloader Piston AW08

NG32-008

2202MYJE-MY-C8-N_2018.02.

Chapter 5 Maintenance and Inspection

Compound 2-stage Screw Compressor 3225**C 5.3 Compressor Disassembly Preparation

5-9

P/N

Part Name

Code No.

Remarks

Q’ty.

73-1

O-ring JIS B 2401 P44

PA11-044

73-2

O-ring JIS B 2401 G35

PA12-035

75-1

O-ring JIS B 2401 G150

PA12-150

75-2

O-ring JIS B 2401 G170

PA12-170

Ball Bearing, Indicator Cam #6000

CS07800-200

Snap ring C type External S10

NG12-010

V-ring, Indicator Cam VH10 NBR

CS08200-200B

O-ring JIS B 2401 G30

PA12-030

89-1

O-ring JIS B 2401 P24

PA11-024

89-2

O-ring JIS B 2401 P20

PA11-020

93-1

Gasket, Suction Flange (1)

CS71200-350N

JIS 20K 350A(14")

93-2

Gasket, Suction Flange (2)

CS71200-200N

JIS 20K 200A(8")

96-1

Gasket, Discharge Flange (1)

CS71200-200N

JIS 20K 200A

96-2

Gasket, Discharge Flange (2)

CS71200-150N

JIS 20K 150A

100

Mechanical Seal Assembly BBS-E

CS10002-320EBS

125-1

Set of Micro-switch (1)

CS1259-C

125-2

Micro-switch (2)

CS12500-200

129-1

Potentiometer (1) 1612 1k with Wire

CS1299-J

To be replaced if any abnormality is found.

129-2

Potentiometer (2) 200-1K with Wire

CS1299-E10

202-1

Bevel Gear 1612D ID 6 mm

CS20100-1612C6

To be replaced if any abnormality is found.

150

O-ring JIS B 2401 G220

PA12-220

Gear Coupling Assembly (Current Type)

CS1519-M

To be replaced if any abnormality is found.

159

Knurled Cup Point Socket Set Screw

NA83610-025

To be replaced if any abnormality is found.

160

Lock Nut AN15, Drive Hub

NG31-015

To be replaced if any abnormality is found.

161

Lock Washer AW15

NG32-015

165

O-ring JIS B 2401 P40

PA11-040

197

O-ring JIS B 2401 P58

PA11-058

216-1

Gasket, Lubricating Oil Inlet Flange (1)

CS71200-040N

JIS 20K 40A

216-2

Gasket, Lubricating Oil Inlet Flange (2)

CS71200-025N

JIS 20K 25A

219

Gasket, Oil Injection Inlet Flange

CS71200-020N

JIS 20K 20A

237-1

Tortional Slip Washer (1)

CS23700-320

237-2

Tortional Slip Washer (2)

CS23700-250

328

O-ring JIS B 2401 P46

PA11-046

351

Gasket, Balance Piston Lubricating Oil Outlet Flange

CS71200-020N

JIS 20K 20A

354

Gasket, Bearing Cover Lubricating Oil Outlet Flange

CS71200-032N

JIS 20K 32A

357

Gasket, Main Rotor Casing Oil Return Flange

CS71200-032N

JIS 20K 32A

421

O-ring JIS B 2401 P46

PA11-046

2(*SC)

(*MC)

431

O-ring JIS B 2401 P140

PA11-140

1 (M*C)

432-1

O-ring JIS B 2401 G165

PA12-165

432-2

O-ring JIS B 2401 G130

PA12-130

433-1

O-ring JIS B 2401 G165

PA12-165

2202MYJE-MY-C8-N_2018.02.

Chapter 5 Maintenance and Inspection

Compound 2-stage Screw Compressor 3225**C 5.3 Compressor Disassembly Preparation

5-10

P/N

Part Name

Code No.

Remarks

Q’ty.

433-2

O-ring JIS B 2401 G130

PA12-130

528

Oil Seal Sleeve with O-ring

CS52809-320VD

744

O-ring, Oil Seal Sleeve JIS B 2401 G90

PA12-090

Coupling Element

To be replaced if any abnormality is found.

O-ring Set 3225C NBR

CS7109-0M

- - Gasket Set 3225C

CS7118-0M

In case of replacing the main/side bearings of No.27 and No.28, it is not necessary to prepare the O-rings of No.432 and No.433 because the main/side bearings have the O-rings.

The sizes of O-ring No.432-2 and No.432-2 have been changed to G130 from G135 in October 2012 as a design modification.

● The part code of the O-ring is the one assigned to NBR which is standard material.

When the material of the O-ring is other than NBR, a different part code is used for

each material.

If you are using O-rings made from other than the standard material, please contact

us when placing an order.

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5.3.3 Refrigerant Gas Recovery

At the time the compressor operation is stopped, the pressure inside the compressor is still high. As such, it is necessary to lower the pressure down to the atmospheric pressure before starting the disassembly process. To do this, there are the following methods for example. Perform your recovery work in an appropriate manner considering site conditions, requirements of regulatory laws and regulations.

■ Use the bypass valve to release the high pressure gas in the package unit into the low pressure side.

■ If there is an adjacent compressor to which a permanent bypass line is connected from this compressor, operate the other compressor and lower the pressure through the bypass line.

■ Operate the refrigerating system and close the supply source valve to turn the gas into liquid, and recover the liquid at the receiver.

■ Use a refrigerant recovery machine to recover the liquid at the receiver.

In using either method, prepare a working flow sheet of the system beforehand. Check the valves to be controlled during the recovery work, according to the method to be used, by comparing them with the ones in the flow sheet, and clearly note the valves to be operated, other connected devices, and tubes on the flow sheet.

Two flow sheets must be prepared: one at the foreman and the other for posting in the workplace. In addition, prepare a work procedure document for the refrigerant recovery work to reflect the actual

conditions of the workplace, and sufficiently share the work details among all the coworkers through checking and confirmation before actually starting the work.

The gas mask and other protective gears required at each stage of refrigerant recovery work must be prepared before starting the work.

 Before the work, be sure to check and communicate the work details and procedure

among all coworkers, and carry out hazard prediction activities based on the information shared. Neglecting to do this will increase the risk of on-the-job accidents and injuries to a considerable level.

 After closing (opening) a valve for work, conduct lockout/tagout to prevent it from

being handled accidentally during the work.

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5.3.4 Removal of Connections to the Unit

 If high-pressure refrigerant gas or refrigerant-mixed lubricating oil remains inside the

compressor, refrigerant gas may blow off when the closed circuit is opened. This

may result in injury such as frostbite or loss of vision. Be sure to confirm that there is no residual pressure before opening any pipe connections.

When removing the compressor from the mounting base frame, the following parts must be disconnected beforehand:

(1) Coupling to connect the compressor to the driving machine; (2) Suction and discharge pipes of the compressor.

If the suction strainer is directly connected to the compressor, also remove the strainer;

(3) Oil supply lines to the compressor (Two journal oil inlet ports, one oil injection inlet port, and two

ports for each of the capacity increase and decrease controls);

(4) Electric wiring for capacity control operation (In some cases, the unloader indicator assembly may

be removed with the wiring left as it is. Refer to Section 5.4.1.1 in this chapter.);

(5) Compressor mounting bolts (foot bolts); and (6) Intermediate connecting piping from the low-stage discharge port to high-stage suction port of the

compressor (In some cases, this piping is not removed, and the compressor is removed with this piping attached.)

When removing oil lines from the compressor, there is possibility of gas and oil blowing out caused by residual pressure. And any residual oil in the pipe will flow out. To be prepared for this, either check the amount of oil outflow by slightly loosening the pipe joint or drain the oil from the oil temperature gauge at the supply header before removing the pipe.

Work carefully in particular when disassembling the unloader cylinder block since there is residual pressure and oil fills in the unloader cylinder. Moreover, prepare a larger volume container than the unloader cylinder volume to receive oil flowing out.

For easy reconnection, disconnected electric wires should be properly marked for identification. Any wrong reconnection may result in a startup failure or inability to operate the capacity control mechanism.

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5.3.5 Removing and Lifting the Compressor

 The work to lift up or move the compressor must be performed by a qualified operator.  Make sure that the lifting equipment and wires have sufficient load capacity for the

compressor.

 Never try to perform disassembly or assembly while the compressor is lifted in the air.

As the suction pipe is located immediately above the compressor, lift up or partially remove the pipe such that it will not interfere with the lifting device.

For the lifting positions of the compressor, refer to Photo 002 or Figure 3-1 in page 3-3 of Chapter 3 in this manual.

If the planned overhaul work includes separation between low-stage and high-stage blocks of the compressor, place the compressor on a special stand as shown in Photo 003 and then remove eight or more hexagon head cap screws around the bottom flange part. Never try to remove these bolts while the compressor is lifted in the air. Note that these bolts cannot be removed once the compressor is placed on the work bench.

Photo 003: Loosening Lower Flange Fastening Bolts

5.3.6 Draining Oil from the Compressor

Because considerable amount of oil is in the compressor, it is necessary to drain the oil beforehand.

The drain plugs are located on the bottom of the suction covers [5-1], [5-2] and on the bottom of the bearing head [11-1].

The most part of the oil will be drained from these plug holes.

The remaining oil will be drained as appropriate in the disassembly process on the surface plate work bench.

The residual oil will mainly remain inside the a) unloader cylinder, b) balance piston cover [22], c) seal cover [51], and suction covers [5-1] and [5-2].

Have oil pans and waste ready to receive oil to be drained during the disassembly process.

Photo 004: Draining Oil from the Bearing Head

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5.4 Disassembly and Inspection

During the overhaul work, be very careful in handling the parts. As the compressor is a delicate machine that is operated at very high speed, a minor handling error could result in a situation where the rotor and other major components must be entirely replaced. Another possibility is that it may cause a failure or performance degradation when the compressor is operated after the reassembly.

Please fully understand the following sections before starting the work. In general, the disassembly sequence will follow the flow shown on the left side of Figure 5-1

"Illustration of the disassembly sequence". Note that the sequence shown is an example, and it may change depending on the situation. For example, it is allowed to separate the low-stage and high-stage blocks at first, as shown on the right side of the flow.

Also, in the case of the flow on the left side, the sequence of disassembly may be reversed between the unloader cover/unloader cylinder block and the mechanical seal block.

Figure 5-1 Illustration of the Disassembly Sequence

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5.4.1 Unloader Indicator

Because the type 3225**C has a capacity control mechanism also on the high-stage, there are two unloader indicator locations. The standard operation method is such that the capacity control is used only on the low-stage during operation, and the capacity control on the high-stage is used to reduce the load during the startup phase.

As a different control method may be used depending on the system, refer to the separate electrical control schematic diagram for the plant.

Figure 5-2 Exploded View of the Standard Low-stage Indicator for 3225**C

5.4.1.1 Disassembly

■ In Case of Removing the Wiring only

When removing the wiring of the unloader indicator upon removing the compressor, it is necessary

to remove the cover as the indicator has a terminal block for the wiring. Perform the work according to the following procedure, and after removing the wires, attach the cover to them for protection.

○ Low-stage

a) Loosen the hexagon socket head cap screws [212] that are fastening the indicator glass [141]. In

this, do not loosen the Phillips screws [210] on the same surface. In this way, the assembly consisting of the parts [141], [202 to 207], [210], and [211] can be removed.

b) By removing the two each hexagon socket head cap screws [147A] and [147B] that are used to

fasten the indicator cover [146B], the cover can be removed.

c) As you can see the terminal block, remove the plastic cover on the block, and then remove the

screws to disconnect the wires.

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○ High-stage

Regarding the high-stage capacity control, the 3225*SC and 3225*LC types have the load

indication of 30 to 100% while the model 3225*LC has the load indication 0 to 100%. Accordingly, the dial [137] and micro-switch cam [127] of the types *SC and *MC are for the indication of 30 to 100% while the type *LC has the standard dial and micro-switch cam for the 0 to 100% indication, according to the standard (200UD/G) specification. Otherwise, the mechanism of the indicator is the same between all types.

a) By removing the three hexagon socket head cap screws [147] that are used to fasten the

indicator cover [146], the cover can be removed.

b) The indicator cover will be removed with the glass [141] and spacer [142] attached. While the

glass and spacer are glued, be careful not to drop these as they may be separated from the cover.

c) Remove the wiring.

Figure 5-3 Exploded View of the Standard High-stage Indicator for 3225**C

Photo 005: Removing Low-stage Indicator

Cover

Photo 006:Loosening Low-stage Micro-switch Cam Fixing Screw

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Photo 007: Removing High-Stage Indicator

Cover

Photo 008: Loosening High-stage Micro-switch Cam Fixing Screw

■ For Further Disassembly (In case of Removing as Unloader Indicator Assembly)

As the indicator is an assembly to be removed as a whole, no further disassembly should be made

unless the purpose of the disassembly is to disassemble this part.

○ High and Low-stages

a) As a result of the previous disassembly process, the micro-switch mounting plate [121], which is

mounting the potentiometer, micro-switch, and micro-switch cam, can be removed. b) Unscrew and remove the hexagon socket head cap screws [122]. c) Loosen the set screw [128] of the micro-switch cam. d) After that, the assembly can be removed by pulling it in the axial direction.

Photo 009: Loosening high-stage micro-switch

base plate fixing bolt

Photo 010: Removing the high-stage indicator

block

5.4.1.2 Inspection

The inspection procedure is described in the "Reassembly" section of this chapter, as it is often the case that the unloader indicator block is removed as an assembly and later inspected and adjusted after the overhauled compressor is reassembled and installed on the mounting base. For details, refer to Section 5.5.15 "Unloader Indicator" in this chapter.

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5.4.2 Unloader Cover

The unloader cover [74-1] [74-2] is mounted with the indicator cam [77-1] [77-2], which converts the linear motion of the unloader slide valve to a rotational motion, and their mounting parts.

The indicator cam is supported by the ball bearing [78] and fixed to the cover with a bearing gland [80]. To make it airtight, the V-ring [82], spring [83], and spring retainer [84] are also attached. The indicator cam has a spiral groove of 340° to cover the moving range of the unloader slide valve.

The indicator cam shaft is rotated being pushed by the guide pin [68-1] [68-2] on the top end of the unloader push rod [67-1] [67-2].

Figure 5-4 Unloader Cover Block

5.4.2.1 Disassembly

a) Unscrew and remove the unloader cover mounting hexagon socket head cap screws [76-1] and

[76-2].

b) Pull the cover out in the direction parallel to the axis of the push rod in the unloader cylinder.

Carefully pull it straight, because if the unloader cover is pulled sideways, the shaft of the indicator cam may be bent.

c) If the indicator cam will not move normally, check the spiral groove of the indicator cam, bearing,

and guide pin. The disassembly sequence is as follows:

c-1) As the bearing gland [80], which fixes the indicator cam in place, is secured by three

hexagon socket head cap screws [81] on the cylinder side of the unloader cover, unscrew and remove these bolts.

c-2) Then, the indicator cam can be pulled out with the ball bearing [78] and the snap ring

(retaining ring) [79] attached to the shaft.

c-3) Inside the unloader cover, the spring retainer [84], spring [83], and then V-ring [82] are

assembled in this order. Because the V-ring is tightly engaged with the bore of the unloader cover, the lip of the V-ring will be damaged when it is once removed, making it unusable again. Therefore, be sure to replace it with a new one once it is disassembled.

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Photo 011: Removing the Unloader Cover

Photo 012: Ball Bearing for the Indicator Cam

Photo 013: Indicator Cam Mounting Parts

Photo 014: V-ring (Black part is NBR/FKM)

5.4.2.2 Inspection

a) Check the packing portion of the indicator cam shaft for any flaw. If the refrigerant leaks without any

flaw observed in this part, it should be due to a defect of the V-ring or installing the V-ring without sufficient oil.

In this case, replace the V-ring.

b) Check the spiral groove of the indicator cam. If an abnormal flaw or wear is observed, replace it with

a new one.

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5.4.3 Unloader Piston and Unloader Cylinder

Inside the unloader cylinder [60-1] [60-2] is an unloader piston [64-1] [64-2] around which the cap seal [66-1] [66-2] and O-ring [65-1] [65-2] are fitted. The unloader piston is assembled to the unloader push rod [67-1] [67-2], which operates the unloader slide valve, with the lock nut [69-1] [69-2].

Figure 5-5 Unloader Cylinder Block

(Low-stage)

Figure 5-6 Unloader Cylinder Block

(High-stage)

5.4.3.1 Disassembly

a) Screw two M8 eyebolts into the threaded holes of the unloader piston [64-1] [64-2], and pull it fully

towards you.

b) Unbend the locking tooth of the lock washer [70-1] [70-2], which is used to fix the piston on the push

rod, such that the lock nut [69-1] [69-2] can be turned. Then, loosen and remove the lock nut.

c) Now, you can remove the unloader piston.

Photo 015: Release the Locking Tooth of the Lock Washer (High-stage)

Photo 016: Use Lock Nut Wrench to Loosen the Lock Nut (High-stage)

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b) The low-stage unloader cylinder [60-1] is

fastened by eight long hexagon socket head cap screws [62-1] to the low-stage bearing head [11-1] together with the bearing cover [16]. Even when all the hexagon socket head cap screws are removed, the unloader cylinder will not drop off as it is securely engaged with the bearing cover. Pull out the unloader cylinder by holding the flange or rib.

c) The high-stage unloader cylinder [60-2] is also

fastened by hexagon socket head cap screws [61] (× 2) and [62-2] (× 6). The high-stage unloader cylinder is to be pulled out similarly to Step b) for the case of low-stage cylinder. However, if the cylinder is to be further disassembled, leave the two bolts [61] fastened. Remove the bolts [24] and [62-2] fastening the balance piston cover [22] and remove the unloader cylinder together with the balance piston cover. In this, as oil remains in the balance piston and side bearing part, be careful of the oil that will come out when the balance piston cover is removed. If the gasket [23] is sticking and it does not come off, screw in two M8 eye bolts to the two forcing screw threads on the balance piston cover to separate the gasket.

5.4.3.2 Inspection

a) Both the O-ring [65-1] [65-2] and cap seal

[64-1] [64-2] that are on the periphery of the unloader piston [64-1] [64-2] must be replaced by new ones.

b) As it is often seen that the inside of the

unloader cylinder has flaws or is contaminated by oil residue, thoroughly clean the area and use fine sandpapers to finish the surface.

Photo 017: Removing the Low-stage Unloader

Cylinder

Photo 018: Removing the Balance Piston

Cover and Unloader Cylinder together

Photo 019: Removing the Cap Seal

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5.4.4 Shaft Seal Block

Photo 020: Seal assembly

No.

Part Name

101

100

Mating ring

Stationary rings

102

Insert lock pin

103

O-ring

109

Seal collar

Rotating rings

111

Seal collar set screw

112

O-ring

528

Oil seal sleeve

529

Set screw for oil seal sleeve

744

O-ring

Retainer, oil seal

O-ring

Oil seal

Spring pin

Figure 5-7 Exploded View of BBSE-type Mechanical Seal Assembly and Rerated Parts

5.4.4.1 Disassembly

a) Of the eight hexagon socket head cap screws [53] securing the seal cover [51], remove six bolts

leaving two diagonally opposite bolts.

b) Loosen the remaining two screws alternately and evenly, a little at a time. When the screws are

loosened to some extent, the seal cover will be pushed by the spring force of the seal to create a gap under the cover. The gap will not be created if the gasket is sticking to both surfaces. In this case, free the cover by screwing M8 eye bolts into the jacking screw threads on the seal cover to separate it.

c) As the oil inside will flow out through the gap, be ready to receive the oil with a container. d) Pull out the seal cover in the direction of the rotor shaft axis. Inside the cover, there is the mating

ring fitted with the O-ring. In this, carefully remove the seal cover for the mating ring not to be damaged by touching the shaft.

e) Remove the O-ring [49] between the seal cover and oil seal retainer [48].

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f) After the seal cover has been removed, wipe clean the shaft and then check its surface. If any flaw

is found, use a fine sandpaper to smoothen the surface. This correction is intended to prevent possible damage of the internal O-ring when the mechanical seal is pulled out.

g) Loosen the set screws [111] securing the seal collar [109] about three turns. Do not remove the set

screws completely. Loosen them such that their ends are retracted from the surface of the seal collar. These two screws are located 90° apart from each other.

h) Pull out the mechanical seal assembly by holding the seal collar with your fingertips. While

removing the assembly, make sure that the ends of the set screws do not touch the shaft surface. Any scratch on the shaft will cause leakage.

i) Pull out the oil seal sleeve [528] after removing the two set screws [529] . j) Screw two M8 eye bolts into the screw holes in the seal retainer and pull out the seal retainer while

keeping it in the right angle with the shaft.

k) Remove the oil seal [50] that is atacched into the oil seal retainer.

Photo 021: Removing the Seal Cover

Photo 022: After Removal of the Seal Assembly

5.4.4.2 Inspection

a) Although it is instructed that the mechanical seal must be replaced after abnormality is found in the

inspection, only visually checking the sliding surface may be insufficient in determining any abnormality. It is thus recommended to always replace it with a new one, similarly to the case of O-rings and gaskets, if the inspection is done in such a way.

Also, if it is difficult to stop the compressor operation except for scheduled inspections, we

recommend to replace the mechanical seal assembly with a new one at every inspection of this block. However, even if the assembly is to be replaced without exception, it is still necessary to visually check the condition of the sliding surface between the mating ring and the seal collar. If any unevenness or flaw is observed on the sliding surface, analyze the condition to determine whether it is due to aging, overheating, or other reasons in order to take necessary corrective actions.

b) Replace the O-rings every time the mechanical seal assembly is inspected because they normally

swell and deform over time.

c) Check the wear of the oil seal sleeve in the area it rubs against the oil seal lip.

If wear is evident, replace both the oil seal [50] and oil seal sleeve [528] with new parts. Since the oil seal is made of a special material, only genuine oil seals must be used for the replacement.

Information on the O-ring [744] for the oil seal sleeve A design modification was made in March 2010 to insert an O-ring [744] in the oil seal sleeve.

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5.4.5 Bearing Cover

The bearing cover [16] should be removed when the low-stage thrust bearing block is inspected or the rotor is pulled out for inspection.

5.4.5.1 Disassembly

a) Unscrew and remove all the hexagon socket head cap screws [18-1]. The bearing cover remains

attached to the bearing head [11-1] with two alignment pins [19-1].

b) For safety, screw two stud bolts into appropriate top bolt holes. c) There are two jacking screw holes in the opposite positions. By screwing in two left and right M8 eye

bolts evenly, the bearing cover will be separated from the bearing head. When some gap is observed between them, use a scraper to remove one side of the gasket [17-1] from the body.

d) Further screwing in the eye bolts will disengage the bearing cover from the alignment pins.

 At this point, if the bearing cover is not properly supported, it may fall or drop down

onto the rotor shaft to cause damage on it. So, be sure to protect the shaft with a blanket or other protective covering before starting the work.

Photo 023: Removing the Bearing Cover

Photo 024: Removing the Bearing Cover

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5.4.6 Separating High-stage and Low-stage Blocks

The high-stage and low-stage blocks should be separated before inspecting the gear coupling, high-stage thrust bearing, main bearing, pulled out rotors, etc.

As explained at the beginning of Section 5.4 of this chapter, the separation may be done at the initial step of the overhaul work.

5.4.6.1 Disassembly

a) As it is explained in the Section 5.3.5, the bolts on the bottom side must be removed by

placing the compressor on a special stand before starting the disassembly work.

b) Remove the hexagon socket head cap screws [18-2] that fasten the high-stage bearing head [11-2]

to the low-stage suction cover [5-1].

c) As the gasket [17-2] is sticking to both surfaces of the high-stage bearing head and the low-stage

suction cover, use the bolts [18-2] that have been removed to screw them into the jacking threads in the bearing head to evenly push the suction cover to separate the two blocks.

d) The gear coupling assembly [151 to 161] for power transmission is located inside, on the side of the

M rotor shaft. As the drive side and driven side of the coupling can be separated along the shaft axis, move the main body exactly along the shaft axis to separate them.

Photo 025: Screwing in the Bolts to Push and

Separate

Photo 026: Separating the High-stage and

Low-stage Blocks

5.4.7 Gear Coupling

The gear coupling, which is used as a power transmission means, is divided into the high-stage and the low-stage blocks, with each block attached to the corresponding M rotor shaft, and these two blocks are directly connected by a drive sleeve.

5.4.7.1 Disassembly

a) The drive sleeve [151] can be removed by hand after the high-stage and low-stage are separated. b) On the high-stage (driven) side, first loosen the knurled cup point socket set screw [159] on the

driven hub used for locking, and then pull out the driven hub. The driven hub can be easily pulled out, as clearance fit is used.

c) To remove the low-stage drive hub [152], release the locking teeth of the lock washer [161] and

loosen the lock nut [160].

d) There are two screw holes in the drive hub.

Screw M8 eye bolts into these screw holes and pull out the drive hub. It can be easily pulled out, as clearance fit is used.

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5.4.7.2 Inspection

Check the hub and sleeve for possible deformation of the gear teeth and wear on each tooth flank. If it is found abnormal, replace the whole gear coupling assembly. At the same time, investigate the

cause of the abnormality.

Photo 027: Current Gear coupling parts

Photo 028: Low-stage Gear Coupling

Gear coupling mechanism of 3225**C models

The gear coupling of 3225**C uses a coupling hub and drive sleeve. While the old couplings (before the design modification made in February 2011) have a stop on both outer ends of the sleeve to prevent the sleeve from dropping off, the stops are placed on the inside of the drive sleeve after the design modification (compatible with the old type).

After this design modification, the drive sleeve stopper [154] and stop ring [155] are no more used.

The gear coupling assembly consists of the items

151, 152, 153, 154*2, 155*4, and 159.

The gear coupling assembly consists of the

items151, 152, 153, and 159.

Figure 5-8 Conventional Method (Before the

Design modification in Feb. 2011)

Figure 5-9 New Method (After the Design

modification in Feb. 2011)

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5.4.8 Removing Oil Injection Pipe

The oil injection pipe [85] is located at the bottom of the low-stage suction cover [5-1].

5.4.8.1 Disassembly

Remove the oil injection pipe gland [164], and then hold a M20 bolt screwed into the screw hole on the head of the oil injection pipe to pull out the pipe.

Photo 029 Removing Oil Injection Pipe

Photo 030 Removing Oil Injection Pipe

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5.4.9 Balance Piston

During the operation of a screw compressor, both the rotation rate and the thrust load of the M rotor are higher than those of the F rotor. Accordingly, the service life of the thrust bearing for the M rotor will be significantly shorter than that of the F rotor, if no special measures are taken. As such, in order to reduce the thrust bearing load on the M rotor side, a hydraulic piston is used on the shaft end of the rotor drive shaft to cancel the thrust load.

◆ Note that no balance piston is used on the low-stage. Because the low-stage pressure condition is lower than high-stage, the service life difference of the bearings is not so significant compared to the high-stage.

5.4.9.1 Disassembly

a) Remove the snap ring [32] retaining the

balance piston [30] on the shaft using external snap ring pliers.

b) Pull the balance piston straight out by

screwing two eye bolts into the screw holes. While the rotor shaft has a balance piston key [31], it is unnecessary to remove the key.

c) To prevent rotation of the balance piston sleeve [33], there are

hexagon socket head set screws [34] screwed from both the M rotor side (balance piston) and F rotor side. So, loosen the set screw on the F rotor side, and place the M rotor side screw under the suction cover as shown in Photo 032.

d) Remove the snap ring [37] securing the balance piston sleeve using

the internal snap ring pliers. As the snap ring is pressed out by the internal O-ring [35], slightly pushing it can easily remove the snap ring.

e) Remove the balance piston sleeve and O-ring.

As clearance fit is used to engage the outside of the sleeve with the suction cover, you can easily pull it out. As there is an O-ring spacer [36], also remove the spacer.

5.4.9.2 Inspection

While you will be able to find some trace of wear on the inside surface of the balance piston sleeve, such wear is not abnormal as it is caused because the clearance between the balance piston and the sleeve is narrower than the clearance between the rotor shaft and the bearing.

Because enough clearance is given to the outside of balance piston sleeve in order not to apply the bearing load to the balance piston, no further development of the wear is expected.

However, you should still carefully check the condition because when the side bearing is significantly worn, the balance piston may also be worn.

Figure 5-10 Balance Piston Block

Photo 031

Photo 032

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5.4.10 High-stage Suction Cover and Side Bearings

If the work sequence is such that the thrust bearing block is disassembled first and then the suction cover is removed, there is a risk that, when the suction cover is separated from the main rotor casing, the rotor may also be pull out and dropped. As such, in the procedure described in this manual, the suction cover is removed first, and then the thrust bearing is disassembled.

 In this procedure to remove the suction cover before disassembling the thrust bearing

block, it is necessary to sufficiently loosen the lock nut that are securing the thrust bearing while the rotor is supported by both the main and side bearings, in order not to damage the rotor during the disassembly process.

5.4.10.1 Disassembly

a) Remove the hexagon head bolts [45-2] and the conical spring washers [46-2] that are used to fasten

the thrust bearing gland [43-2], and then remove the gland.

In case of a former model which uses a rotation stopper fitting instead of a conical spring washer,

extend the bent plate of the rotation stopper and remove it from the hexagon head blot [46-2], and then remove the hexagon head bolt and the thrust bearing gland.

Photo 033 Removal of Hexagon Head Bolts

Photo 034 Loosening the Lock Nut

b) Unbend the rotation stopper tooth of the lock washer [40-2] holding the lock nut [39-2] which retains

the inner race of thrust bearing [38-2] on the rotor shaft and loosen the lock nut using a lock nut wrench.

c) As the height of the high-stage main rotor casing is low, the casing is installed like a bridge to

connect between the suction cover and the bearing head. As such, the main rotor casing will be supported only by one side (i.e., overhang) when the suction cover is removed. To avoid this, either place squared timbers or use a lifting device to properly support the main rotor casing.

d) Loosen and remove the hexagon socket head cap screws [2-2] securing the high-stage suction

cover [5-2] to the high-stage main rotor casing [1-2].

e) As the gasket [6-2] of the suction cover is sticking to the surface of the flange, screw two hexagon

socket head cap screws [2-2] that have been removed into the screw holes in the main rotor casing flange to evenly push the suction cover. When some gap is observed between them, use a scraper to remove one side of the gasket from the surface.

f) When it comes to the position the alignment pins are disengaged, pull out the suction cover at once

along the rotor axis.

g) As the high-stage suction cover is installed with an O-ring [328] and O-ring gland [326-2] in the

opening for the push rod to pass through, remove them. As the four bolts fastening the O-ring gland are small (M5), be careful not to lose them.

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h) The side bearing [28-2] has been press fit from the balance piston cover side of the suction cover.

Remove the snap ring [29-2] using internal snap ring pliers.

i) Either push out the side bearing from the main rotor casing side using some block or pull it out using

a special tool such as shown in Photo 034. For the details of the special tool, refer to Section 5.5.2 in this chapter.

Photo 033 Pulling Out the Suction Cover

Photo 034 Removing the Side Bearing

5.4.10.2 Inspection

a) Check the oil inlet path to the balance piston part of the suction cover by spraying air or the like.

b) We recommend unconditional exchange of the side bearings on the occasion of the compressor

overhaul, but for confirmation of the compressor condition and system operating condition, carefully check the sliding part metal surface of the side bearings.

If the metal surface is turned gray or any foreign matter is embedded, also carefully check the wear

of the rotor shaft.

c) The inside surface of the main rotor casing should have no problems because sufficient clearance is

provided. However, if any trace of scraping by the end of the rotor is found, it should be determined that the thrust bearing is defective. It is also necessary to check the operational condition, such as whether the system is operated for a long time with a high intermediate pressure.

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5.4.11 Low-stage Suction Cover and Side Bearings

Similarly to the case of the high-stage, the lock nut fastening the thrust bearing should be loosened before removing the suction cover.

5.4.11.1 Disassembly

a) Remove the hexagon head bolts [45-1] fastening the thrust bearing gland [43-1] and O-ring [150].

As conical spring washers [46-1] are used together, be careful not to lose them.

b) Unbend the tooth of the lock washer [40-1], and loosen the lock nut [39-1]. c) Loosen and remove the hexagon socket head cap screws [2-1] securing the suction cover [5-1] to

the main rotor casing [1-1].

d) Drive in the alignment pins [3-1] to the main rotor casing side as shown in Photo 35. If it is not

feasible, screw in suitable bolts to the jacking screw holes on the flange to push the suction cover evenly.

e) At this time, the alignment pins will also be disengaged. Even after the alignment pins are

disengaged, as the rotor shaft and side bearing are still engaged together, pull out the suction cover carefully along the shaft axis (Photo 36).

f) Remove the snap ring [29-1] holding the side bearing using internal snap ring pliers. g) Either push out the side bearing from the main rotor casing side using some block or pull it out using

a special tool such as shown in Photo 037. For the details of the special tool, refer to Section 5.5.2 in this chapter.

Photo 035

Photo 036

Photo 037

5.4.11.2 Inspection

Inspect the suction cover and side bearings in the same way as for the high-stage.

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5.4.12 Thrust Bearing Block

5.4.12.1 Disassembly of High-stage Thrust Bearing Block

Table 5-6 Component Parts of the High-stage Thrust Bearing Block

P/N

Name

Q'ty

38-2

Thrust bearing (2)

39-2

Lock nut (2)

40-2

Lock washer (2)

42-2

Thrust bearing alignment spacer (2)

43-2

Thrust bearing gland (2)

45-2

Hexagon head bolt

46-2

Conical spring washer (2)

237-2

Torsional slip washer (2)

250-2

Thrust washer (2)

The high-stage thrust bearing block of 3225**C has no spacer for the thrust bearing outer race. While the thrust bearing outer race spacer is used to support (i.e., ensure a sufficient support width for) the outer race of the thrust bearing, 250 or higher models use no spacer for the thrust bearing outer race because the case (bearing head) side has sufficient margin to the support it.

a) Remove the lock nut [39-2] that has been loosened. Then, remove the torsional slip washer [237-2],

lock washer [40-2], and thrust washer [250-2].

b) The clearance fit is applied to two gaps between the outer race of the thrust bearing and the bearing

head, between the inner race of the thrust bearing and the rotor shaft. Prepare a 1 or 2 mm diameter aluminum wire, make the tip of the wire flat by hammering, and

slightly bend the tip to make a hook. Then, insert the tip of the wire between the outer race and the ball retainer of the thrust bearing [38-2] to hook and pull out the bearing. In this way, the bearing can be easily removed.

c) The whole thrust bearing will be removed helped by the surface tension of the oil on the side face.

If you have failed to remove the whole bearing at once, put the components in the order of the removal.

d) Inside the thrust bearing is an alignment spacer [42-2] for the inner race on the rotor shaft side. The

M rotor side has a marking of "M", and the F rotor side has a marking of "F".

Neatly arrange the parts removed, i.e., the thrust bearing gland, thrust washer, thrust bearing, and thrust bearing alignment spacer, separately for the M rotor and F rotor as shown in Photo 040. You must be very careful because if an assembly error is made to result in a wrong combination of parts after failing to neatly arranging and separating the parts, it can lead to performance degradation and/or dragging accident due to overheating caused by being too narrow clearance, for example.

Photo 040

Figure 5-11 High-stage Thrust Bearing Block

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5.4.12.2 Disassembly of Low-stage Thrust Bearing Block

Figure 5-12 Low-stage Thrust Bearing Block

Photo 041

Unlike the high-stage, the low-stage thrust bearing block of 3225**C is using an oil supply spacer for the combined surface. This is to facilitate lubrication of the ball bearing because as the rotor diameter becomes larger, the rotor shaft diameter become larger. Thus, a larger thrust bearing is required and the ball rotation speed increases accordingly. Furthermore, as with the high-stage, the low-stage thrust bearing block of 3225**C has no spacer for the thrust bearing outer race.

a) Remove the lock nut [39-1] that has been loosened. Then, remove the torsional slip washer [237-1],

lock washer [40-1], and thrust washer [250-1].

b) Similarly to the case of the high-stage, remove the thrust bearing [38-1] and the thrust bearing

alignment spacer [42-1].

5.4.12.3 Inspection (High-stage and Low-stage)

a) The thrust bearing is normal if the bearing balls are found fully glossy after the thrust bearing has

been fully washed and cleaned. It is abnormal if the ball surface has tarnish streaky pattern.

b) Support the inner race with your hand and rotate the outer race. If you feel abnormal vibration on the

hand, the rolling contact surface of the inner or outer race or some balls may be in an abnormal condition. So, carefully check the conditions. You could feel some irregular click even with a small foreign matter that has entered during the removal process. In such a case, it should return to the normal condition when high pressure air is used to blow out the foreign matters after washing and cleaning the unit. If the bearing is determined to be defective, it must be replaced with new ones.

c) If the inner race and outer race can be easily separated, the wear is considered excessive. If so, you

cannot reuse the bearing.

d) After washing the bearing, you should be able to hear a clattering sound when the bearing is rotated

by hand. Such a sound is due to the motion of the ball within the backlash or play, or the gap between the retainer and the ball. Such a sound will not be heard if the bearing is held horizontal and turned. If some lubricating oil is applied after washing the bearing, the sound should not be heard when the bearing is turned. If you can still hear the sound, the bearing is abnormal.

e) If any abnormality is seen in the thrust bearing in the above inspection, replace with new ones.

In addition, carefully check the reason whether due to mere aging or any problem with the operating condition and/or lubricating mechanism.

f the compressor has been operated for more than 20,000 hours without replacing the thrust bearing,

it is recommended to replace the bearing with a new one for safely continuing the operation until the next overhaul, even if no abnormality is found in the above described inspection.

 As the bearing used for the compressor is a specially designed combined-type bearing, the

accuracy and material are different from normal ones of the same part number that may be found in the catalogue of a bearing manufacturer. Be sure to use only genuine parts for replacement. Otherwise, it will not be covered by the warranty.

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5.4.13 High-stage Rotors and Main Rotor Casing

5.4.13.1 Disassembly

a) While you can pull out the rotor either from the M or F side, you should be very careful in the work as

either rotor is very heavy.

When pulling out the M rotor (or F rotor) first, pull out about 2/3 of the full length of the rotor by

holding the shaft upward and turning it in the CW (or CCW) direction.

 You should carefully note that the rotor must be rotated in the specified direction

while pulling it out. If the M (F) rotor is not turned during the pulling out process, the F (M) rotor can also be pulled out together.

b) As a preparation, use a nylon belt or other lifting belt that will not blemish the lifting surface to

support the center of the rotor. Then, pull out the rotor while slightly lifting up the rotor using the belt.

Photo 042 Pulling Out the F Rotor

Photo 043 Lifting Up the F Rotor

Photo 044 Pulling Out the M Rotor

Photo 045 Lifting Up the M Rotor

c) The pulled out rotor should not be directly

placed on the floor. Use appropriate wood boards to support the rotor as a cushion to prevent blemishing or use V-blocks to support the shaft to prevent blemishing of the outer surface (See Photos 046 and 048.)

Photo 046

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5.4.13.2 Inspection

a) No abnormality should be observed on the surface of the rotor lobes under normal operations.

Regarding the contact surface of the teeth, black luster should be seen on the root area of the M rotor lobes and on the tip area of the F rotor lobes.

In other cases, when the suction gas or oil is contaminated by fine dust, there may be fine linear scratches on the shaft surface, in the direction perpendicular to the shaft axis. If any such flaw is found, use a fine sandpaper or grindstone to smooth the surface.

b) In case of ammonia refrigerant or gas compressor, the non-contact surface of the rotor may be

discolored by rust or deposits. Use sandpapers or others to finish the surface according to the degree of the problem.

c) Then, check the bearing areas of the rotor shaft. Two types of finishing are used: one is the

induction hardening (polish finishing) for the standard specification, and the other is the hard chrome plating (polish finishing), as a special specification. The most suitable finish is selected according to the type of refrigerant and operation conditions.

Very little wear will be present unless the compressor is operated for a long time using dirty oil or any hard matter is buried in the metal of the inner circumference of the bearing.

d) Check the portion of the shaft on which the thrust bearing is mounted for any trace to show that the

inner race of the bearing has rotated. If the lock nut that fastens the inner race of the thrust bearing is loosened, or if the bearing is abnormally worn, the inner race will become rotate. If any trace of rotation is seen, correct the problem. Depending on the degree of the rotation trace, it might be necessary to replace the rotors with new ones.

e) Check the inner surface of the main rotor casing.

There is a narrow clearance between the periphery of the rotor and the main rotor casing. Any slight flaw present on the tip of the rotor teeth or on the inner surface of the main rotor casing, due to small foreign matters, will not be a problem. If there is any trace to show that the tips of the rotor teeth have hit the inner surface of the main rotor casing, it is an abnormal condition. In such a case, the possible cause is that the main bearing and/or side bearing is worn out. Take proper actions by finding the cause of the problem, such as contamination of the lubricating oil or entrance of foreign matters.

5.4.14 Low-stage Rotors and Main Rotor Casing

Perform the work similarly to the case of the high-stage unit. The work should be very carefully performed as the low-stage rotors are heavier than the high-stage rotors.

Also perform the inspection work similarly to the case of the high-stage unit. As the low-stage M rotor is installed with a mechanical seal, do the work very carefully not to damage

the shaft. It is recommended to apply a protective tape on the shaft surface.

Photo 047 Pulling Out the Low-stage M Rotor

Photo 048

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5.4.15 High-stage Bearing Head and Main Bearings

On the rotor mounting side of the bearing head [11-2], there is a gas discharge port as determined by the operating conditions of the compressor. This discharge port affects the performance of the compressor. In addition, the bearing head has the main bearing that supports one end of the rotor.

5.4.15.1 Disassembly

a) Remove all the hexagon socket head cap

screws [2-2] fastening the main rotor casing and the bearing head. Support the foot of the main rotor casing using squared timbers.

b) Use jacking bolts to evenly push the block.

Once some gap is produced between the main rotor casing and the bearing head, use a scraper to detach the gasket from the bearing head and put it on to the main rotor casing side. When the alignment pins are disengaged, the bearing head is separated from the main rotor casing.

c) The main bearing [27-2] is lightly press fit into the bearing head. When removing the main bearing,

first use internal snap ring priers to remove the snap ring [29-2]. Then, either use a plastic block or other suitable element to push the bearing from the rotor side or use a special tool such as shown in Photo 051 to pull out the bearing. For the details of the special tool, refer to Section 5.5.2 in this manual.

Photo 050 Removing the Snap Ring Internal

Photo 051 Removing the Main Bearing

d) The unloader slide valve can be removed as an assembly by pulling it out from the bearing head

side. If no specific abnormality is found, no further disassembly is required.

e) The guide block stem [88-2] is screwed in from the bottom of the main rotor casing, and the guide

block [87-2] is engaged from the top. To replace the O-rings [89-2], remove the guide block stem.

5.4.15.2 Inspection

a) We recommend as well as the side bearings, unconditional exchange of the main bearings on the

occasion of the compressor overhaul, but for confirmation of the compressor condition and system operating condition, carefully check the sliding part metal surface of the main bearings.

If the metal surface is gray or any foreign matter is buried, also carefully check the wear of the rotor

shaft.

Photo 049 Loosening the Fastening Bolts

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b) Check the condition of the surface of the bearing head on the rotor side, where the discharge port is.

Properly mend the surface if any flaw is observed. If the entire surface has significant flaws, either the thrust bearing is defective or the end clearance adjustment is poor.

If oil compression has been caused during the operation, carefully and thoroughly check the area of

the discharge port in particular. If the continued use is in doubt at all, perform the penetrant testing (color check) to determine if it can be used or not.

c) With the unloader slide valve mounted in position, check the step height between the slide valve

and the main rotor casing surfaces. Usually, the surface of the slide valve should be lower than the surface of the main rotor casing.

If the top surface of the slide valve has a trace of hitting the rotor, the probable cause is that the slide

valve is worn or the rotor shaft/bearing is worn. Please contact our sales offices or service centers.

d) Check the properness of the slotted guide pin [68-2] at the tip of the unloader push rod [67-2] that

engages with the indicator cam [77-2].

5.4.16 Low-stage Bearing Head and Main Bearings

5.4.16.1 Disassembly

a) Unscrew and remove all the hexagon socket head cap screws [2-1]. b) Drive in the alignment pins [3-1] from the bearing head side to the main rotor casing side. c) Use the jacking screw holes on the flange to separate the bearing head and the main rotor casing. d) Separate them carefully along the shaft axis, as the unloader push rod [67-1] is engaged. e) The main bearing [27-1] can be easily pulled out by removing the snap ring [29-1] and then lightly

tapping it from the rotor side via a pad. Otherwise, use a special tool to pull it out.

f) Remove the slide valve as an assembly, using the same procedure as for the high-stage unit.

Carefully perform the work, as you are handling a heavy object.

Photo 052 Removing the Snap Ring Internal

Photo 053 Removing the Slide Valve

Assembly

5.4.16.2 Inspection

The inspection must be performed similarly to the case of the high-stage.

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5.5 Reassembly

 During the reassembly work, be very careful in selecting the correct replacement

O-rings of the specified standard, not to make a mistake regarding the size, material, for fixed use, for sliding use, etc. Using a wrong O-ring can lead to oil leak or other problems.

 Some gaskets are not symmetrically shaped. In such a case, be careful not to misplace

the gasket. If the gasket is misplaced, it can lead to a significant problem such as blocking any oil supply route on the casing.

After completing the disassembly and inspection procedures, start the assembly process. First, read again Section 5.1 "Precautions for Maintenance and Inspection" in this Chapter 5.

Before starting the assembly, check the replacement parts once again. Like gaskets, all O-rings that have been removed during the compressor disassembly must be replaced

with new ones. The reassembly sequence is mostly the reverse of the disassembly sequence. First of all, clean the

work bench and the tools to be used. Immediately prior to the assembly, use washing agent (e.g., kerosene, parts cleaner) oil to clean the

parts to be assembled, dry them with compressed air, and sufficiently apply lubricating oil, etc. For this, prepare a sufficient amount of clean lubricating oil for the reassembly. Also, apply oil on both sides of the gasket.

Because the assembly procedure is mostly similar between the high-stage and low-stage sides, the following sections provide explanations that are commonly used for both stages. For this purpose, the part number given in the common explanations will omit the distinction between high-stage and low-stage by means of a hyphenated suffix (the suffix of [**-1] for low-stage and [**-2] for high-stage part number will be omitted).

Please fully understand the details in this Section 5.5 for correct assembly work.

Table 5-7 Tightening Torques for Hexagon Socket Head Cap Screws

Torque unit

M10

M12

M14

M16

M20

M24

N･m

140

240

450

750

kgf cm

100

250

500

900

1400

2400

4500

7500

When fastening the hexagon socket head cap screws, use the tightening torque specified in the above table.

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Figure 5-13 Illustration of the Assembly Sequence (Example)

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5.5.1 Unloader Slide Valve and Guide Block

a) Attach two O-rings [89] on the guide block stem [88] and screw in the guide block stem securely

from the bottom of the casing. Then, mount the guide block [87] in the casing.

b) If the slide valve assembly has been disassembled, first make sure that the alignment position

between the slide valves [54] and [55] is accurately reproduced and then tighten the hexagon socket head cap screws [58] with spring washers [267] at the specified torque. The outer diameter of the spring washers used here is less than normal spring washers for hexagon socket head cap screws. So, be careful not to mix up with other washers.

c) After using a grind stone or fine sand paper to lightly finish the circumference of the assembly,

mount the assembly in the main rotor casing. Then, slowly push-in the push rod while aligning the groove of the slide valve with the guide block.

d) After it is assembled, hold the unloader push rod and move it for several times to check that it

moves smoothly. Then, carefully check the joint with the main rotor casing that there is no step between them. If there is a step, check it by reversing the orientation of the guide block first. If the step is still present, it should be due to imperfect assembling, and it must be reassembled.

◆ A slight step between the surfaces of the unloader slide valve and the main rotor casing is

allowed if the slide valve side is lower.

 If the step is such that the surface of the unloader slide valve is higher than the

surface of the main rotor casing, it is considered the problem of assembly. In such a case, it must not be left uncorrected. Be sure to reassemble it. Otherwise, the periphery of the rotor can make contact with the slide valve, resulting in a severe damage.

e) The low-stage slide valve assembly has an oil injection pipe guide [168] on the opposite side of the

push rod. Do not forget to install the O-ring [59] (Photo 055).

Photo 054 Installing the Slide Valve

(low-stage)

Photo 055 O-ring for the Oil Injection Pipe

Guide

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5.5.2 Bearing Head and Main Bearings

The main bearing (O-ring type) [27] is installed by a light press fit. a) Align the notch on the main bearing with the spring pin [14] that is driven in into the bearing head

[11], and then push it in with a pad. For the alignment, it is convenient to use a tool such as a guide bar.

b) After the bearing has been inserted, install the snap ring [29] to retain the bearing in position (Photo

056). Securely install the snap ring to be fully seated in the ring groove, by pushing the snap ring with a guide bar or the like, or by lightly hitting the guide bar with a hammer while placing the guide bar on the snap ring.

Photo 056 High-stage Bearing Head

Photo 057 Low-stage Bearing Head

c) On the low-stage bearing head [11-1], install the O-ring [197] in the part where the push rod passes

through. Then, use hexagon socket head cap screws [166-1] to install the O-ring gland [326-1].

When press fitting the bearing, it is recommended to prepare a collared plastic cylinder (spacer) that exactly fits inside the inner diameter of the bearing and also a collared weight that fits inside the plastic cylinder as shown in Figure 5-14. Then, hit the top of the weight for easy press fitting of the bearing. Instead of the above, special tools are also available from us for the high-stage and low-stage main and side bearings. These tools are similar to the above described weight, and the surface finish of which is improved to eliminate the need of a plastic spacer (Refer to Chapter 7, Section 7.5). You are welcome to place an order if necessary.

Figure 5-14 Example Tool for Press Fitting the Bearing

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Photo 058 Low-stage Rotor Casing and Bearing Head

5.5.3 Bearing Head and Main Rotor Casing

 Since the bearing head gasket [12] is not symmetrically shaped, carefully check the

orientation when installing the gasket.

 If you place the bearing head gasket by just hanging it on the stud bolts, the gasket

will protrude into the inside of the rotor casing when the casing is assembled. Apply sufficient amount of oil, etc. to the gasket to make it fully attached to the surface to prevent protruding upon the assembly.

a) In case of the low-stage, after fitting the unloader

push rod [67-1] into the hole of the bearing head [11-1], slide either the bearing head or the main rotor casing [1-1] to mate them together.

b) Lightly fastening two bolts [2] in symmetrical position.

Next, drive in the alignment pins [3] to fix the position by using a copper or an aluminum hammer.

c) After tightening the bolts [2], check that the bearing

head gasket is not protruding into the inside of the casing.

d) Also, move the slide valve back and forth to check

that it works normally.

e) As the full height of the high-stage main rotor casing

is lower than that of the bearing head, both centers will not be aligned when they are placed on the work bench. Therefore, either use a pedestal as used in the disassembly process or lift the rotor casing using a crane or other device to align the centers.

The assembly procedure after mating the both

casing flanges is same as the high-stage.

f) The bottom bolts that cannot be fastened on the work

bench are to be fastened later on.

 Be sure to check for possible protrusion of the gasket after the bearing head and

rotor casing have been assembled together. If you forget to check it out, it may lead to a measurement error in the end clearance adjustment process, as the gasket may be placed in between the rotor end and the bearing head surface. Furthermore, if the compressor is operated after the end clearance is erroneously adjusted and fixed in this condition, it may compromise the performance.

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5.5.4 Installing the Rotors

Note on the rotor profile of 3225**C

The rotor profile has been changed from the A profile to O profile from the production in November

1993. The biggest difference is the existence of lobe tip edge, as the A profile with lobe tip edge has been changed to the O profile, which has no lobe tip edge.

The rotor must be sufficiently reworked. If any slight flaw is observed on the shaft surface in the area of attaching the bearing or seal, use a sand paper to correct and finish the surface. After finishing the surface to attach the seal, apply protective tape on the surface.

Both the M rotor and F rotor have a specific engagement position, and the position is marked by carving. In order to make it easier to match the positions when the rotor is installed into the main rotor casing, a number is marked on the lobe tip: the M rotor has the marking on the discharge side, and the F rotor has the marking on the suction side.

Photo 059 Mating Mark on the M Rotor

Photo 060 Mating Mark on the F Rotor

a) Apply sufficient amount of lubricating oil on

the main bearing in the bearing head and on the bearing area of the rotor shaft.

b) While it is easier to mate the markings if the F

rotor is first installed into the casing, it is not a mistake to install the M rotor first, as shown in the photo to the right.

c) Regardless of which rotor is installed first, the

lobe of the M rotor with the carved marking of "1" must be set in between the F rotor’s lobes that are marked "1" and "2". As it affects smooth engagement of the lobes as well as the balance, be sure to mate the markings as described above.

 As the circumference of the rotor is touching the main rotor casing in this condition,

any rotation of the rotor should be kept to the minimum required. Otherwise, the lobes tip of the rotor may be worn.

Photo 061 Installing the M Rotor

2202MYJE-MY-C8-N_2018.02.

Chapter 5 Maintenance and Inspection

Compound 2-stage Screw Compressor 3225**C 5.5 Reassembly

5-44

5.5.5 Suction Cover and Side Bearings

a) Similarly to the main bearing, the side bearing (O-ring type) [28] is machined to the size that will

allow light press fitting to the suction cover. Press fit the bearing by aligning the notch position of the bearing with the spring pin [8] for positioning the bearing driven-in on the suction cover. During the press fitting process, check that the notch position of the bearing is at the pin position. If the position has been shifted, pull out the bearing and try the press fitting process again.

b) After the bearing has been installed, install the snap ring [29] to retain the bearing. Make sure that

the snap ring is fully seated in the ring groove either by pushing the ring with a guide bar or tapping the head of the guide bar while applying the bar on the ring.

Photo 062 Installing the High-stage Side

Bearing

Photo 063 Installing the High-stage Snap Ring

Photo 064 Installing the Low-stage Bearing

Photo 065 Installing the Low-stage Snap Ring

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