Industrial Maintenance and Troubleshooting, 4th Edition by American Technical Publishers

FOURTH EDITION

Denis Green Jonathan F. Gosse

Industrial Maintenance and Troubleshooting contains procedures commonly practiced in industry and the trade. Specific procedures vary with each task and must be performed by a qualified person. For maximum safety, always refer to specific manufacturer recommendations, insurance regulations, specific job site and plant procedures, applicable federal, state, and local regulations, and any authority having jurisdiction. The material contained is intended to be an educational resource for the user. American Technical Publishers assumes no responsibility or liability in connection with this material or its use by any individual or organization.

American Technical Publishers Editorial Staff Editor in Chief: Jonathan F. Gosse Vice President — Editorial: Peter A. Zurlis Assistant Production Manager: Nicole D. Bigos Technical Editor: Julie M. Welch Supervising Copy Editor: Catherine A. Mini Copy Editor: Jeana M. Platz Editorial Assistant: Erin E. Magee Lauren D. Bedillion Cover Design: Sarah E. Kaducak

Art Supervisor: Sarah E. Kaducak Illustration/Layout: Christopher S. Gaddie Nicholas G. Doornbos Richard O. Davis Nicholas W. Basham Steven E. Gibbs Bethany J. Fisher Digital Media Manager: Adam T. Schuldt Digital Resources: Robert E. Stickley Mark A. Passine Tim A. Miller

The American National Standards Institute and ANSI are registered trademarks of American National Standards Institute, Inc. American Petroleum Institute and API are registered trademarks of the American Petroleum Institute. American Society of Mechanical Engineers and ASME are registered trademarks of the American Society of Mechanical Engineers. ASTM International is a registered trademark of the American Society for Testing and Materials. CSA Group is a registered trademark of the Canadian Standards Association. IEEE is a registered trademark of the Institute of Electrical and Electronics Engineers, Inc. Kevlar is a registered trademark of E. I. du Pont de Nemours and Company. The National Electrical Code, NEC, National Fire Protection Association, and NFPA are registered trademarks of the National Fire Protection Association, Inc. The National Electrical Manufacturers Association and NEMA are registered trademarks of the National Electrical Manufacturers Association. The National Institute for Occupational Safety and Health and NIOSH are registered trademarks of the U.S. Department of Health and Human Services agency of the United States government. O*NET is a registered trademark of the U.S. Department of Labor, Employment and Training Administration. SAE International is a registered trademark of SAE International Corporation. TLV is a registered trademark of the American Conference of Governmental Industrial Hygienists, Inc. UL is a registered trademark of Underwriters Laboratories, LLC. U.S. Green Building Council is a registered trademark of the U.S. Green Building Council. WaterSense is a trademark of UICO, INC. QuickLink, Quicklinks, Quick Quiz, and Quick Quizzes are trademarks of American Technical Publishers.

Acknowledgements

The authors and publisher are grateful for the photographs and technical information provided by the following companies and organizations.

Ansell Edmont Industrial, Inc. Atlas Fire & Safety Equipment, LTD Baldor Electric Company Carrier Corporation Chicago Pneumatic Cleaver-Brooks Danfoss Drives Daymark® Safety Systems Dwyer Instruments, Inc. eMaint, a Fluke Company Emerson Process Management Emission Database for Global Atmosphere Research Environmental Protection Agency (EPA) FLIR Systems, Inc. Fluke Corporation Harrington Hoists, Inc. Henry Valve Co. Integrus Architecture Kewanee Boiler Manufacturing Co., Inc. Lab Safety Supply, Inc. LEDtronics, Inc. LEESON Electric Corporation The Lincoln Electric Company Loctite Corporation Miller Fall Protection

Mine Safety Appliances Co. North by Honeywell North Safety Products NREL, Northern Power Systems Power Team, Division of SPX Corporation Predict-DLI Robinair Division, SPX Corporation Salisbury Saylor-Beall Manufacturing Company SEW-Eurodrive, Inc. SKF Condition Monitoring SKF USA Inc. SPG Solar, Inc. Spirax Sarco, Inc. SPX Robinair Tecumseh Products Company The Timken Company The Trane Company UE Systems, Inc. Unico, Inc. U.S. Dept. of Labor US Environmental Protection Agency Wendy’s International Inc. Yellow Jacket Div., Ritchie Engineering Co., Inc.

Contents

Maintenance and Troubleshooting Principles________________________ 2

Workplace Safety ______________________________________________________38

Printreading ____________________________________________________________86

Service and Repair Principles _________________________________________ 132

Mechanical Drives ___________________________________________________ 162

SECTION 1.1 — Maintenance Personnel _____________________________________________________4 SECTION 1.2 — Unscheduled Maintenance __________________________________________________9 SECTION 1.3 — Preventive Maintenance __________________________________________________ 10 SECTION 1.4 — Predictive Maintenance ___________________________________________________ 17 SECTION 1.5 — Maintenance and Repair Management ______________________________________ 19 SECTION 1.6 — Troubleshooting _________________________________________________________ 30

SECTION 2.1 — Safety Planning _________________________________________________________ SECTION 2.2 — Safety Regulations_______________________________________________________ SECTION 2.3 — Personal Protective Equipment _____________________________________________ SECTION 2.4 — Fire Safety _____________________________________________________________ SECTION 2.5 — Electrical Safety _________________________________________________________ SECTION 2.6 — Special Procedures ______________________________________________________ SECTION 2.7 — Industrial Hygiene _______________________________________________________ SECTION 2.8 — Emergencies ___________________________________________________________

40 40 44 54 57 63 74 80

SECTION 3.1 — Prints _________________________________________________________________ 88 SECTION 3.2 — Object Representation ___________________________________________________ 96 SECTION 3.3 — Maintenance Prints _____________________________________________________ 105 SECTION 3.4 — Additional Documentation _______________________________________________ 122

SECTION 4.1 — Mechanics ____________________________________________________________ SECTION 4.2 — Heat _________________________________________________________________ SECTION 4.3 — Materials _____________________________________________________________ SECTION 4.4 — Fastening _____________________________________________________________ SECTION 4.5 — Sealing and Coating ____________________________________________________ SECTION 4.6 — Tools _________________________________________________________________

SECTION 5.1 — Mechanical Drive Types _________________________________________________ SECTION 5.2 — Lubricants_____________________________________________________________ SECTION 5.3 — Ancillary Components __________________________________________________ SECTION 5.4 — Mechanical Drive Predictive Maintenance __________________________________ SECTION 5.5 — Mechanical Drive Preventive Maintenance __________________________________ SECTION 5.6 — Mechanical Drive Troubleshooting ________________________________________ CASE STUDY ______________________________________________________________________

134 142 145 147 156 159

164 180 183 189 196 208 213

Electrical Systems ____________________________________________________ 214

Electronic Systems __________________________________________________ 284

Refrigeration Systems ________________________________________________ 320

Boiler Systems________________________________________________________ 364

SECTION 6.1 — Electrical Parameters____________________________________________________ SECTION 6.2 — Electrical Circuits _______________________________________________________ SECTION 6.3 — Power Distribution ______________________________________________________ SECTION 6.4 — Electrical Test Instruments ________________________________________________ SECTION 6.5 — Power Quality ________________________________________________________ SECTION 6.6 — Electrical Devices_______________________________________________________ SECTION 6.7 — Electrical System Printreading ____________________________________________ SECTION 6.8 — Electrical System Maintenance ____________________________________________ SECTION 6.9 — Electrical System Troubleshooting _________________________________________ CASE STUDY ______________________________________________________________________

SECTION 7.1 — Semiconductors ________________________________________________________ SECTION 7.2 — Solid-State Devices _____________________________________________________ SECTION 7.3 — Electronic System Printreading ____________________________________________ SECTION 7.4 — Electronic System Maintenance ___________________________________________ SECTION 7.5 — Electronic System Troubleshooting _________________________________________ SECTION 7.6 — Programmable Logic Controllers __________________________________________ SECTION 7.7 — Programmable Logic Controller Maintenance _______________________________ SECTION 7.8 — Programmable Logic Controller Troubleshooting _____________________________ CASE STUDY ______________________________________________________________________

SECTION 8.1 — Refrigeration Principles __________________________________________________ SECTION 8.2 — Refrigeration System Components _________________________________________ SECTION 8.3 — Refrigeration Control Systems ____________________________________________ SECTION 8.4 — Specialty Refrigeration Systems ___________________________________________ SECTION 8.5 — Refrigeration System Maintenance ________________________________________ SECTION 8.6 — Refrigeration System Troubleshooting ______________________________________ SECTION 8.7 — Refrigerant Regulations _________________________________________________ CASE STUDY ______________________________________________________________________

SECTION 9.1 — Boiler System Overview _________________________________________________ SECTION 9.2 — Boiler Fittings and Accessories ____________________________________________ SECTION 9.3 — Combustion and Draft __________________________________________________ SECTION 9.4 — Boiler Operation Procedures _____________________________________________ SECTION 9.5 — Boiler System Printreading _______________________________________________ SECTION 9.6 — Boiler System Maintenance ______________________________________________ SECTION 9.7 — Boiler System Troubleshooting ____________________________________________ CASE STUDY ______________________________________________________________________

216 220 224 228 237 243 255 262 266 281

286 287 297 298 302 307 313 314 319

322 325 336 339 347 348 358 362

366 374 385 393 398 402 410 413

Contents

HVAC Systems _______________________________________________________ 414

Fluid Power Systems _________________________________________________ 462

Efﬁciency and Sustainability _________________________________________ 512

SECTION 10.1 — Comfort _____________________________________________________________ SECTION 10.2 — System Operation _____________________________________________________ SECTION 10.3 — Forced-Air System Configurations________________________________________ SECTION 10.4 — HVAC System Components _____________________________________________ SECTION 10.5 — Control Signals _______________________________________________________ SECTION 10.6 — Control Systems ______________________________________________________ SECTION 10.7 — HVAC System Maintenance _____________________________________________ SECTION 10.8 — HVAC System Troubleshooting __________________________________________ CASE STUDY ______________________________________________________________________

SECTION 11.1 — Hydraulic Systems_____________________________________________________ SECTION 11.2 — Hydraulic System Components __________________________________________ SECTION 11.3 — Fluid Power System Printreading _________________________________________ SECTION 11.4 — Hydraulic System Maintenance __________________________________________ SECTION 11.5 — Hydraulic System Troubleshooting________________________________________ SECTION 11.6 — Pneumatic Systems ____________________________________________________ SECTION 11.7 — Pneumatic System Components __________________________________________ SECTION 11.8 — Pneumatic System Maintenance _________________________________________ SECTION 11.9 — Pneumatic System Troubleshooting _______________________________________ CASE STUDY ______________________________________________________________________

SECTION 12.1 — Facility Efficiencies ____________________________________________________ SECTION 12.2 — Energy Auditing ______________________________________________________ SECTION 12.3 — Plan Implementation ___________________________________________________ SECTION 12.4 — System Efficiency Measures _____________________________________________

416 423 428 432 442 444 447 452 460

464 469 484 490 494 498 503 507 508 510

514 526 528 531

APPENDIX ____________________________________________________________ 549 GLOSSARY ___________________________________________________________ 569 INDEX ___________________________________________________________ 593

Learner Resources • • • •

Quick Quizzes™ Illustrated Glossary Flash Cards Maintenance Forms

• Troubleshooting Checklists • Media Library • ATPeResources.com

Introduction

Industrial Maintenance and Troubleshooting focuses on developing the maintenance, troubleshooting, and repair abilities of multiskilled maintenance personnel. The book covers general principles and methods for safe, effective, and efficient facility maintenance. It then follows with seven chapters, each dedicated to a particular facility system commonly encountered by maintenance personnel. The overall operation and major components of each system are explained, along with common maintenance problems and troubleshooting strategies. This edition features the following: • A new chapter, Efficiency and Sustainability, that covers conservation and cost-saving procedures in facility maintenance and management • Full-color photos and illustrations that enhance the technical content • A new chapter on essential printreading skills typically required for maintenance technicians and the use of other types of documentation • Chapters that have been divided into sections, with learning objectives and checkpoint questions, to maximize instructional flexibility

Features

System diagrams explain the overall operation of common industrial systems.

Safety Tips add valuable information about safe working practices.

Tech Tips enhance technical information with supplementary maintenance advice.

Detailed illustrations clearly show the design and function of system components.

Photographs illustrate common system components and maintenance procedures.

Learner Resources

Industrial Maintenance and Troubleshooting online learner resources are self-study tools that reinforce the content covered in the book. These online resources can be accessed using either of the following methods: • Key ATPeResources.com/QuickLinks into a web browser and enter QuickLinks™ Access code . • Use a Quick Response (QR) reader app to scan the QR Code with a mobile device.

The online learner resources include the following: • Quick Quizzes™ that provide interactive questions for each section, with embedded links to highlighted content within the textbook and to the Illustrated Glossary • Illustrated Glossary that serves as a helpful reference to commonly used terms, with selected terms linked to textbook illustrations • Flash Cards that provide a self-study/review of common terms and their definitions • Maintenance Forms that fulfill common recordkeeping requirements and can be printed for use in the field • Troubleshooting Checklists that include numerous suggestions for possible causes of and related tests for common industrial equipment problems • Media Library that consists of videos and animations that reinforce textbook content • Internet Resources that provide access to additional resources to support continued learning

Maintenance and Troubleshooting Principles SECTION 1.1 — MAINTENANCE PERSONNEL • Identify the types of facilities that employ maintenance personnel. • List and describe common classiﬁcations of maintenance personnel. • Explain the importance of interpersonal skills for maintenance personnel. • List ways in which maintenance personnel work toward advancement in their ﬁeld. SECTION 1.2 — UNSCHEDULED MAINTENANCE • Describe unscheduled maintenance and why it is not ideal. • Compare emergency work and breakdown maintenance. SECTION 1.3 — PREVENTIVE MAINTENANCE • Describe the goal of preventive maintenance (PM). • Compare the three main types of scheduled maintenance. • Explain the role of maintenance technicians in operational maintenance. • Detail the process for developing a new PM system. SECTION 1.4 — PREDICTIVE MAINTENANCE • Describe the goal of predictive maintenance (PdM). • List types of information collected for PdM analysis. • Identify the necessary investments when implementing a PdM program. • Describe disadvantages of PdM programs.

SECTION 1.5 — MAINTENANCE AND REPAIR MANAGEMENT • Describe how work orders and work priorities are used to organize maintenance tasks. • Describe logbooks and how they are useful maintenance and troubleshooting resources. • List common features of computerized maintenance management systems (CMMSs). • Identify ways in which mobile devices are useful during maintenance and troubleshooting. • Explain the importance of inventory management. • Explain the necessity of evaluating maintenance costs to maximize efﬁciency and value. • Identify circumstances that may require out-ofplant services. SECTION 1.6 — TROUBLESHOOTING • Describe the steps of a comprehensive troubleshooting methodology. • Describe troubleshooting tools commonly used when isolating a problem. • Explain why systems thinking is a necessary skill for troubleshooting. • Compare open-loop and closed-loop systems. • Describe types of outside help available when troubleshooting. • Describe the role of troubleshooting in PM.

Chapter 1 â&#x20AC;&#x201D; Maintenance and Troubleshooting Principles 3

CHAPTER

Maintenance personnel specialize in the maintenance, troubleshooting, and repair of building systems and process equipment in a wide variety of industrial facilities and commercial buildings. Maintenance personnel use preventive and predictive maintenance to minimize equipment malfunctions and failures and maximize efficiency in industrial facilities. Preventive maintenance is regular maintenance work required to keep equipment in peak operating condition. Predictive maintenance is the monitoring of equipment conditions and characteristics to predict potential problems, which can then be prevented. Troubleshooting skills are used to identify the cause of an equipment malfunction or failure and then determine the best remedy.

Learner Resources ATPeResources.com/QuickLinks Access Code:

4â&#x20AC;&#x192; INDUSTRIAL MAINTENANCE AND TROUBLESHOOTING

SECTION 1.1

MAINTENANCE PERSONNEL Companies or institutions commonly employ their own personnel to perform maintenance tasks in a facility. The duties and responsibilities of these workers are determined by the structure of the maintenance organization. Maintenance organizations range in size from one individual in a small organization to many individuals in a large organization.

only by millwrights. In some organizations, especially larger ones, this is still the case. However, the responsibilities of some trades have expanded into additional areas. For example, as the use of steam for heating and powering industrial processes has changed, stationary engineers have become responsible for all heating, cooling, and industrial process equipment in addition to operating boilers. Therefore, maintenance personnel are broadly classified as specialists or multiskilled. INDUSTRIAL MAINTENANCE

Workplaces Maintenance personnel are employed in a variety of building types, including commercial and industrial. Commercial buildings include schools, office buildings, retail stores, and hotels. Industrial buildings include facilities for food processing, manufacturing, refining, mining, assembly, and other heavy processes. Maintenance work for commercial and industrial buildings is similar and includes various types of mechanical, HVAC, electrical, and other building systems. However, industrial buildings often require larger or more sophisticated equipment. See Figure 1-1. Also, industrial facilities typically house a lot of equipment related to the processing or production of products. For example, food processing facilities include washers, mixers, ovens, conveyors, packaging machines, and other processing equipment. The maintenance of this equipment is also the responsibility of the maintenance staff. While all maintenance work should be performed promptly, this can be especially critical in industrial facilities. For example, if an HVAC system in a commercial office building fails, workers may become uncomfortable, but they can usually continue to work until it is repaired. In an industrial facility, however, downtime due to equipment maintenance or breakdowns can be extremely costly because it stops production. This results in a loss of worker productivity and possible spoilage of products. Downtime costs could be thousands of dollars or more per minute, so a failure in an industrial setting must be corrected immediately.

Maintenance Skills Over the years, the maintenance trades have changed with the needs of industry. Maintenance personnel in the past were trained and hired to perform maintenance in a specific craft. For example, welding repairs were performed only by welders, and machines were installed

Figure 1-1. Maintenance technicians in industrial facilities work on a variety of large and sophisticated equipment.

Specialist maintenance personnel have a great amount of expertise in one craft. Multiskilled maintenance personnel have expertise in several crafts. The structure of a maintenance organization is determined by the classification of maintenance personnel. See Figure 1-2. Maintenance organizations with specialist maintenance personnel have a lead person for each craft. Maintenance organizations with multiskilled maintenance personnel have a lead person for each shift or crew.

Chapter 1 — Maintenance and Troubleshooting Principles 5

MAINTENANCE ORGANIZATIONS CHIEF ENGINEER ASSISTANT CHIEF ENGINEER

ELECTRICAL LEAD PERSON

MECHANICAL LEAD PERSON

WELDING LEAD PERSON

INSTRUMENTATION LEAD PERSON

STEAM PLANT LEAD PERSON

OFFICE SUPPORT LEAD PERSON

ELECTRICIAN

MILLWRIGHT

WELDER

INSTRUMENTATION TECHNICIAN

OPERATING ENGINEER

OFFICE SUPPORT PERSON

ELECTRICIAN

MILLWRIGHT

WELDER

INSTRUMENTATION TECHNICIAN

OPERATING ENGINEER

OFFICE SUPPORT PERSON

ELECTRICIAN

MILLWRIGHT

WELDER

INSTRUMENTATION TECHNICIAN

OPERATING ENGINEER

OFFICE SUPPORT PERSON

SPECIALIST CHIEF ENGINEER

FIRST SHIFT LEAD PERSON

SECOND SHIFT LEAD PERSON

THIRD SHIFT LEAD PERSON

OFFICE SUPPORT LEAD PERSON

CREW MEMBER

OFFICE SUPPORT PERSON

CREW MEMBER

OFFICE SUPPORT PERSON

CREW MEMBER

OFFICE SUPPORT PERSON

MULTISKILLED Figure 1-2. The structure of a maintenance organization is determined by the classification of maintenance personnel.

Multiskilled maintenance technicians are becoming more popular in industry because they often provide flexibility and cost effectiveness in maintenance organization. With more individuals qualified for each task, it is often easier to assign maintenance work and have necessary maintenance staff available when needed. Additionally, multiskilled maintenance personnel may be more effective at troubleshooting. For example, an electrical specialist investigating a boiler malfunction may be familiar with only the electrical system and overlook a mechanical problem with the water-level controller. However, a multiskilled maintenance technician that is familiar with many aspects of boiler operation may identify the problem more quickly.

Even among those with a variety of skills, it is common for each technician to have strengths in certain crafts. For example, one member of a maintenance crew might specialize in electrical work while another might be a better welder. However, each member is qualified to perform a variety of maintenance tasks. If a critical system malfunctions, each must be able to address the problem quickly to minimize downtime. Various maintenance personnel jobs are defined by the federal Standard Occupational Classification (SOC) system and identified by job titles and numbers. See Figure 1-3. This classification system is also used by the US Department of Labor’s O*NET® OnLine database, which details the knowledge, skills, abilities, and tasks required of each job.

6 INDUSTRIAL MAINTENANCE AND TROUBLESHOOTING

SELECTED MAINTENANCE JOB TITLES Job Title

SOC Number*

First-Line Supervisors/Managers of Mechanics, Installers, and Repairers

49-1011

Electric Motor, Power Tool, and Related Repairers

49-2092

Electrical and Electronics Repairers, Commercial and Industrial Equipment

49-2094

Control and Valve Installers and Repairers, Except Mechanical Door

49-9012

Heating, Air Conditioning, and Refrigeration Mechanics and Installers

49-9021

Industrial Machinery Mechanics

49-9041

Maintenance Workers, Machinery

49-9043

Millwrights

49-9044

Riggers

49-9096

Helpers — Installation, Maintenance, and Repair Workers

49-9098

Installation, Maintenance, and Repair Workers, All Others

49-9099

Stationary Engineers and Boiler Operations

51-8021

* 2010

Anyone a technician works with or who asks a maintenance technician for help with technical problems should be treated as a valued customer. Clear and concise communication is the key to effective customer service during maintenance and troubleshooting. COMPUTER LITERACY

Standard Occupational Classification (SOC) system

Figure 1-3. Various maintenance-related jobs are defined in the SOC system.

Computer and Electronic Communication Skills Computer literacy is a necessary skill for all technicians. Equipment documentation is increasingly available and accessed as electronic files. Also, some equipment is networked or otherwise connected to computers for programming, setup, monitoring, or troubleshooting. See Figure 1-4. Networking can be local (inside the building), regional, or worldwide, with equipment being monitored from anywhere with an Internet connection. As computerized systems and capabilities evolve, ongoing learning and skill upgrades are required. This will also involve computer security, since it is possible for criminals to hack into computer systems to steal data or to take over the operation of equipment to damage or destroy it.

Interpersonal Skills Interpersonal skills are as important as technical skills for maintenance personnel. Interpersonal skills are strategies and actions that allow an individual to communicate effectively with others in a variety of situations. This is also referred to as customer service.

Figure 1-4. Electronic documentation is becoming standard, which requires technicians to develop computer and electronic communication skills.

Effective communication requires active listening followed by careful speaking. See Figure 1-5. Active listening requires focusing on the customer’s problems. Technicians let customers speak freely without interruption or judgement to learn the exact problem and its possible causes. For example, it is important to determine when the problem began and any other service the equipment has received recently. Technicians should take notes, then repeat what the technician understands the customer said. Once the customer and technician agree that they understand each other, the technician works through the troubleshooting steps to learn the cause of the problem. If the repair is simple, the technician usually proceeds with the work and informs the customer of the repair. If the repair is complicated, costly, or might result in excessive downtime, the technician should explain the options with the customer and receive input on how to proceed. For example, a decision may need to be made whether to rebuild or replace a piece of equipment. Clear communication eliminates misunderstandings and reduces troubleshooting time.

Chapter 1 — Maintenance and Troubleshooting Principles

• What is the history of the problem? When did the problem start?

Technicians must not lose their tempers or become angry when helping an upset customer. They can prevent his by using controlled breathing, such as counting breaths, or other stress relieving exercises while communicating with angry customers. After a stressful encounter with an angry customer, a technician may need to take a short break or complete a routine work-related activity.

• What else was happening at the time or prior to when the problem was noticed?

Written Communication Skills

INVESTIGATING PROBLEMS WITH CUSTOMERS • Talk to the operator or owner of the equipment. • What is the normal operation? What is the current operation?

• List all the symptoms of the problems. • Are there any maintenance or troubleshooting equipment records to study? • Using manuals or other resources, confirm your understanding of the normal operation of the equipment and its relationship to the rest of any larger system. • If possible, operate the equipment. (What if nothing seems wrong, but the operator believes there is a problem?) • Write or create a simple statement of the problem. Include only what is wrong without possible solutions. Figure 1-5. Clear communication between maintenance personnel and the equipment operator is necessary for efficient troubleshooting.

When repairs are costly and take longer than expected, customers can become angry. Dealing with an angry customer is a type of troubleshooting and involves the following process: 1. Always greet customers politely and respectfully and focus on solving the problem. 2. Allow angry customers to vent their frustrations without arguing with them or making them feel threatened or foolish. 3. When they calm down, restate the problem and listen to their response. Keep doing so until they agree that the problem is clearly understood. Write a summary of the problem. 4. Explain the possible solutions and help customers understand the pros and cons of each possible solution. 5. When the solution is agreed upon, make the repair or changes as quickly and as completely as possible. Then, follow up to see if the problem is solved and that the customers are satisfied. If possible, fix the condition that caused the problem. Always thank customers. Keep thorough records, and document the situation carefully. Always be respectful.

Once a repair is completed, technicians must carefully record the problem, causes, and solutions in the appropriate reports. See Figure 1-6. A description of the troubleshooting procedure, including summaries of the wrong paths taken, may be appropriate to include. The technician might also recommend improved maintenance procedures to prevent the problem from recurring. Compiling these records requires excellent research, interviewing, and verbal and written communication skills. Recorded information should be concise so that other technicians can quickly follow the procedure and reach the conclusion. The information also must be complete enough to prevent others from having to repeat unnecessary testing if the same problem occurs.

Written reports generated by maintenance personnel must be clear and organized.

8â&#x20AC;&#x192; INDUSTRIAL MAINTENANCE AND TROUBLESHOOTING

EXAMPLE TROUBLESHOOTING REPORT Technician(s): Date and Time: System/Equipment: Problem:

Symptoms:

Troubleshooting:

Corrective Action:

Joe Smith and Helen Miller Aug 18th, 8:25 am

Location:

West loading dock

Overhead door Overhead door will not open The door controls energize the motor, and the door appears to shift slightly, but not open. Door operated normally the day before. The voltage to the motor is within spec. Current draw is high. Motor overloaded? Inspected drive chain: appears normal, but relubricated. Almost due for maintenance anyway. Inspected door track. Found damage to track that prevented door rollers from traveling. Damage may have been from being hit by a forklift. Bent the track back into position and tested door to ensure that it operates. It does, but track is still slightly deformed. Recommend replacing section of door roller track completely for smoothest operation.

Other Notes:

Consider building a guard around the lower section of door track to prevent similar damage in the future.

Figure 1-6. Technicians must be able to write a clear, concise, and complete troubleshooting report. Future maintenance and troubleshooting efficiency may depend on this information.

Advancement in Maintenance Trades Successful maintenance personnel practice lifelong learning and continuous improvement. Once basic skills are mastered, higher levels of skill mastery are required. Maintenance personnel make the most of each task by evaluating and refining strategies and skills. In addition, new materials, tools, and equipment are developed regularly. The ability to adapt as the industry changes is crucial for success. Reading trade publications, attending classes and seminars, and participating in professional organizations are activities that provide valuable information on current topics and trends. New skills are required to remain current with advancing technology and grow in the maintenance trades.

CHECKPOINT

SECTION 1.1

1. Why are industrial facilities more maintenance intensive than commercial facilities? 2. Why is it becoming more popular to employ multiskilled maintenance personnel? 3. Why is some equipment connected to computers? 4. How should maintenance personnel behave when confronted with upset customers? 5. What types of skills are typically needed for technicians to complete their written reports? 6. Why is it important for maintenance personnel to continually develop and improve their skills?

Chapter 1 — Maintenance and Troubleshooting Principles 9

Breakdown Maintenance

SECTION 1.2

UNSCHEDULED MAINTENANCE Unscheduled maintenance is immediate service that is required due to a failure. Unscheduled maintenance should be minimized, though in many cases it may be necessary. This type of work may disrupt regularly scheduled maintenance, as some unscheduled tasks must be handled immediately. Unscheduled maintenance includes emergency work and breakdown maintenance, which differ based on whether the failed equipment receives regular maintenance.

Emergency Work Emergency work is unscheduled service to correct an unexpected failure on equipment that receives regular maintenance. The regular maintenance, such as cleaning or lubrication, is intended to prevent most failures. However, problems can still occur due to accidents, changing conditions, or previously undetected abnormalities. Emergency work orders are issued to repair damaged equipment immediately. See Figure 1-7. Keeping a log of emergency work provides information that can improve maintenance procedures or equipment design by identifying common equipment problems.

Breakdown maintenance is unscheduled service on failed equipment that has not received regular maintenance. Breakdown maintenance is the least sophisticated maintenance work, but it is often appropriate for equipment that is inexpensive and noncritical to facility operations. For example, light bulbs are serviced using breakdown maintenance because it is less costly to replace a bad bulb than to predict a bulb failure by testing. However, if applied to the wrong equipment, breakdown maintenance can be expensive. For example, centrifugal pump bearings should be monitored and replaced according to manufacturer recommendations because excessively worn bearings that operate until failure can result in costly shaft assembly replacement and/or pump damage.

CHECKPOINT

SECTION 1.2

1. Why is unscheduled maintenance not ideal? 2. What are common reasons for emergency work? 3. What is an example of work best done with breakdown maintenance?

EMERGENCY WORK ORDERS

No. 821463

EMERGENCY WORK ORDER MACHINE

Date

Time Called

Mechanical

Time Arrived

Employee

Time Finished

Other

Machine Downtime Production Time Lost Number of Employees Affected by Shutdown Reason for Stoppage

Maintenance Technician Production Supervisor

Figure 1-7. Emergency work orders are issued to repair damaged or malfunctioning equipment immediately.

10 INDUSTRIAL MAINTENANCE AND TROUBLESHOOTING

SECTION 1.3

PREVENTIVE MAINTENANCE Preventive maintenance (PM) is scheduled work required to keep equipment in peak operating condition. When in peak operating condition, equipment operates as designed, producing high-quality output at maximum efficiency. PM minimizes equipment malfunctions and failures and maintains optimum production efficiency and safety conditions in the facility. This results in increased service life, reduced downtime, and greater overall plant efficiency. PM tasks and frequency for each piece of equipment are determined using manufacturer specifications, equipment manuals, trade publications, and worker experience.

Scheduled Maintenance Scheduled maintenance is work that is planned and scheduled for completion. See Figure 1-8. Scheduled maintenance is performed to minimize emergency work and ensure reliable and efficient operations. Scheduled maintenance work includes periodic maintenance, corrective work, and project work.

Periodic Maintenance. Periodic maintenance is work completed at specific intervals. Periodic maintenance is scheduled based on time, such as daily, weekly, monthly, or quarterly, or according to equipment operating hours. Periodic maintenance tasks commonly include the following: • inspection of equipment for conditions, such as unusual noise, leaks, or excessive heat, that indicate potential problems • lubrication of equipment at scheduled intervals • adjustments and parts replacement to maintain equipment in proper operating condition • checking the electrical, hydraulic, and mechanical systems of operating equipment Periodic work orders specific to one piece of equipment or several pieces of equipment are scheduled at specific intervals throughout the year. If a computerized system is used, a master schedule can be created with work orders projected automatically by day, week, month, or year. TECH TIP As the size and complexity of a maintenance organization increases, work planning must become more formal and be scheduled.

SCHEDULED MAINTENANCE LISTS

RF Industries Week 2 Date 7/12 7/12 Total

Task No. BEARING-REPLACE BEARING-REPLACE

Week 3 Date 7/19 7/19 7/19 7/19 7/19 Total

Task No. WO No. BEARING-REPLACE – BEARING-REPLACE – EXTRD-MTR-BELT-3M – EXTRDSCREW-BRNG-6M – EXTRDSCREW-BRNG-6M –

Week 4 Date 7/26 7/26 7/26 7/26 Total

Task No. BEARING-REPLACE FKLFT-PM-1M BEARING-REPLACE DIE-CLEAN

WO No. Equipment No. – MOTOR-EXTRUD1-LN1 – MOTOR-EXTRUD1-LN1

WO No. – – – –

Cost Center 7001 7001

Expense Class MECH MECH

Hours 2.0 2.0 4.0

Equipment No. MOTOR-EXTRUD1-LN1 MOTOR-EXTRUD1-LN1 MOTOR-EXTRD2-LN2 SCREW-EXTRD1-LN2 SCREW-EXTRD1-LN2

Cost Center 7001 7001 7001 7001 7001

Expense Class MECH MECH MECH MECH MECH

Hours 2.0 2.0 2.0 4.0 4.0 14.0

Equipment No. MOTOR-EXTRUD1-LN1 -MULTITASKMOTOR-EXTRUD1-LN1 DIE-LN2

Cost Center 7001

Expense Class MECH COMB MECH MECH

Hours 2.0 6.0 2.0 2.0 12.0

7001 7001

Datastream Systems, Inc.

Figure 1-8. A scheduled maintenance list can help determine parts and personnel needed in the future.

Chapter 1 — Maintenance and Troubleshooting Principles 11

Corrective Work. Corrective work is the repair of a known problem before a breakdown occurs. Corrective work is requested after a problem is discovered during periodic inspections or while performing other maintenance tasks. See Figure 1-9. Information on the work completed, supplies used, cause of problem, costs, and time for completion is recorded in the PM system when corrective work is completed. Project Work. Project work is work on long-term projects that require advanced planning and more time than typical maintenance tasks. Project work commonly includes rebuilding or modifying equipment, renovating structures, or installing new equipment. TECH TIP Maintenance personnel should hold regular staff meetings to address operations, planned projects, ongoing problems, and safety concerns. Safety topics should include updates on applicable regulations, reminders of proper procedures and PPE usage, and discussion of any recent accidents along with how to prevent similar accidents in the future.

Operational Maintenance Operational maintenance is the monitoring of running equipment to ensure that it is functioning correctly. Previously, this was done by recording and studying equipment operating information, such as condenser pressures and temperatures. This information was recorded in a logbook and studied for changes. See Figure 1-10. These ongoing records allowed technicians to monitor equipment operation and learn the operating characteristics of specific equipment and systems. Long-term trends can also be detected from logbook entries. For example, the temperature difference between the water entering and leaving a condenser may change from 10°F to 8°F over several months. This slow change may indicate dirty condenser tubes that prevent the transfer of heat from the condenser to the cooling water. Such a problem increases operating costs and reduces the cooling capability of the system, but it does not threaten the chiller with immediate, serious damage. Therefore, inspection and cleaning of the tubes may be scheduled for a convenient time when the chiller can be taken out of service.

CORRECTIVE WORK ORDERS

Figure 1-9. A corrective work order specifies repair work needed before a breakdown occurs.

12 INDUSTRIAL MAINTENANCE AND TROUBLESHOOTING

MAINTENANCE LOGS

CHILLER AIR CONDITIONING AND REFRIGERATION LOG NUMBER

Crete Compressors

5486/93

COMPRESSOR

INFORMATION LOGGED HOURLY/DAILY

DATE OR TIME

OUTSIDE TEMP (°F)

Bearing Temp (°F)

MOTOR

SIZE

GEAR OIL

CHILLER

Amps Volts Press. Temp

Oil

Temp Press. Level Reservoir Temp Leaving PSI Cooler

PSI

LOCATION

1000 t

Level Press. Temp ″VAC (°F)

123

CONDENSER Water Temp

Refrigerant

REFRIGERANT

East Wing

In (°F)

Out (°F)

Refrigerant Press. Temp (PSI) (°F)

Water Temp In (°F)

Out (°F)

DATE CLEANED

6-1

158

140

120

125 460

150

105

DHJ

6-2

157

141

119

124 460

150

106 96

DHJ

6-3

158

140

120

125 461

150

107

JMW

TUBES

INITIAL

6-4

160

140

119

124 460

150

105

JMW

6-5

159

141

119

125 461

150

105 96

JMW

6-6

161

139

118

126 461

151

106 95

DHJ

6-7

157

138

119

125 460 16

150

105 96

AJK

6-8

160

140

121

125 459

151

104

DHJ

6-9

159

138

120

125 460

150

106 96

DHJ

DATE OF EDDY CURRENT TEST

Operating & Safety Control Tests

OIL PRESSURE SAFETY CONTROL SETTING

TESTS PERFORMED ANNUALLY

MANUFACTURER

CONDITION

DATE TESTED/INITIALS LOW REFRIGERANT PRESS./ TEMP SAFETY CONTROL SETTING

CONDITION

DATE TESTED/INITIALS LOW CHILLED WATER TEMPERATURE CONTROL SETTING

CONDITION

DATE TESTED/INITIALS FLOW/PRESSURE DIFFERENTIAL CONTROL Chilled Water Condenser Water

CONDITION CONDITION

DATE TESTED/INITIALS For reliable and uninterrupted service, the following maintenance items should be given attention as indicated. COMPRESSOR: The compressor should be disassembled after 40,000 operating hours or 5 years, whichever comes first. Impeller(s) should be examined for rubbing, grooves, and cracks, then cleaned, nondestructively tested, and balanced. Guide vanes, linkage, and bushings should be examined for lost motion, wear, and sticking stems. The main shaft, pinion, and gears should be nondestructively tested.

TUBES: The water side surfaces should be cleaned annually. Eddy current analysis should be performed on condenser tubes within 3 to 5 years of service and on evaporator tubes within 5 to 7 years of service. The detection of any wear, corrosion, or distortion of tubes will determine when subsequent testing of the tubes should be performed.

OIL/REFRIGERANT: Record date and amount when oil or refrigerant is added. Also indicate leak tests, repairs, and adjustments. Oil samples should be taken and tested for physical and chemical properties.

CONTROLS: All safety and operating controls should be tested annually, calibrated to design conditions, and their set points recorded. Defective safety devices and controls should be replaced.

Figure 1-10. Extensive logs of equipment operation information help technicians learn the normal operating characteristics and spot long-term trends.

These monitoring functions are now typically handled by computers that are linked to automatic control centers within the facility or at other locations. As equipment operation conditions change, the computer analyzes the information and warns technicians of possible problems. However, it is still the responsibility of the technicians to be knowledgeable in the correct operation of all equipment. Computerized monitoring systems can and do fail. Technicians must always be able apply their knowledge of the system or equipment in the field and make judgements as to what actions are needed. Maintenance personnel monitor the startup of equipment to ensure that the equipment is correctly calibrated

and operating properly. See Figure 1-11. Periodically, the technician makes adjustments and corrections to the equipment while it is operating. A common task is adjusting the timing of a machine operations. For example, a packaging machine must be in the correct position at the correct time for wrapping product. Timing failures can damage the product and cause severe damage to equipment. Maintenance technicians are an important part of the changeover of equipment to different product lines because most problems occur at this time. For example, if the same wrapping equipment is used for different products, maintenance personnel make adjustments to the equipment operation to suit the different product.

Chapter 1 — Maintenance and Troubleshooting Principles 13

MONITORING STARTUP

Resources and programs are available to help guide the process. For example, NEMA publishes recommendations for establishing a PM system for industrial equipment in NEMA ICS 1.3, Preventive Maintenance of Industrial Control and Systems Equipment. In general, the process involves a few basic steps. ESTABLISHING PM SYSTEMS PM SYSTEM AND PLANT SURVEY DATA DEVELOP MASTER EQUIPMENT LIST DEVELOP PERIODIC WORK ORDERS

Figure 1-11. Maintenance technicians monitor the startup of new or repaired equipment to ensure that it is operating properly.

Automated control systems can activate alarms, such as sounds, indicator lights, or error codes, if problems arise. Experienced operators and maintenance technicians use alarms as a guide when solving operational problems, but they also know to look for unusual causes as well. Equipment operators often work with maintenance technicians who operate or make repairs to the equipment while the operator monitors system operation from a control room or at the equipment location.

PM Systems Modern maintenance operations require more than just basic PM activities designed to prevent major problems. A preventive maintenance (PM) system is a system used to record and organize maintenance information, which is then used to make the decisions required to maintain the facility and equipment. This information includes items such as equipment data, maintenance costs, consumables, time on task, and breakdown resolutions. With a consistent flow of accurate operation information, PM systems can help increase efficiency, reduce costs, and minimize health and safety problems. PM systems can also be used to document compliance with environmental and health and safety regulations. The PM system may include the entire facility or only the departments that are expected to see the greatest benefit from improved maintenance practices. Establishing a PM system requires a significant amount of work and organization. See Figure 1-12.

DEVELOP MAINTENANCE SCHEDULE

EMERGENCY WORK

COMPLETE PM WORK

PERIODIC MAINTENANCE

DEVELOP EQUIPMENT HISTORY

CORRECTIVE WORK

DESIGN/MODIFY/ PURCHASE EQUIPMENT

PROJECT WORK INPUT FROM PERSONNEL

Figure 1-12. Establishing a new PM system involves integrating information from many different sources. The PM system is then continually improved with new information from maintenance operations.

Plant Surveys. A plant survey is the first step in implementing a PM system. A plant survey is a complete inventory and condition assessment of the equipment and structure of a facility. See Figure 1-13. Data from the plant survey is entered into the PM system to create a master file for each piece of equipment. This file lists the manufacturer, vendor, serial and model numbers, other identifying codes, parts suppliers, equipment location, and complete service history. The plant survey is completed by in-house personnel or outside contractors. As part of the plant survey, the equipment is carefully inspected and analyzed. Its condition is noted along with any repairs needed to return the equipment to peak performance. These repairs become the first corrective work orders in the new PM system.

14â&#x20AC;&#x192; INDUSTRIAL MAINTENANCE AND TROUBLESHOOTING

Equipment Documentation. All equipment documentation is gathered while assembling the master equipment files for a plant survey. This includes construction prints, wiring diagrams and schematics, replacement parts data, and installation, operating, maintenance, and troubleshooting manuals. See Figure 1-15. Obtaining copies of applicable codes and standards may also be necessary. System documentation may be a mixture of hardcopy documents or electronic files. Maintenance personnel must be able to locate information quickly in either format. Hardcopy documents require two copies. A reference copy, often the original document, is stored in a secure and permanent location. The working copy is used for daily tasks. The reference copy is used to make a new working copy if the working copy is lost or damaged. Any changes must be noted on both sets of documents. Electronic files are commonly used for storing maintenance information because they are easy to store, organize, and access. Electronic files of large, complicated drawings are sometimes easier to use than traditional hardcopy documents because specific sections can be enlarged on screen to display details. The files are stored on shared computers or networked storage so that they are available to all maintenance personnel. Although electronic files are considered to be the reference copy, some organizations print paper copies to record changes and to use as backups in the event of computer problems.

PLANT SURVEYS EQUIPMENT INFORMATION EQUIPMENT IDENTIFICATION: LOCATION:

4247 Piedmont Building 2, Floor-1 Room 23 CL15F

DATE OF PURCHASE: VENDOR:

Furnace #1 - FUR0001.00

08/17

Lewis Systems, Inc. 1862 Erie St. Cleveland, OH

VENDOR PHONE:

216-555-1340

MANUFACTURER:

Brown Boveri, Inc.

MODEL #:

IT6P

SERIAL #:

OP2810C2B

EQUIPMENT DATA: (List all parts and part numbers important to the operation of the equipment.)

Figure 1-13. A plant survey is used to collect basic information on a piece of equipment.

The plant survey may use paper forms to collect information that is later entered into a computer. This forms the beginning of a master equipment file. See Figure 1-14. Information can also be entered directly into a laptop computer or mobile device and, if needed, transferred to a main computer later.

MASTER EQUIPMENT FILES Description: Asset ID: Asset Type: Parent ID: Priority: Manufacturer: Model: Serial Number: Vendor: Vendor Address: Vendor Phone: Asset Tag: Location: Department ID: Cost Center: Supervisor:

Furnace #1 FUR0001.00 Furnace Systems 8 Active: Brown Boveri, Inc. IT6P OP2810C2B Lewis Systems, Inc. 1862 Erie St. Cleveland, OH 55117 216-555-1340 00509 4247 Piedmont Building 2 Floor-1 Room 23 CL15F Fixed Asset Repair Jones, Fred

Voltage: Amperage: Wattage: Phase: Elec Line: Air Area:

440 600 264000 3 10 COMP 6

Warranty ID: Warranty Date:

IT6P882 02/17

YTD Labor Hr: YTD Downtime:

45.00 22.00

TD Labor Hr: TD Downtime: Counter UOM: Current Counter: Counter Rollover: Meter UOM: Current Meter:

Meter Rollover: Purchase Date: Install Date: Retire Date: Install Cost: Replacement Cost:

1 0 1234550

YTD Labor Cost: YTD Misc Cost: YTD Part Cost: Total:

0 02/17 08/05

TD Labor Cost: TD Misc Cost: TD Part Cost: Total:

740.00 493.00 724.00 1231.22 7701.19 9656.41 9620.60 5631.80 14,942.00 30,194.40

97000 97000

Comment: Manufact. warranty extremely strict. Document all hours worked and parts used. Report Totals: Assets: 1

YTD Labor Hr: 45.00 YTD Downtime: 22.00 TD Labor Hr: 740.00 TD Downtime: 493.00

YTD Labor Cost: 724.00 YTD Misc Cost: 1231.22 YTD Part Cost: 7701.19 Total: 9656.41

TD Labor Cost: 9620.60 TD Misc Cost: 5631.80 TD Part Cost: 14,942.00 Total: 30,194.40

Figure 1-14. Information from the plant survey and other documentation is used to create a master equipment file on each piece of equipment.

Chapter 1 — Maintenance and Troubleshooting Principles

RECOMMENDED MAINTENANCE PROCEDURES

Hermetic Motors Annually: • Take insulation resistance test of stator windings. Values below 50 MΩ at an ambient temperature of 85°F or less may indicate moisture in the winding insulation. • Inspect the contacts in the magnetic motor starter for signs of deterioration. • Check all line and load side terminals for loose connections. • Test control relays for proper timing sequence. • Measure line voltage and current load for proper balance. • Test motors that have been tripped by any protective devices. Do not restart them until the windings have been tested and the motor starter circuits have been examined to determine the reason for tripping. Reciprocating Compressors Annually: • Sample oil for analysis. The results will indicate any need for a special service or maintenance activity. • Check the crankcase heater circuit for operation. • Test the low oil pressure cutoff switch, which should be within the time delay rating and at the pressure differential specified by the compressor manufacturer. Replace it if it fails to function properly.

Figure 1-15. Recommended maintenance procedures can be found in equipment documentation from the manufacturer.

Maintenance personnel perform a variety of PM tasks.

System Implementation. Once all documentation is gathered, the list of PM tasks and their frequency is determined. The first place to look for specific PM task recommendations is in the operation and maintenance manuals for each piece of equipment. For example, motor manufacturer PM requirements may include a three-month lubrication interval using a specific lubricant. See Figure 1-16. Additional PM information can be found in service bulletins, online discussion boards, national codes and standards, and trade magazines.

It is important to review contractual requirements for PM. A manufacturer that provides a warranty with new equipment may specify the maintenance requirements that must be completed to maintain the warranty. Also, some insurance companies specify the minimum maintenance that must be completed on equipment that they insure. Once the recommended PM tasks for a piece of equipment are known, they can be modified to meet plant conditions. For example, if the motor is running in an extremely hot location or is stopped and started frequently, the manufacturer may recommend a different lubricant or more frequent lubrication. The appropriate amount of PM is assigned to each piece of equipment, then the work is scheduled and assigned. Routine lubrication and inspections might be assigned to equipment operators, while work requiring more skill is assigned to qualified maintenance personnel. Efficient scheduling generates an even workload throughout the year and ensures that equipment is ready when needed. As maintenance tasks are performed for each piece of equipment, related information is added to the record for that unit.

16 INDUSTRIAL MAINTENANCE AND TROUBLESHOOTING

OPERATOR’S MANUAL

6.17 DRIVE MOTOR LUBRICATION Induction squirrel cage motors have antifriction ball or roller bearings front and rear. At extended intervals they require lubrication. The periods between greasings of the motor bearings can vary, primarily with the severity of the service conditions under which the motor operates. As a general rule, the following applies: Frequency of Lubrication—Normal Environments Motor Size

Lubrication Interval

25– 40 HP

3 Months (or 1000 hr)

NOTE: For severe duty - Dusty locations - High ambient temperatures Reduce time intervals in preceding table to 1/2 the listed value. Lubrication Procedure

Do not expect grease to appear at the outlet. If it does, discontinue greasing immediately.

CAUTION Overgreasing is a major cause of bearing and motor failure. Ensure dirt and contaminants are not introduced when adding grease.

Run motor for about ten minutes before replacing outlet plug. Certain TEFC motors have a spring relief outlet fitting on the fan end. If the outlet plug is not accessible at surface of hood, it is the spring relief type and need not be removed when greasing.

A major cause of motor bearing failure is overgreasing. The quantity of grease added should be carefully controlled. Small motors must be greased with a lesser amount of grease than large motors.

CAUTION Grease should be added when the motor is stopped and power disconnected. When greasing, stop motor and remove inlet and outlet plugs. Inlet grease gun fittings and springloaded outlets are arranged at each end on the motor housing. Use a hand lever grease gun. Determine the quantity of grease delivered with each stroke of the lever. Add grease in the following quantity: Motor Frame Size

Recommended Motor Greases (or equivalents) Chevron SRI . . . . . . . . . . . . . . . . . . . Standard Oil of California Premium RB . . . . . . . . . . . . . . . . . . . . . . . . Texaco Unirex N2 . . . . . . . . . . . . . . . . . . . . . . . . . . . Exxon Dolium R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Shell Rykon Premium . . . . . . . . . . . . . . . . American Oil

Lubrication Amount in3

256–286

1.0

0.8

324–326

1.5

1.2

CAUTION Never mix greases. Mixing greases can cause motor failure.

Figure 1-16. An operator’s manual typically includes comprehensive maintenance information.

CHECKPOINT

SECTION 1.3

1. What does PM aim to minimize? 2. What are three examples of periodic maintenance tasks? 3. When is the need for corrective work typically discovered?

4. What is project work? 5. Which parts of equipment operation are maintenance technicians often involved in? 6. Why is a PM system valuable? 7. What kind of information is collected in a plant survey? 8. Where can recommendations for PM tasks and their frequency be found?

Chapter 1 — Maintenance and Troubleshooting Principles 17

SECTION 1.4

PREDICTIVE MAINTENANCE

Predictive maintenance (PdM) is the monitoring of equipment operation characteristics to determine the degree of wear in a system, compare them to normal tolerances, and predict potential malfunctions or failures. See Figure 1-17. PdM is a system of looking for symptoms of a problem that has not caused a failure yet but probably will in the future. Certain equipment operating characteristics are periodically measured and analyzed for clues that the equipment is approaching a breakdown. The simplest type of PdM uses manufacturer statistics on the average life span of the equipment. Life span is commonly provided in operating hours under certain operating conditions. Equipment operating time can be documented and components replaced before they reach their expected life span. This usually prevents the complication of replacing the equipment after a failure and when the work must be rushed. Instead, the replacement can be scheduled for the best time within a window of time shortly before the expected end of life.

More sophisticated PdM programs compare other operating characteristics to acceptable ranges. If the measurement exceeds the acceptable tolerance, even if the equipment continues to operate adequately, then corrective work is scheduled to address the problem. See Figure 1-18. The equipment is then closely monitored after the maintenance. If the problem reoccurs, the equipment application and design are analyzed and changes are made as required. Alternatively, the measurements may still be within tolerance, but they may be gradually trending toward the limit. This may trigger either the scheduling of corrective maintenance or further monitoring. For example, temperature is a commonly measured equipment characteristic, particularly for motors. Higher temperatures indicate either excessive resistance in the electrical wiring or excessive friction in the moving parts, such as bearings. Motor temperatures higher than ambient are acceptable to some degree, as specified in manufacturer documentation. However, when temperatures approach or exceed the allowable tolerance, further testing is done to determine the cause of the problem and the next course of action.

PREDICTIVE MAINTENANCE (PdM) METHODOLOGY START COLLECT DATA

YES VALUES WITHIN TOLERANCES?

NO ANALYZE DATA PERFORM MAINTENANCE PROCEDURES

PROBLEM REOCCURS?

YES

DESIGN OK?

CHANGE DESIGN

ANALYZE DESIGN

YES

APPLICATION OK?

CHANGE APPLICATION

ANALYZE APPLICATION

Figure 1-17. PdM uses tests and procedures to anticipate an equipment failure so that it can be prevented. Since it is a significant investment, PdM is most commonly used on expensive or critical equipment.

18â&#x20AC;&#x192; INDUSTRIAL MAINTENANCE AND TROUBLESHOOTING

PdM MONITORING

OPERATING CHARACTERISTIC

CORRECTIVE WORK SCHEDULED

RANGE OF ACCEPTABLE TOLERANCE

OUT OF SERVICE

TRENDING TOWARD OUT-OF-TOLERANCE AGAIN

TIME

Figure 1-18. PdM relies on long-term trends in equipment operating characteristics to anticipate and prevent failures.

In addition to temperature analysis, other common types of PdM programs include vibration analysis, ultrasonic analysis, oil analysis, and electrical analysis. Also, sometimes simple visual and auditory inspection by an experienced technician can be used as a PdM tool. See Figure 1-19. Unusual appearance or sounds of operating equipment may be obvious to trained maintenance personnel and are signs of a problem that is hard to detect by other means. For example, dust collecting in certain spots may indicate air leaking from a duct or moving parts being gradually worn away. VISUAL AND AUDITORY INSPECTION

PdM Program Implementation Implementing a PdM program typically requires a substantial investment in training, equipment, time, and organization. Training involves learning to take measurements or conduct inspections that may be outside of the typical maintenance task skills. Sometimes special equipment is needed, which adds to the expense and increases the training requirement. Fortunately, monitoring equipment, such as thermal imagers and vibration testers, are becoming increasingly user-friendly. It is also necessary to learn how to interpret or analyze the information and determine the most efficient response. Perhaps the largest PdM investment is the time needed for maintenance technicians to periodically check the equipment. This is time not spent performing other maintenance work elsewhere. Equipment must be monitored repeatedly, though it may be done on a random, scheduled, or continuous basis. Random monitoring is unscheduled equipment monitoring as required. This may be done whenever all time-sensitive work is completed and technicians are available for PdM work. It may also be done while a technician is already working on a machine, and it is convenient to add a task. Scheduled monitoring is equipment monitoring at specific time intervals. These PdM tasks may be entered into a PM work order system like other scheduled work. Continuous monitoring is equipment monitoring at all times. This requires sensing devices that are permanently attached to the equipment being monitored. These devices may need to be periodically checked to download or record data, or the devices may automatically transmit data to a central PdM database for analysis. PdM programs may generate large amounts of data quickly, which must be carefully recorded and organized so that it can be analyzed for problems or long-term trends. Computer software is well-suited to record, organize, and analyze PdM data.

PdM Program Disadvantages

Figure 1-19. Even simple visual and auditory inspection by an experienced technician can identify subtle equipment changes that may lead to a problem.

Since a PdM program typically requires substantial investment, it is most commonly used for expensive or critical equipment. A PM program typically covers a large number of machines and equipment, but a PdM program may apply to only a small subset of the equipment. This typically includes equipment that cannot tolerate performance issues or failures and must be maintained to maximize its service life.

Chapter 1 — Maintenance and Troubleshooting Principles 19

Another disadvantage of PdM is that it is not a perfect prediction tool. PdM analysis may indicate that failure is approaching, but it is likely impossible to know the exact timing of the potential breakdown. PdM is a tool used to inform decision making, but a person must balance the risks and costs involved and decide whether to take action. For example, production demands might require risking a breakdown to continue critical operations. Once that critical period is over, and hopefully no failure has occurred, then the equipment can be removed from service and repaired. Alternatively, a PdM program can be overly conservative, and useful service life of the equipment is wasted when it is repaired or replaced too early. The risk of wasting resources to ensure critical equipment is kept operating is part of the indirect costs of a PdM program. CHECKPOINT

SECTION 1.4

1. Why is the word “predictive” used to describe a predictive maintenance program? 2. What type of information does the simplest type of PdM use? 3. What are three characteristics that may be measured as part of a PdM program? 4. What types of equipment monitoring are used to collect data? 5. Why is PdM typically limited to only certain equipment? 6. What is the risk of having an overly conservative PdM program?

SECTION 1.5

MAINTENANCE AND REPAIR MANAGEMENT Unscheduled maintenance, PM, and PdM all include a variety of systems and tasks that help technicians perform work as efficiently, accurately, and cost effectively as possible. This includes systems for documenting work intended and completed, organizing equipment data, managing parts inventory, and analyzing costs. Technicians should utilize the tools that are available to them in order to not only help themselves but to help other technicians who may work on the same equipment

later. For unscheduled maintenance, urgency may dictate some tasks, such as documenting the troubleshooting process, be postponed. However, these tasks should be completed as soon as possible to maintain complete maintenance records.

Work Orders Work orders are used to organize, plan, and monitor scheduled maintenance tasks. A work order is a document that details specific maintenance tasks to be completed. Work orders commonly include time, date, name and location of the equipment, work description, approximate time to complete the work, and safety requirements. See Figure 1-20. Some work orders also list the steps for completing the task. Work order forms may be handwritten, but many facilities use computer systems that can also automatically generate work orders based on maintenance intervals and other information stored in the system database. Work orders are often printed out so that they can be easily brought to the work site for reference. All work orders have a scheduled completion date. Work that cannot be completed by this date is listed in a delinquent work order report until the work is completed. See Figure 1-21.

Work Priority Work priority is the order in which work should be done based on importance. The most important work is done first, followed by less important work. Work priority is indicated on a work order. Though work priority methods vary from plant to plant, a three-level priority method is commonly used. The highest priority is for work relating to safety, downtime, and production efficiency. Emergency or other high-priority work requests are handled as they occur during a shift. The medium priority is for scheduled periodic maintenance. The lowest priority is for long-term projects. Some plants list work priority by completion time, such as “immediately,” “within two weeks,” or “timely.” The size of the plant and the number of available personnel dictate work-priority procedures. For example, some plants list PM tasks as the highest priority with only designated workers responding to emergency calls. Additionally, many maintenance technicians are on call during their lunch and breaks. This allows quick response to high-priority maintenance calls.

20 INDUSTRIAL MAINTENANCE AND TROUBLESHOOTING

WORK ORDERS EQUIPMENT DESCRIPTION

MAINTENANCE TASK

WORK ORDER NUMBER

MAINTENANCE FREQUENCY PREVIOUS MAINTENANCE WORK COMPLETED

MAINTENANCE PROCEDURES

Figure 1-20. A work order documents all the information needed to identify a particular maintenance task.

DELINQUENT WORK ORDER REPORTS DELINQUENT WORK ORDER PACIFIC CIRCUITS — REDMOND, WA Delinquent Work Order Report Date: 10/10

WO No.

EQUIPMENT WORK ORDER NUMBER

LOCATION CRAFT CODE EQUIPMENT NUMBER

Work Order Sequence

Page 1 Meter Days Date Due Over Over Due Due Cal Freq

Equipment Description Location/Craft Code/Equip. No.

Date of Last PM

PM910000

14 DAY PM ON DEM HOT PRESS LAMINATION /009 /3007

3007

10/03 14

09/19

PM910004

30 DAY, ALUMINUM SCRUBBER, LAMINATION /097 /3014

3014

10/03 30

09/03

PM910040

IR FUSER PM - BI MONTHLY PLATING /005 /1017

1017

09/24 15

09/09

PM910041

14 DAY PM, GOLD LINE MP80 PLATING /007 /1007

1007

09/27 14

09/13

PM910042

30 DAY PM, GOLD TIP PLATING PLATING /005 /1007

1007

09/26 30

08/27

DAYS OVERDUE

PM910076

14 DAY LUBE/FILTER CHECK, IS FLUX SCRB. PLATING /005 /1020

09/30 14

09/16

DATE DUE

PM910077

14 DAY HIGH PRESS PUMP PLATING /007 /1020

1020

09/13 14

08/30

PM910022

14 DAY 857 ETCH SYSTEM PLATING /098 /1019

1019

10/09 14

09/25

PM910025

30 DAY PM LAMINATOR, D.F.O.L DRY FILM OUT /002 /8006

8006

10/03 30

09/03

PM910026

90 DAY LDR \UNLDR CLUTCH \BRAKE ADJUSTMENT LAMINATION /009 /3007 5005

77 9

04/26 04/04

PM910141

180 DAY ELEC PM, HERCULES LAM., DRY FILM INN /001 /5005

07/25 90 10/01 180

Figure 1-21. A delinquent work order report lists scheduled work orders that have not been completed.

LAST PM DATE MAINTENANCE FREQUENCY IN DAYS

Chapter 1 — Maintenance and Troubleshooting Principles 21

Logbooks A logbook is a notebook or electronic file that documents maintenance tasks and additional information, if needed. There may be different types of logbooks. Some are assigned according to units of equipment, like those that document operational maintenance monitoring. For example, a particular logbook contains all of the monitoring and maintenance documentation on Oven #3. Logbooks are also used by individual technicians to document the various tasks they complete during a shift. See Figure 1-22. This typically includes several tasks spanning different systems or equipment. Handwritten notes may be used during a shift, but this information is often entered into computer databases later. Some facilities, however, may utilize mobile devices connected to a networked maintenance database for technicians to enter information and look up equipment histories directly. As a technician performs work on a particular piece of equipment, entries may be generated for both

equipment and technician logbooks. A single entry can be assigned to both a technician and a piece of equipment and easily appear in both electronic logbooks. This is one reason that computerized systems are particularly useful. See Figure 1-23. Some maintenance organizations keep additional, specialized logs. For example, a maintenance department complaint log records all complaints regarding conditions in the facility and how each condition was addressed. Logbooks can be extremely useful in troubleshooting. Well-organized and up-to-date maintenance records can provide hints indicating difficult problems. For example, a large air-conditioning chiller requires frequent monitoring and logbook entries. If, during the course of taking readings, a technician notes a sudden rise in bearing temperature, the lubrication system is inspected immediately. If oil flow to the bearings is disrupted, the bearings may fail quickly due to overheating. Such a failure is extremely dangerous and expensive to repair.

TECHNICIAN LOGBOOKS

DATE:

NAME:

TIME

SHIFT:

TASK

COMMENTS

Figure 1-22. Logbooks are used by maintenance technicians to record tasks completed during a shift.

22 INDUSTRIAL MAINTENANCE AND TROUBLESHOOTING

CROSS-REFERENCING LOGBOOKS Pat Williams Activity Log Mar 2

Received parts orders and checked them into inventory. Cleaned and organized parts inventory room.

Mar 3

Oven #2 Maintenance Log Feb 20 Pat Williams

Checked temperatures and operation of Oven #2.

Feb 27 Joe Fisher

Checked temperatures and operation of Oven #2.

Mar 1

Helen Miller

Put Oven #2 off-line for scheduled deep cleaning.

Helen Miller

Returned Oven #2 to service after scheduled deep cleaning.

Pat Williams

Checked temperatures and operation of Oven #2.

Pat Williams

Oven #2 temperature is 10°F low. Troubleshot control board and heating element. Replaced faulty heating element

Helen Miller

Checked temperatures of Oven #2 to ensure problem has been resolved. Return Oven #2 to regularly scheduled inspections.

Lubricated chain drive on Conveyor #1. Inspected belt and rollers of Conveyor #1. Checked temperatures and operation of Oven #1.

Mar 4

Checked temperatures and operation of Oven #2. Oven #2 temperature is 10°F low.

Mar 4

Troubleshot control board and heating element. Replaced faulty heating element. Mar 5

Investigated report of unusual noise from motor of Mixer #2. Arranged with Joe Fisher to put Mixer #2 off-line at end of shift for further troubleshooting.

TECHNICIAN LOGBOOK

Mar 5

EQUIPMENT LOGBOOK ENTRIES APPEAR IN BOTH LOGBOOKS

Figure 1-23. Most maintenance tasks should appear on both the technician’s shift logbook and the operation and maintenance logbook for the equipment being worked on.

Maintenance personnel typically begin each shift by reviewing the logbook entries from previous shifts. Based on information in the log and the quantity and type of work orders issued, the maintenance personnel make a list of all work to be completed. The work is then prioritized. In large facilities, a supervisor schedules daily activities. In smaller shops, maintenance technicians do their own scheduling.

Computerized Maintenance Management Systems Maintenance tasks can be organized with hardcopy systems, but many facilities use computerized maintenance management systems. A computerized maintenance management system (CMMS) is a software package or web-based system that organizes PM information and automatically generates reports, work orders, and other data for implementing and improving future maintenance activities. See Figure 1-24.

CMMS software was the norm until relatively recently, when web-based systems became common. Web-based systems have many advantages. They can be accessed by any Internet-capable device, even when off-site, and do not require local data backup. However, they require reliable Internet access at all times, which may not be feasible in some facilities. Many different CMMSs are available, but they generally provide similar features, including providing quick access to maintenance information, issuing and tracking work orders, determining the costs of maintenance activities, scheduling maintenance work, managing maintenance inventories, and assisting in troubleshooting. CMMSs are used to collect a variety of information from many sources, organize and store this information, and provide data analysis as needed. See Figure 1-25. Many CMMSs include general PM tasks for common types of equipment to use as a starting point for developing a PM program.

Chapter 1 — Maintenance and Troubleshooting Principles 23

COMPUTERIZED MAINTENANCE MANAGEMENT SYSTEMS (CMMSs)

ANALYTICS

PM TASKS

WORK ORDERS

INVENTORY MANAGEMENT eMaint, a Fluke Company

Figure 1-24. A CMMS provides many integrated features that organize, schedule, and record maintenance activities for improved maintenance efficiency.

CMMS INFORMATION MANAGEMENT

ANALYSIS

BOO

LOG

RDE

O ORK PM W

EQUIPMENT INFO

MAINTENANCE WORK

PM RECOMMENDATIONS

TROU

BLES REPO HOOTING RTS TROUBLESHOOTING WORK

Figure 1-25. A CMMS organizes and stores information from a variety of sources and provides reports and analysis of maintenance activities.

24â&#x20AC;&#x192; INDUSTRIAL MAINTENANCE AND TROUBLESHOOTING

CMMSs also help technicians analyze the frequency and type of PM work and make adjustments in order to keep equipment in peak operating condition with minimal cost. Excessive PM work increases maintenance costs, but inadequate PM work also results in high costs due to an increase in breakdowns. Determining the optimal frequency is an ideal task for a computerized system. Data compiled from the PM system is also used for assessing plant performance, equipment service life, energy costs, equipment purchasing needs, insurance costs, and personnel and plant budget decisions.

Some equipment or test instruments are capable of transmitting data directly to mobile devices. See Figure 1-26. As more CMMSs become web-based, their information can be accessed, modified, or added directly from mobile devices. Such easy access helps keep the CMMS database of maintenance data upto-date and supplied with richer information, such as photos, detailed notes, and measurements. DATA COMMUNICATION WITH TEST INSTRUMENTS

Mobile Device Integration Increasingly, information is accessed through mobile devices such as smart phones or tablets. Technicians must be proficient in the use of such devices in the modern workplace. Mobile devices provide communication for maintenance technicians, but with many additional features. They are powerful tools for service and troubleshooting tasks. Except for in high-security locations and other possible restricted situations, mobile devices have become necessary tools for maintenance technicians to have available at all times. The most common mobile device used for service and troubleshooting in the field is a smart phone. A tablet has many of the same functions as a smart phone, but it can display larger images. This is especially useful when accessing or downloading blueprints and technical documents. Phone Communication. A smart phone offers many safety and convenience features for a maintenance technician. For example, a personal phone can be used to contact emergency personnel during a plant fire. The phone is also used to communicate non-emergency information with other facility personnel or with outside suppliers, contractors, or technical help resources. Technicians often form informal networks of trusted individuals to provide mutual help and support. With compatible devices on both ends, video calls are also possible. Data Networking. The data networking capabilities of mobile devices can be used for many other types of communication, such as email, text messaging, web browsing, and in-app communications. Site-specific documentation can be downloaded, saved to a mobile device, and accessed as needed. Equipment manuals, prints, reference tables, charts, and troubleshooting procedures are examples of documentation that could be useful to have on a mobile device.

Fluke Corporation

Figure 1-26. Certain test instruments can communicate directly with mobile devices, making information gathering, analysis, and documenting faster and safer.

Audio Recorders. The audio recorder function of mobile devices can capture voice recordings or equipment noises in a facility. For example, audio notes can be recorded on location for reference later. With the use of a dictation function, information can be transcribed quickly for incorporation into a work order or saving as a text file for follow-up with the customer. Recording specific equipment noise can also be useful when diagnosing a problem. For example, when starting an AC compressor, a recording of the clicking or humming noise emitted can be used when explaining a problem to another technician or the customer. Cameras. The camera on a mobile device can be used in many ways. It can be used to document conditions when first arriving at a piece of equipment or location in the plant. For example, photos of burnt insulation on wires, water on a floor, or corrosion on a valve can

Chapter 1 — Maintenance and Troubleshooting Principles 25

be used as a visual or incorporated into documentation when reporting initial conditions. These recorded images are also invaluable for showing how the problem looked before and after the remedy. A photo of equipment is also extremely useful for reducing downtime when replacing components. The photo of an installation before service begins can be a helpful reference when replacement and reinstallation procedures begin. For example, a picture of a terminal block and wiring connections taken before disassembly indicates where the connections must be when reinstalled. See Figure 1-27. DOCUMENTING CONDITIONS

small text, labels, or switch settings. The camera is also useful for inspecting items in obstructed or tight spaces that cannot be viewed directly. Warning: Always use caution when positioning a mobile device around hazardous moving parts and equipment or exposed energized circuits. Video is useful for visually documenting a problem, particularly ones that are hard to witness in person. For example, if a malfunction is intermittent or can only be initiated from a distant switch, the mobile device can be set up to record video of the problem for later viewing. Third-Party Apps. In addition to the default software, mobile device capabilities can be extended with thirdparty apps. A large and ever-growing selection of apps that could be useful to a maintenance technician, such as a spirit level simulator, a decibel meter, or a personal protective equipment (PPE) selection assistant, are available. See Figure 1-28.

THIRD-PARTY APPS

Figure 1-27. The cameras on mobile devices are useful for documenting field conditions.

Photos also help technicians order replacement parts quickly and efficiently. For example, sending a photo of a motor nameplate to a parts supplier reduces the possibility of error in the description of the replacement motor or parts needed. In addition, showing the installation configuration of a particular component is helpful when specifying parts. For example, a photo of an existing motor/coupling configuration is extremely useful when discussing possible retrofit options with a supplier. A mobile device display can save troubleshooting and repair time as well. For example, enlarging the view of a photo can offer a magnified view of a component. This is especially useful for reading

Figure 1-28. Third-party apps extend the capability of mobile devices by providing industry-specific features.

Some equipment manufacturers provide apps with helpful reference information. Specialized apps may be available that provide maintenance and troubleshooting help for specific types of equipment. For example, apps for managing HVAC system operations may have temperature and pressure charts or superheat/subcooling calculators. The technician inputs the variables and the app completes the calculations. Some equipment may

26â&#x20AC;&#x192; INDUSTRIAL MAINTENANCE AND TROUBLESHOOTING

even have wireless or cable connections for communicating with mobile devices and transferring operational data automatically. Accessories. Common mobile device accessories include a durable case for physical protection and additional batteries to extend the length of time between charging. Special add-on accessories may be available to add new functionality. For example, a thermal imager attachment can be used with a smart phone to allow thermal-imaging capabilities. See Figure 1-29. Another example is a remote body camera that documents tasks and is operated by and communicates through the mobile device. MOBILE DEVICE ACCESSORIES

FLIR Systems, Inc.

Figure 1-29. Mobile device accessories may provide a new hardware-based feature while using the mobile device for power and interface capabilities.

Inventory Management Commonly used consumables and replacement parts must be readily available to maintenance personnel. As parts are used, replacements must be ordered to maintain the inventory. If an essential replacement part is not available, the machine remains inoperative until the part is available. In a perfect inventory control system, there would always be just enough parts to repair the equipment with no unused supplies. Excessive inventory should be avoided because it costs money to purchase, store, and track each part. Also, stocking too many unused parts makes finding necessary parts difficult. Like PM tasks, inventory management involves finding just the right balance between too much and too little.

Small organizations can organize and reorder their parts manually, but inventory management becomes increasingly complex for larger facilities. Inventory management includes the organization and management of commonly used parts, vendor and supplier information, warranty information, and purchasing records. Inventory management is a common part of a CMMS. For example, as parts are noted as replaced in a troubleshooting report, the replacements are automatically removed from the inventory count. Part Numbers. All spare parts should be numbered so their location and quantity can be tracked. Part numbers also associate the part with data such as supplier, equipment use, purchase date, and cost. A part number can be any number that clearly identifies the individual part, such as a manufacturer number, a supplier number, or a unique number specific to the plant. A complete description should be included with the number in the inventory system. Using unique identifying numbers helps prevent confusion when selecting parts. For example, labeling a part as â&#x20AC;&#x153;3 A fuseâ&#x20AC;? does not clearly identify the specific type of fuse. Two 3 A fuses may look alike and be the same size, yet they may have different operating characteristics. For example, a non-time-delay fuse is a fast-acting fuse that provides overcurrent protection. A time-delay fuse is used with equipment like motors that are subject to temporary startup or surge currents. A time-delay fuse may damage equipment requiring a non-time-delay fuse. Likewise, a non-time-delay fuse used in place of a time-delay fuse would cause needless disruption when it blows while a motor starts normally. To expedite data entry and tracking, a part number label is often printed in a computer code that can be read automatically. Barcodes have been used for this purpose for decades because they are inexpensive and reliable. See Figure 1-30. Scanning barcodes as parts are entered and removed from inventory allows the computer to keep up-to-date records of available parts. Inventory Control. When a part is removed from inventory, it should be noted in the inventory record on either a computerized or hardcopy filing system. When the inventory of a certain part reaches a predetermined minimum number, more are ordered. Some computerized systems automatically generate orders that can be faxed or emailed to the supplier. The inventory of each part is typically kept within a minimum and maximum number. Computerized inventory systems can analyze how frequently parts are used so that their minimum and maximum inventories can be adjusted.

Chapter 1 — Maintenance and Troubleshooting Principles 27

BARCODES

Figure 1-30. Barcodes are often used for inventory control, which requires the organization and management of parts commonly used for maintenance tasks.

Some parts are located together in a central storage area and others are kept close to their associated equipment. Each type of part should be stored in separate and clearly labeled boxes. See Figure 1-31. It is the responsibility of maintenance personnel to ensure that the inventory is organized and accurately recorded. When searching for parts, the maintenance personnel should have the old part nearby or have a written copy of the part number to help ensure that the correct part is selected. INVENTORY MANAGEMENT

Figure 1-31. A well-organized parts storage area is important for an efficient maintenance organization.

Ordering Parts. The cost of ordering parts includes both the cost of the parts and the time required for placing the order and sorting the parts when they arrive. Parts are most often ordered over the phone or online. Comparing prices helps locate the best price, and careful ordering saves time and money, which can be critical when a part is needed to repair malfunctioning equipment. When ordering, it is important to note the complete part number. Manufacturer, distributor, and facility part numbers may differ, so it is important to use the correct one. If possible, it may be helpful to have a sample of the part to refer to. Online catalogs may provide detailed specifications and list supplier inventory and shipping, delivery, or pick-up information. The order is logged in a parts order book. When the parts arrive, the order should be checked to ensure that they are as ordered and that the price and quantity are correct. Then, the order is logged as received. If a partial order is received, the items still expected and when they should arrive are noted. A picture of the part needed can be used for reference, if required. Knowledgeable parts suppliers can be of great assistance when encountering problems with locating parts for discontinued or specialized equipment.

Balancing Costs Maintenance personnel must often balance the costs and benefits of maintenance and repairs to equipment. As maintenance and repair information is collected for each piece of equipment, the costs can be analyzed and compared. It usually takes about a year of data to be able to see maintenance trends. Decisions are made based on this information, which is why it is important to keep accurate and thorough records. As time passes and more information is added to the equipment files, costs are continually reviewed and decisions may change. The two common ways in which costs are analyzed to determine the best value for a facility are maintenance versus failure costs and repair versus replacement costs. Maintenance versus Failure Costs. If frequent PM for a certain piece of equipment costs more than the costs of its failure, then it makes sense to reduce PM tasks. See Figure 1-32. Performing excessive PM work drives up the cost of maintenance operations. However, performing too little PM work can result in high failure costs due to downtime, poor productivity, and equipment replacement.

28â&#x20AC;&#x192; INDUSTRIAL MAINTENANCE AND TROUBLESHOOTING

OPTIMIZING LEVELS OF PM Maintenance Costs

Failure Costs

Low

High

Low

Optimal

Consider decreasing PM, which may have little effect on failure costs

High

Consider increasing PM, which may significantly lower failure costs

Reevaluate system/equipment for cost savings; however, high costs may be unavoidable for certain systems

Figure 1-32. A comparison of maintenance costs to failure costs may identify ways to optimize the level of PM.

Determining the optimal amount of PM for each piece of equipment requires a lot of data over a long time. When maintenance personnel have enough data available to review maintenance routines and their actual costs, they may adjust the level of PM. For example, a particular maintenance task interval might be lengthened from quarterly to semiannually. Alternatively, frequent equipment breakdowns drive up failure costs, signaling that the equipment requires more PM. For example, if a recurring problem is found to be caused by lubrication issues, the related components are inspected more frequently. The relatively small increase in maintenance costs is more than offset by significantly reduced production disruptions. Maintenance costs are relatively simple to calculate, though they can include a wide variety of costs. See Figure 1-33. Costs include the maintenance personnel labor and the purchasing of parts and expected consumables, such as fluids, filters, and worn-out components. Consideration should also be given to personnel, facilities, and equipment that support these activities. For example, a large inventory control system improves maintenance efficiency, but it costs money to operate. Similarly, tools and repair equipment are needed by the maintenance personnel to help them do their jobs. These costs and other maintenance support costs are added as overhead, and a small percentage is allocated to each labor hour to estimate the contribution to equipment maintenance costs. As for failure costs, the most direct types are the costs to repair or replace failed equipment. Depending on the type of equipment and its importance to facility operations, multiple indirect costs may also be applicable, and they can be significant. Indirect failure costs

may include equipment downtime, quality disruptions that lead to the production of a substandard product or reduced productivity, legal costs resulting from lawsuits or fines imposed by regulating agencies, and wasteful energy consumption. Only some of these costs can be measured accurately, but estimates of others are still important. Accountants typically assist with these calculations.

BALANCING MAINTENANCE AND FAILURE COSTS

OVERHEAD PARTS/CONSUMABLES LABOR

LEGAL WASTE DOWNTIME REPAIR/REPLACEMENT

MAINTENANCE COSTS

FAILURE COSTS

Figure 1-33. A variety of factors, both direct and indirect, should be accounted for when calculating maintenance and failure costs.

Sometimes both maintenance and failure costs are high and may be unavoidable for certain critical systems, including those related to health or safety issues. However, the maintenance department should always look for ways to reduce these costs, such as through upgrading system controls, installing more modern equipment, or rearranging components to improve access and efficiency. Repair versus Replacement Costs. When equipment fails, the maintenance department may need to choose between repair or replacement. In some cases, the failure is so catastrophic, or the choice to replace is otherwise so obvious, that no further analysis is needed. However, often the decision requires some work to compare the two options.

Chapter 1 — Maintenance and Troubleshooting Principles

The cost of repair parts or replacement equipment is just one portion of the total repair cost. Multiple other factors must be considered. Some possible considerations include the following: • Does the work need to be done on an emergency basis, requiring personnel overtime and expedited shipping? Extra labor and parts acquisition costs could be significant. • Which option will result in a longer downtime for the affected system and possibly other systems? Depending on the circumstances, either repair or replacement may take longer. • How would other systems be affected? For example, physically bringing a large piece of new equipment into the facility could disrupt nearby piping, ductwork, wall openings, or electrical services. • Is the equipment still covered by its warranty? Was it maintained as required by the manufacturer, and what does the warranty cover? The manufacturer may require certain conditions for making repairs to maintain a warranty or as part of the purchase contract. These situations typically involve authorized technicians at either the manufacturer or certified repair agency. If the warranty applies, the repair versus replacement decision is then heavily influenced by the manufacturer. • Can the work be done by the in-house personnel with on-site tools and equipment, or are contractors with specialized equipment needed? In some cases, it is simply less expensive to have work done by outside specialists. For example, in a plant with only a few refrigeration systems, the in-house personnel perform most maintenance. But if a serious problem requires that refrigerant be removed from the system, an outside contractor is called. The cost of refrigerant recovery equipment is too large for this plant given the frequency that the equipment is needed. • Do regulations or insurance stipulations require outside expertise? Insurance companies or regulations may require that certain equipment, such as elevators, boiler safety valves, and gas and electric meters, be serviced by outside personnel with special training. • Would replacement equipment offer other benefits? Perhaps a newer model is more energy efficient, increases production, offers more features, is smaller, requires less maintenance, or otherwise affects future costs. Even if the immediate replacement costs are greater than repair costs, replacement may still be a better long-term decision.

Out-of-Plant Services Outside help is often necessary for advice or work that requires expertise not available from the regular maintenance crew. For example, installing new equipment or making major renovations may require companies with specialized tools and expertise. Also, special projects may require extra personnel on a short-term basis. Outside companies can help perform this work while the regular maintenance crew maintains other plant operations. In addition, outside companies typically provide warranties for their work in case problems occur during the equipment break-in period.

If a maintenance project requires special equipment, the best option may be to hire an outside organization with the necessary skills and equipment to complete the work.

CHECKPOINT

SECTION 1.5

1. What information is typically included on a work order? 2. What is an example hierarchy of work priority? 3. How can logbook information be useful for troubleshooting? 4. What are some advantages of web-based CMMSs? 5. What are some ways that mobile device cameras are particularly useful for maintenance and troubleshooting? 6. How might some equipment communicate with mobile devices directly? 7. What are disadvantages of maintaining a large on-site inventory of replacement parts? 8. Why are part numbers important for managing inventory? 9. What are common considerations when calculating all maintenance costs? 10. How can manufacturer warranties affect repair versus replacement considerations? 11. Why are out-of-plant services sometimes needed?

30 INDUSTRIAL MAINTENANCE AND TROUBLESHOOTING

SECTION 1.6

TROUBLESHOOTING

Troubleshooting is the systematic investigation of the causes of system problems to determine the best solution. The ability to troubleshoot effectively is a skill that combines technical expertise, logical and creative thought processes, and interpersonal skills. This skill improves through experience with troubleshooting and evaluation of the causes of and solutions to problems.

Troubleshooting Methodology Troubleshooting methodically eliminates various system processes and components as causes of a malfunction until the malfunction is located and diagnosed. Maintenance personnel use troubleshooting skills on a regular basis. The troubleshooting process consists of investigating, isolating, remedying, and documenting problems. See Figure 1-34. As always, maintenance personnel must follow all applicable safety procedures while troubleshooting. TROUBLESHOOTING PROCESS Investigate Problem • Gather resources • Question operator • Inspect equipment • Operate equipment (if possible) Isolate Problem • List all symptoms • List all possible causes • Formulate testing sequence • Determine cause of problem Remedy Problem • List possible repairs • Formulate repair plan • Perform repair • Observe operation Document Problem • Document process, remedy, and recommendations Figure 1-34. A troubleshooting checklist guides maintenance personnel through diagnosing and remedying a problem.

Investigating Problems. As problems that require troubleshooting arise, maintenance personnel should prepare as much as possible before working on-site with the affected equipment. Certain actions greatly improve troubleshooting efficiency but may not be possible due

to time constraints and circumstances. These actions include the following: • Review previous work orders, equipment age, and equipment operating history. • Check plant procedures and equipment manual for relevant information. • Determine the effect of the equipment on overall plant production and operation. • Consult with other maintenance personnel who have experience with the equipment. • Gather required tools, test equipment, and safety equipment. When arriving on-site, the first step is to communicate with the equipment operator or personnel familiar with the equipment and gather information about the problem. Communicating with personnel includes determining when the problem started, how the equipment functions normally, if the equipment has a history of problems, and what actions were taken to remedy past problems. It must also be verified that plant procedures were followed in the operation of the equipment and that no unauthorized changes were made. In some cases, equipment displays include fault codes or other error indicators. Technicians access system documentation to understand the meaning of codes. See Figure 1-35. Corrective actions will often be suggested for each code, though it is possible that a different problem is causing the error and complicating the troubleshooting. Technicians should be willing to follow all troubleshooting leads. Wherever possible, equipment is inspected while it is deenergized. Equipment must be carefully inspected for conditions such as leaks, broken parts, or unusual odors. When equipment must be operating as part of the troubleshooting process, all personnel must be safely located and equipment must be protected from further damage as a result of operating the equipment. General start-up testing procedures include the following: • Check fluid levels, guard positions, belt tightness, and loose parts before turning on a machine. • Turn on and test one part of the equipment or system at a time. • Test all manual operations first. • Verify that all safety devices are working properly. • Operate the equipment long enough to obtain normal operating fluid levels, pressures, belt tensions, and temperatures. • List all symptoms of the problem. If similar equipment is available, compare operating characteristics.

Chapter 1 — Maintenance and Troubleshooting Principles 31

FAULT CODES

FAULT CODE NUMBER

F001

Overvoltage

F002

Overcurrent

F003

Overload

F005

Inverter overtemperature (internal PTC)

FAULT CAUSE

CORRECTIVE ACTION(S)

Check whether supply voltage is within the limits indicated on the rating plate. Increase the ramp-down time (P003). Check whether the required braking power is within the specified limits. Check whether the motor power corresponds to the inverter power. Check that the cable length limits have not been exceeded. Check motor lead and motor for short circuits and ground faults. Check whether the motor parameters (P081 – P086) correspond with the motor being set. Check the stator resistance (P089). Increase the ramp-up time (P002). Reduce the boost set in P078 and P079. Check whether the motor is obstructed or overloaded. Check whether the motor is overloaded. Increase the maximum motor frequency if a motor with high slip is used. Check that the ambient temperature is not too high. Check that the air inlet and outlet are not obstructed. Check that the integral fan is working.

Figure 1-35. Some equipment has self-diagnostic features and displays the likely problem as a fault code.

Warning: In many cases, troubleshooting technicians must work on live equipment, such as when taking voltage or current readings, taking pneumatic or hydraulic pressure measurements, or observing the movement of robotic equipment. Extreme caution is required and all mandated safety regulations must be followed, including using PPE and observing the limits of approach for live electrical work as described in NFPA 70E, Standard for Electrical Safety in the Workplace. Isolating Problems. Isolation of a problem begins with listing possible causes. Writing down the symptoms and the likely causes can help focus the process. The simplest, most likely cause is identified and a logical troubleshooting sequence is established to test each suspect part of the equipment. All plausible causes, no matter how simple, should be considered. This may include checking if batteries are charged, tanks contain fuel, or equipment is plugged in. Problems that have occurred in the past with the same or similar equipment should also be considered. Plant procedures and manufacturer troubleshooting procedures, which may be in the form of a list of steps or a flow chart, should be consulted. A list of steps starts with the simplest, most likely cause. See Figure 1-36. The order of steps eliminates the possibility of inadvertently skipping over the cause of the problem.

LIST OF TROUBLESHOOTING STEPS

MIDCO TOOL DESIGN INC. Programmable Controller Troubleshooting & Replacement 1. If there is no indication of power (status lights OFF) on the programmable controller, measure the voltage at the incoming power terminals on the power supply module. 2. If voltage is present and correct, replace power supply on programmable controller. 2.1

Remove power from the programmable controller.

2.2

Disconnect the power lines from the power supply terminals.

2.3

Disconnect the processor power cable from the power supply output terminal.

2.4

Remove the four mounting screws on power supply to free power supply from main panel.

2.5

Grasp the power supply firmly and pull out.

2.6

Press the replacement power supply into the main panel.

2.7

Replace and tighten the four mounting screws.

2.8

Connect the processor power cable.

2.9

Connect the power lines.

2.10 Turn power ON.

Figure 1-36. Troubleshooting procedures detail steps and actions for investigating equipment problems.

32 INDUSTRIAL MAINTENANCE AND TROUBLESHOOTING

When working through troubleshooting steps, the process may be recorded on a testing chart. A testing chart is a record of the tests performed, along with their results, during a troubleshooting process. See Figure 1-37. Troubleshooters must know what to expect as a normal result of each test or inspection. When one component tests as good, the next component in the sequence is tested. The component is inspected or tested further if it is bad. A flow chart is a diagram that shows a logical sequence of troubleshooting steps for a given set of conditions. See Figure 1-38. Flow charts use symbols and interconnecting lines to help a troubleshooter follow a logical path when solving a problem. The flow chart is read by beginning at the start ellipse, following the arrows, and answering yes or no to the questions in the diamonds. The answer determines the path to the next instruction. The flow chart format condenses lengthy word descriptions into an instructional graphic for quick problem solving. When troubleshooting, it is easy to become focused on only one possible cause of a problem. For example, if a maintenance technician is convinced that a particular switch is the problem, other suspect devices may be overlooked. If a dead end is reached, the problem is reevaluated, and the process is started over by listing all possible causes again. When necessary, another maintenance technician is consulted. Maintenance personnel must use all resources available to repair equipment quickly and economically.

It is important to look for potential secondary causes. These are problems that cause the conditions that caused the original problem. If secondary causes are not remedied, the original problem is likely to reoccur. The chain of causes is followed back to the root cause by asking questions. For example, an airconditioner motor stops working and the primary cause of failure is a blown fuse. That is easily fixed, but why did the fuse blow? What caused the high current? Perhaps the motor was overloaded. What could cause the motor overload? A clogged filter may have obstructed the airflow, making the motor work harder. A few other examples to consider include the following: • A component is damaged easily if it is located near moving equipment. The secondary cause is the location. The remedy involves relocating the component, if possible. • A fluid filter is clogged sooner than expected. The secondary cause is the fluid reservoir is left uncapped, allowing dirt to enter easily. A remedy should include ways to ensure that the cap is always replaced after service. • Shelving collapses due to broken supports. The secondary cause is that too much weight was placed on the shelving. Possible remedies include relocating some of the heavy items or redesigning the supports for greater strength.

TESTING CHART 1. Determine possible faulty component(s) or condition(s) to test. 2. Determine test method: visual inspection, manual operation, or voltage, resistance, current reading, etc. 3. Determine expected results if component is good or bad. 4. Perform test and record results.

PROBLEM: LIGHT DOES NOT TURN ON Component/ Condition Tested

Most Likely

Least Likely

Test Method

Expected Results

Test Results

Bulb

Remove and replace

New light turns on if old one was bad

New bulb did not light

Voltage

Take voltage reading at bulb receptacle

Good voltage should be 120 V

No voltage

Circuit breaker

Inspect and reset circuit breaker

Breaker should not be tripped. If it is, reset it and the light should turn on

Breaker tripped

CAUSE Figure 1-37. A testing chart helps organize the troubleshooting process and becomes a record of the troubleshooting strategy that can be analyzed later for improvements.

Chapter 1 — Maintenance and Troubleshooting Principles 33

FLOW CHARTS ELLIPSE INDICATES BEGINNING OR END OF FLOW CHART

START

DIAMOND CONTAINS QUESTION

BATTERY CHARGE LOW?

BATTERY CONNECTIONS CORRODED OR LOOSE?

STARTER SOLENOID FAULTY?

STARTER FAULTY?

NO ARROW INDICATES DIRECTION

YES

RECHARGE/ REPLACE BATTERY

CLEAN/TIGHTEN BATTERY TERMINALS

REPLACE STARTER SOLENOID

REPAIR/ REPLACE STARTER ENGINE TURNS OVER?

RECTANGLE CONTAINS INSTRUCTION

TROUBLESHOOT OTHER ENGINE SYSTEMS

YES END

Figure 1-38. A flow chart provides easy-to-follow steps in a visual format for a complex troubleshooting procedure.

EQUIPMENT LIFE EXPECTANCY BREAK-IN PERIOD

USEFUL LIFE

WEAR-OUT PERIOD

FAILURE RATE

Remedying Problems. After isolating the cause of a problem, all the possible ways to remedy the issue are listed. Determining which remedy is the best choice involves considering plant production, cost, and maintenance budget. Safety, plant policy, and code and legal requirements must also be considered. In some cases, it may be necessary to temporarily repair the problem until there is a better time to formulate a permanent repair. The age of the equipment affects the plan to remedy the problem. Most equipment follows a typical life expectancy curve that includes the break-in period, useful life, and wear-out period. See Figure 1-39. The break-in period is the time just after installation when equipment achieves peak operating performance. If an equipment problem occurs during the break-in period, the cause could be improper installation or operating procedures. The useful life is the period after the break-in period when most equipment operates as designed. PM is performed during the useful life of the equipment. If a problem occurs during the useful life of a machine, repair is typically the most economical choice. The wear-out period is the period after the useful life of equipment when normal failures occur. If the problem occurs during the wear-out period, the equipment may not be worth repairing.

TIME

Figure 1-39. Equipment breakdowns are most common at the beginning and end of the equipment life expectancy. The age of a piece of equipment within its life expectancy affects maintenance decisions.

Test equipment is used to verify that replaced or repaired parts operate properly. The equipment is monitored for proper function after the problem has been remedied. Sufficient time must be allowed for the equipment to reach normal operating levels and load conditions.

34 INDUSTRIAL MAINTENANCE AND TROUBLESHOOTING

If a repair does not fix the original problem, then the troubleshooting process resumes by reevaluating the written lists of symptoms, causes, and troubleshooting testing charts. It may be necessary to restart the process by gathering more information about the equipment. In the meantime, appropriate personnel are notified, and the equipment is locked and tagged out if the equipment should not be operated. Documenting Problems. When a repair is successful and the equipment operation is restored, the troubleshooting process is recorded on a troubleshooting report. A troubleshooting report is a record of a specific problem, along with its symptoms, the possible causes, any tests conducted, and the chosen repair procedures. See Figure 1-40. The spare parts used in the repair are also recorded and replacement parts ordered as needed. If the equipment requires additional work, the appropriate work orders are generated and scheduled. Troubleshooting may identify further maintenance that could be performed to prevent future problems. For example, if an electronic component inside an enclosure fails due to overheating, maintenance personnel may install a cooling fan in the enclosure when replacing the board. To prevent failures in similar enclosures throughout the facility, fan installation or other cooling measures are taken at these locations as well.

Some organizations or individual technicians keep written logbooks on day-to-day tasks that have been completed and troubleshooting that has been conducted.

Previous troubleshooting reports also provide valuable data when troubleshooting a new problem. If the problem reoccurs, or a new problem is related to a previous problem, the information on the previous investigation and remedy is usually very useful. This greatly improves troubleshooting efficiency.

TROUBLESHOOTING REPORTS TROUBLESHOOTING REPORT

10/7

Date

Department

Susan W. Equipment

Conveyor

conveyor stopped operating

Problem Symptoms Cause(s) Repair

Technician

Shipping motor operates, but conveyor not moving

Conveyor drive belt became loose due to drive pulley misalignment

Realigned and tightened drive pulley Checked and reinstalled drive belt to proper tightness Tested drive system under load

Preventive Maintenance Action Check belt tightness weekly Notes

Build additional covers for drive system to keep it cleaner

Figure 1-40. A troubleshooting report is a record to guide other troubleshooters if a similar problem develops. It also provides a learning opportunity for the troubleshooter completing the work.

Chapter 1 — Maintenance and Troubleshooting Principles 35

Troubleshooting is an excellent opportunity to acquire and improve skills. The key is to follow a logical troubleshooting sequence and to think through each step carefully while working on the problem. After the problem has been solved, filling out troubleshooting reports or work-order documentation is an opportunity to evaluate the troubleshooting process. It is recommended that maintenance personnel keep personal logs to record troubleshooting details, such as an evaluation of the troubleshooting actions, what could be done better in the future, and what needs to be learned to troubleshoot more effectively.

Systems Troubleshooting Troubleshooting by testing individual components solves many failures, but some problems, specifically complex problems, are difficult to solve in this way. Individual component testing narrows the focus of a troubleshooter, but complex problems often require a broader view. This is because complex problems may involve the relationships between parts of a large system or in other systems and not in individual components. Troubleshooters must consider the entire system when trying to identify and remedy a problem. Systems thinking is the consideration of an entire system and its interrelationships with other systems while troubleshooting. For example, an intermittent computer printer problem could be related to occasionally high humidity in the air. A faulty flow control valve on the steam nozzles that add moisture to the air causes the occasional increase in humidity. This malfunction is caused by a buildup of scale in the pipe delivering the steam to the air. The scale is a water treatment problem in the boiler system. Focusing on only the printer prevents the troubleshooter from realizing the true cause of the problem. New system problems can also arise when correcting an old problem. For example, when trying to correct a drafty work area, the troubleshooter may reduce airflow to the area. Reducing airflow to one part of a building sends more air to the rest of the building. This could have a negative effect in other parts of the building, possibly creating hot or cold spots in the other areas. To prevent this, the troubleshooter may have to recalibrate the airflow to other parts of the building and possibly reduce the airflow to the entire building. Systems thinking requires knowledge of control loops. Systems may be open-loop or closed-loop systems.

Open-Loop Systems. An open-loop system is a system in which decisions are made based on only the current state of the system and a model of how it should work. Openloop systems are less common than closed-loop systems. A common open-loop control system uses the outside air temperature to determine when to turn the heat on in a building. See Figure 1-41. This is a simple and inexpensive system, but it may not control the temperature inside the building very well. For example, people and equipment are heat sources that add to the indoor air temperature. Also, if it is a sunny day, even if it is cool outside, the sunlight coming through the windows can heat up the indoor spaces. However, because the system in an open loop, it receives no information on what the actual indoor temperature is and it keeps heating, even when it becomes uncomfortably warm inside the building. OPEN-LOOP SYSTEMS

OTHER SOURCES OF HEAT

CONTROLLER DOES NOT KNOW ACTUAL ROOM TEMPERATURES OUTSIDE THERMOSTAT

HEAT REGISTER

HVAC SYSTEM CONTROLLER

HEATING UNIT

Figure 1-41. Open-loop systems may work well in some situations, but they may not respond to changing conditions.

Closed-Loop Systems. A closed-loop system is a system in which the result of an output is fed back into a controller as an input. Most mechanical, electrical, and electronic systems are closed-loop systems. In a closed-loop system, the reactions of the system become feedback that is measured by a sensor and used by the controller to continually adjust the system operation.

36â&#x20AC;&#x192; INDUSTRIAL MAINTENANCE AND TROUBLESHOOTING

For example, in a closed-loop climate control system, the control system may still measure outside air temperature and anticipate the need to activate the heating system, but it also receives actual indoor temperature information. See Figure 1-42. This information is used as another input and the control system modulates the heating output to keep the indoor temperature within a desired range. CLOSED-LOOP SYSTEMS OTHER SOURCES OF HEAT

ROOM THERMOSTAT

CONTROLLER RECEIVES FEEDBACK OUTSIDE THERMOSTAT

HEAT REGISTER

HVAC SYSTEM CONTROLLER

HEATING UNIT

Figure 1-42. Closed-loop systems incorporate feedback from the results into the controllerâ&#x20AC;&#x2122;s decision making. This allows the system to adapt to changing conditions.

Closed-loop systems become more complicated as the number of input measurements and the sensitivity of the controls increase. For example, a basic closedloop system may measure temperature. A more complex system measures and controls both temperature and humidity, because humidity also contributes to human comfort. The system has two measurement components to consider if the room is excessively hot or cold. There is a greater possibility that a fault will develop in two components than in a single component. System Interactions. Systems may also interact with other systems in ways that are not easily understood or documented. For example, if a building temperature is raised, temperature-sensitive equipment may

malfunction and additional static electricity may be generated. The increase in building temperature lowers the relative humidity, enhancing the generation of static electricity that may cause random electronic failures if the static electricity is discharged into electronic components. While the malfunction of temperature-sensitive equipment could be easily traced to the higher temperature, electronics failures would appear to be random and have no obvious cause. Study by an experienced electronics technician would likely be required to identify the cause of the problems. Similarly, if new equipment is added to a facility or factory, the heat load on the building rises, requiring additional cooling capacity in climate-controlled areas. The electrical supply system may be strained by the additional power demand. The harmonics generated by the computers controlling the equipment may also cause severe power-quality problems in the building electrical system. These types of elusive system interactions are further complicated by the likely time delay between the cause and effect. When a problem arises relatively soon after a change, it is much easier to find the connection between them. However, it is common, especially in interactions between systems, for the problem to be noticed only after some time has passed. Troubleshooters typically look for recent causes first, but they must keep a mindset open to possible causes further in the past as well.

Outside Help for Troubleshooting Outside experts, manufacturers, and distributors can be consulted by telephone, by fax, or online for troubleshooting help. Many manufacturers have toll-free numbers that provide access to service personnel. Similarly, many also provide documentation and resources online for diagnosing and remedying problems. Some manufacturer and trade organization websites host messaging forums for technicians to assist each other. However, sometimes these technical support services require fees or are part of a service contract and can be costly. Alternatively, advice is also available through free online resources, though the sources should be evaluated carefully. When contacting outside support services for troubleshooting help, all symptoms should be written down, manuals and other service material should be nearby, and any computers should be ready to use. Mobile phones allow for such calls to be made from the equipment

Chapter 1 — Maintenance and Troubleshooting Principles 37

location. All tools and test equipment should be within reach and ready to use because the service technician may need the results of tests and inspections. In some cases, service technicians can access the equipment’s fault monitoring system using their own computer and run diagnostic tests remotely.

Integration with PM Systems PM and troubleshooting are often considered separate activities. PM is a formal system with records and planned work, while troubleshooting is performed as an as-needed activity. However, troubleshooting activities can generate extremely useful information that can be incorporated into a PM system. This information becomes part of the body of data used to modify the procedures and amount of work required by the PM system.

CHECKPOINT

SECTION 1.6

1. What is the first step in investigating a problem during troubleshooting? 2. What is a flow chart? 3. What typically causes problems during the break-in period of equipment? 4. What is typically included in a troubleshooting report? 5. What is an example of systems thinking? 6. How do closed-loop systems provide better control of equipment? 7. How should a technician prepare for consulting outside troubleshooters for help? 8. How can troubleshooting be used to improve the PM system for a facility?