Hurdles to program adoption
With such high returns, it would seem an easy matter to sell management on the value of establishing a thermography program and either hiring a contractor or purchasing the equipment and providing the training for an in-house initiative. Unfortunately, the initial investment required still raises eyebrows in many front offices.

Granted, the cost of IR thermography equipment can be substantial (sometimes reaching into the tens of thousands of dollars). But, properly used, it becomes almost insignificant in comparison to the potential savings.

Proper usage is the real rub. An effective program requires high-level education and training of the people involved in it. The best thermography technicians understand not only thermography, but also such associated topics as materials science, physics, thermodynamics, mechanics, electrical systems, thermal insulation, HVAC systems and more. Of course, a thorough knowledge of all safety aspects of the equipment and systems involved is paramount.

Data processing also can be a challenge. In the best of circumstances, thermography data can be integrated with CMMS or EAM software, but this is not always possible-or necessary. So long as data can be analyzed in an appropriate database, thermographers can find ways to spot and track trends and learn to predict potential problems.

Building a program
Contrary to what many users might think, buying the equipment should not be the first step in establishing a thermography program. Experts agree that considerable education and training should come first. Only after the appropriate personnel have become knowledgeable and are able to define the program needs should equipment be considered. Other steps advised prior to equipment purchase include:

• Select personnel for the program who will have the time and inclination to understand thermography and how it can be used.
• Define the initial objectives, realizing that the program must be revised and expanded as knowledge and experience grow.
• Establish documentation procedures that will provide for comparisons and trending.
• Meet with potential service and equipment suppliers to evaluate their experience. Obtain their input on your planned program.
• Investigate safety considerations.
• Identify equipment failures in which thermography could have prevented the failure or reduced the consequences. Show how costs could have been reduced or avoided and define dollar amounts.
• Document potential problems in which timely action prevented unexpected failures. Calculate what costs would have resulted if the equipment had failed unexpectedly.
• Inform superiors of the estimated program cost and expected return on investment.

Sustaining the program
As with all other aspects of preventive/ predictive maintenance, a thermography program itself requires maintenance. Experts emphasize that these programs must evolve as knowledge and experience are gained.

Scanning schedules need to be adhered to and then revised as the program evolves. Often, the frequency of scans on specific equipment can be reduced as experience and confidence increase.

New applications should be developed continually. Nearly any facility can identify benefits outside the traditional uses of IR technology. Imaginative applications only can be identified and developed through dedicated efforts to improve and expand the existing program.

Finally, and perhaps most importantly, documentation of the program's benefits and communication of them to higher management should be a high priority. Consistently compile and present cost/benefit analysis reports for management. The goal is to continually demonstrate the value that the program contributes to the company.

Bob Williamson, Contributing Editor

Workplace organization and orderliness,"5S," housekeeping, tardiness, absenteeism, safety, labor shortages, equipment maintenance and reliability… What do these things have in common?

For starters, we have seen significant efforts to improve all of these areas of business for years. Sometimes, the results of these efforts go dormant, plateau or stop altogether. For example, many plants and facilities have had numerous initiatives to "clean up things " and put "things" in their places. And, many times, the results don't last. It's almost like cleaning up the workplace before the important customer or executive team visits. You know the drill-right? Well, I once met a CEO who, after a plant tour, would sit down in the conference room and point to the paint spots (usually yellow, red, and gray) on the soles of his shoes. He was trying to send a message that this type of "cleanup" is unnecessary and a fl agrant waste of time and money-besides, it ruined his shoes. "This place should look like this, or better, all the time!" he would say.

The same could be said of numerous "improvement programs"-they're kicked off with fanfare, lots of support, then go dark due to lack of followthrough or because other initiatives are competing for resources. Attitudes are shaped...

A long list of short-lived improvements shapes the attitudes on the plant-fl oor and tends to infl uence absenteeism and tardiness and, quite often, workplace safety: the poorer the attitudes, the higher the attendance problems and safety incidents. Equipment maintenance often follows the same track as these other "human-induced" workplace problems.

 

Standing by and watching equipment deteriorate to the point of failure in some plants leads to time in the break room for the operators and others. Thus, breakdowns are rewarded! Then, the "maintenance guys" have to work through break times and meals, and sometimes through weekends to get the equipment back up and running, knowing all along that the causes of the problems could have been prevented. Later the plant manager gets upset with maintenance guys being in the break room when it's no longer break time. Attitudes sink to new lows…Why should we care?

All of us have seen high turnover in certain departments in a plant. People just don't want to work there. Thus, they take the first opportunity to bid out, sign a job posting in another area of the plant or just quit and go elsewhere. Hostile working conditions can prevent formation of a stable experienced workforce in these areas and leave inexperienced junior employees struggling to keep things going during their shifts. Attitudes suffer…Why should we care?

The bottom line
I've heard it in too many plants over the past 30+ years: If the company doesn't care, why should we? Improvement initiatives often are stopped dead in their tracks when this kind of attitude prevails in a plant, a department or even in a crew.

"Who" is the "company" anyway and why should we care? Sure, it can be a building, the name on the top of the paycheck, the badge, the owners, the stockholders, the president, the CEO. On the other hand, all too often, the "company" is represented by the beliefs and behaviors of first-line supervisors, mid-level management, plant management groups and their leaders. Attitudes often are shaped by the "perceived company." We also should recognize that the "company" is a business, a financial entity measured by profit and loss, return on investment-a money-making machine in one form or another. Therefore, if the "company" does not make money, it ceases to exist. It's not an early retirement home for the "why-should-we-care club."

Leadership shapes attitudes
I've seen many a successful operation built on a sound foundation of the "can do" attitudes of its staff-from the plant fl oor to CEO. They are great places to work primarily because of those attitudes, not because their facilities are new or that they pay more than others.

These companies also are remarkable for the "respect for people" that is shown throughout their organizations. They also seem to have a prevailing culture that abhors disorder, interruptions, defects and errors. Their workplaces are relatively clean, organized, well-lighted, comfortable and safe. Their equipment is reliable. People work together across departments-shift-to-shift, around the shop fl oor and with the "carpet dwellers" in the front offices.

As a whole, people in these types of successful operations are not afraid to work hard to get the job done right the first time. They also continually seek ways to make their work easier. Attitudes are great! Turnover is almost nonexistent. Absenteeism and tardiness rarely occur.

People really care around these places. If asked why, they would respond: "We ARE the company!" By the same token, union leadership would respond: "If there's no company there's no union!" They know how their job assignment fits into the big picture. They also know, and could show anyone who asks, how their performance would be measured and how that directly supports the key performance indicators of success for the company. These people work together to solve the little problems before they ever became big ones because, according to them, "We ARE the company."

Leadership at all levels in these companies sets the tone of the workplace. Be they first-line supervision, department managers, plant managers or executives, they behave in ways that reinforce the belief that "we're going to win or lose together." These leaders prevent barriers from forming or tear them down when they exist. They have high regard for everyone in their areas of responsibility. The golden rule "Do unto others as you would have them do unto you" is part of everyone's behavior and attitude in these successful operations. Simply stated, this respect for people leads to respectable bottom lines, respectable balance sheets and respectable financial statements.

Cleaning up
You'll read it here and in the pages of other publications time and again. We are most likely in the worst era in U.S. history for attracting qualified maintenance workers. Manufacturers have been on a quest for more than a decade to get more young people interested in careers in manufacturing. But, a big part of our competitiveness struggle is built on a foundation that was set in place over 50 years ago. Unfortunately the nature of this struggle (and its associated body counts) have only been accentuated in recent weeks: Industrial jobs are nasty and plant closings lead to massive layoffs.

There is a continuing short supply of maintenance workers for many reasons, including those discussed in this article. Consider one more reason: chaotic "why-should-we-care" work environments. If "truth in help-wanted advertising" were being practiced, many want ads would look something like the following:

It's clear that we must find ways to clean up our image and promote it aggressively.

If we DON'T care, how can our companies or our businesses be successful? How can we compete against off-shore, low-wage, low-productivity countries?

If we DON'T care, how can we attract the best and the brightest to our plants and facilities?

If we DON'T care, how can our communities benefit from wages, tax base and community service work provided by successful companies and businesses?

Successful, sustainable operations are built around people at all levels of the organization who truly care. We all should care. It's contagious. If we don't, it shows. Sadly, that's contagious too!

bwilliamson@atpnetwork.com

Bob Williamson, Contributing Editor

Peter Zornio, Chief Strategic Officer, Emerson Process Management

It's important to differentiate between this new wireless capability and the way many companies have previously used wireless. Field workers have had remote access to corporate information such as computerized maintenance management systems, and vendor-specific wireless vibration monitoring has been available for 10 to 15 years. But, the standardsbased field wireless technology emerging today is an entirely different animal.

In the past, a plant could use a wireless sensor to monitor device vibration, but that capability couldn't be extended to other plant devices. It was device and vendor specific. This proprietary point-based wireless use in a plant would be analogous to the need for a different power source to run each electrical appliance within a home.

The new wireless infrastructure will allow the installation of sensors virtually throughout the plant on a broad range of devices produced by multiple vendors. Many assets that previously weren't touched by a data-retrieval network, including critical rotating equipment, can now be tapped for data. A user can start with a vibration transmitter, add a few pressure transmitters, then add temperature transmitters and continue to grow their network as new sensor types become available in the future.

Because installation costs are as much as 90% less with wireless, plant assets that once were prohibitive to monitor now can be outfitted to return real-time data, helping managers improve reliability-driven maintenance, production processes and overall asset management.

Some companies may be hesitant to try out this new infrastructure because of previous problems with wireless. These issues have been largely resolved. This new standards-based technology is easy to use, requires low power (battery life of 5 to 15 years), offers industrial-grade security and is reliable (greater than 99%). In addition, the cost to start with wireless on a small scale is nominal and fits easily within a standard maintenance budget.

The low installation cost of wireless makes it tempting for a company to get its feet wet. What's more attractive, however, is the bigger cost savings that will come over the life of the plant through improved predictive maintenance and better operational performance.

To take full advantage of these benefits, companies should view asset management as multiple components-not only the sensors and the network, but the applications and services to support them.

Plants may need assistance identifying business practices that should be changed to fully utilize wireless capabilities and to cope with pressing issues such as an aging workforce. For instance, once wireless monitoring points are added to devices, some operator rounds actually can be eliminated, reducing costs and yielding more consistent, higher quality data. A partner that is an expert in the field can help companies realize the full potential of this new technology and excel at asset optimization.

The application in question involved placing batches of small metal parts to be painted into stainless steel baskets, then cycling them through a series of operations during the painting process. The baskets were suspended from an overhead conveyor by supporting rods connected to stub axles protruding from the sides of each basket. Metal parts were first dipped into a caustic cleaning and de-greasing solvent, treated with a primer, then immersed into an Ecoat paint tank. Painted parts were then cured as they traveled through a 350 F oven.

Because these fully-loaded baskets weighing over 100 lbs. were required to tumble during part of the operation, each would be driven by a sprocket and heavy-duty chain to achieve the necessary rotation (see diagram). Since paint would be applied electrostatically, the baskets were charged with 360 volts DC of electricity supplied from an overhead power source and transmitted to the baskets and parts via the chain/ sprocket/axle assembly.

An arcing problem
Soon after starting up the new painting line, the plant’s production manager discovered a problem. The combination of high voltage coupled with a weak point of contact along the transmission circuit—specifically the axle to basket housing—was causing arcing and sparking problems. The situation was so extreme that it was actually pitting and melting metal components. Entire sections of chain, for example, were being “eaten away” by the electrical charges!

To the rescue
John Graff, engineering representative with Graphite Metallizing Corporation, was invited in to review the application. Established in 1913, this company produces GRAPHALLOY, a graphite-metal alloy used in the manufacture of bushings, bearings and discrete components for machinery and process systems.

Graff knew that the high temperature and corrosive environment were key problems, but that any solution would have to eliminate the arcing on the chain. In light of GRAPHALLOY’s electrical-conducting capabilities, he recommended an iron GRAPHALLOY bearing in a cast iron flanged housing, the combination of which would provide an effective path for the current flow.

The flanged units solved the “triple threat” problem. The path of electrical transmission was controlled and the arcing problem was eliminated. The bushings also survive caustic solvents and the application’s high heat environment. Furthermore, they’re maintenance-free. That’s because the chemical and mechanical properties of these components are so unique that they never need lubrication and perform exceptionally well in applications where other bearings would easily fail.

Graphite Metallizing Corporation
Yonkers, NY

In poorly performing plants, it is typical for Operations, Maintenance and Engineering organizations to work in silos without much cooperation. The traditional view in these plants is that the Maintenance organization delivers service to its customer-which is Operations. The Engineering organization is called "the black hole," where requests for drawing and other documentation updates disappear, and input on design by Maintenance and Production is not included when new equipment is specified and procured. This traditional view doesn't make much sense, as the results of maintenance work are not service. Services are the resources the organization uses to deliver equipment reliability and asset preservation.

One common observation in best manufacturing organizations is that Operations, Maintenance and Engineering work in a close partnership. They view reliable production as their common goal.

The Maintenance organization delivers equipment reliability; the Operations organization delivers process reliability; the Engineering organization designs and procures equipment based on lowest Life-Cycle Cost (LCC) instead of lowest purchase price. As noted in Fig. 1, effective Life-Cycle Costing is an outcome of reliability-driven partnership work systems. LCC considers total cost of ownership for acquisition, installation, operations and maintenance, energy, scrapping, etc. Reliability and maintainability requirements are included in early Engineering specifications with involvement from both Operations and Maintenance organizations.

Harvesting the benefits
Many organizations agree on the principles of a partnership work system-but seldom implement the changes aggressively enough to harvest the benefits. Most of these organizations are under the illusion that they already work in partnership, therefore they do nothing with respect to true implementation. Today, though, plants simply can't afford not to implement a partnership work system. The potential savings are too big to be ignored. Yet, the decision to implement a partnership work system frequently must come from the site-manager level or above. The rest of the organization often is gridlocked and protective of their old roles.

Table I summarizes some maintenancerelated differences between traditional servicefocused organizations and those based on a partnership work system driven by reliability performance.

Moving from gridlock into a position that allows an operation to harvest the many benefits of a partnership work system requires several things.

Implementation…
First of all, your plant manager must believe that implementing partnership work practices is the right thing to do, because it improves the plant's competitiveness and because the plant can't afford not to do it. It is imperative to understand that the shift to partnership practices is not a revolution, but rather more of an evolution through implementation of a lot of common sense. As such, it does not need to take a long time or cost a lot of capital dollars.

Recommended implementation steps…
If much of what you have read in this article makes sense, you now need to sell these ideas to key people in your organization. You often can speed up this process by assembling Operations, Maintenance and Engineering to present and discuss these ideas. Because the principles are based on common sense, there is a very good chance that acceptance will be very high.

Mission statement…
It will help you to first agree on a joint mission statement between Operations and Maintenance for your Production organization. Key Operations and Maintenance leaders must develop this statement together. Start by listing some key terms that should be included in the statement (e.g. Reliable Production, Safety, Partnership). Split into a small groups to work out the wording. Review the statements you come up with several times and you will most probably come up with a mission statement you all agree to. An example could be:

"In a partnership between Operations and Maintenance, we shall safely deliver continuously improved production reliability through long-term implementation of best practices."

Belief: Improved production reliability will decrease manufacturing costs.

The mission statements for Maintenance and Operations must be tied with the foregoing statement. For the Maintenance organization the mission statement could say:

"As an equal partner with Operations, we shall safely deliver continuously improved equipment reliability through long-term implementation of best practices."

Belief: Improved equipment reliability will decrease maintenance costs.

The application and true use of the previous statement will drive very different work practices than if were to be worded like that of the following statement from an actual Maintenance organization:

"As a service organization to Production, we will safely provide effective services at lowest cost."

You would be right in guessing that this organization became extremely cost-driven. The Maintenance manager focused on cutting the cost of his function year after year. He did exactly what was asked by his manager, and followed the mission statement-to the letter. The easiest way to cut maintenance costs was to defer maintenance work and that was what he did. After two years, however, maintenance costs began to rise drastically and reliability decreased. In the end, this Maintenance manager was fired.

What good looks like
What does your organization look like? You might want to conduct a structured educational evaluation of your maintenance performance in order to increase awareness and let your organization discover the gap between best practices and your actual practices. This evaluation should describe your new work practices in such a way that improvements, or the lack thereof, can be measured.

As for what "good" really looks like, refer to Fig. 2.

Christer Idhammar is president and CEO of IDCON, Inc., an international reliability and maintenance consulting group, based in Raleigh, NC, since 1985, and Sweden since 1972. This article, similar to one that first appeared in Paper Age Magazine, is the subject of Idhammar's presentation at MARTS 2007 in Rosemont, IL. For more information, e-mail: info@idcon.com attn.

From asset management and predictive maintenance to security and equipment assessments, companies are increasingly leveraging the benefi ts of wireless technologies and sensors to automate their controls, processes and costs.

According to a recent report from the ARC Advisory Group, the market for industrial wireless devices will exceed 150 million units and over $1 billion annually in just the next few years. These new systems bode well for manufacturers constantly striving to fi nd better ways to manage their operations. The benefi ts and business value are well documented. For example:

• At a large chemical company on the Gulf Coast, a detailed “point solution” analysis of existing wireless systems was conducted to synchronize specifi c applications with overall business objectives. An overarching roadmap and system management control solution was engineered and put into place. Today, this chemical company has a fl exible and secure system that can accommodate new features while realizing immediate benefi ts, such as using sensors to monitor equipment deterioration in real-time for maintenance or replacement—rather than when it breaks and causes much more costly downtime.
• At a major process manufacturing facility, asset management and monitoring of the condition of steam pipes was a high priority. Called “pre-emptive maintenance,” an integrated, facility-wide solution involving sensors was developed to determine precisely when these pipes and related assets needed attention. The same facility also is using high-speed wireless to enhance physical security with additional surveillance cameras around the perimeter and in security vehicles.
• In another manufacturing environment, wireless networks are providing worker mobility for IT, process and maintenance applications, allowing engineers and technicians to perform their jobs in-fi eld where they actually do the work instead of waiting until they get back to their desks or consoles. These improvements in effi ciency are directly tied to increased worker productivity.

Wading through the bramble
The examples and benefi ts of wireless systems continue to proliferate throughout the industrial arena, especially in process control environments. Innovative manufacturers have been discovering a wealth of new applications and benefi ts within plants and across their distributed enterprises. Convenience, low costs and real-time visibility are just some of the reasons behind the growing use of wireless systems, particularly in the oil and gas, power generation and chemical industries. End users, however, realizing the successes of these systems, now are being confronted with a new problem: How do you sort out and manage the growing tangle of disparate solutions that operate on different frequencies, confl icting standards and protocols for different applications?

Zigbee, Wi-Fi, Wi-Max, RFID, VoIP, Bluetooth, Mesh Networks—each is leveraged for specifi c applications. The bramble can be daunting, especially for industrial operations where ad hoc applications are deployed without the expertise of dedicated staff assigned to look at “the big picture.”

For example, some of the emerging challenges accompanying the growth of wireless systems include limited spectrum allocations for certain radio frequencies, a confusion of what standards to follow, interfering and confl icting frequencies, different wireless protocols, different processes and different gateways linking wireless and wired software communication systems.

The consequences of these challenges are especially acute when one department implements a wireless system from a particular vendor and another department does the same from a different vendor. While this evolves in various departments and company locations, a host of issues may arise, such as security vulnerabilities, increased interference in the gateway links, interruption of transmissions, availability problems, data loss and performance degradation. There also may be failures to deliver time-sensitive data when different wireless systems are competing for the same fi nite spectrum.

Maximizing the value of wireless
To maximize the full value of multiple wireless systems, companies today need an overarching, enterprise-wide platform to manage and optimize their multiple wireless systems. Instead of ad hoc implementations and “point solutions,” users need to take the “big picture” approach that analyzes specifi c best wireless applications, then tie them together on a common software platform that’s aligned with overall business objectives.

Think of this platform as a musical score that a symphony conductor follows to ensure that each note from each instrument is harmonized into the overall musical theme. Instead of a cacophony of noise, you get music with harmony and themes working together toward the same objective. How does this work in the real world of wireless technology and manufacturing?

The same general principles of wired network systems management also apply to wireless networks, but since the radio spectrum is fi nite and most wireless devices operate in unlicensed frequencies there are new and unique challenges. As with wired networks, it is essential now to apply enterpriselevel management practices for the operation of wireless networks. In order for these wireless systems to truly improve productivity, security and effi ciency while reducing costs, successful managers must, at least, address the following elements:

• Manage and scale the system architecture.
• Prioritize the business value at the enterprise level.
• Integrate security measures and policies system-wide.

Manage and scale the system architecture…
Optimum execution of any enterprise-wide policy requires a communications architecture that can accommodate the technology of the best categorical network technologies and vendors, emerging standards and best wireless integration practices. The architecture must be based on a well-developed security model that includes functions such as authentication and role-based access control.

Eventually, your network management center should treat your wireless systems the same way it would any other network, by focusing on managing enterprise-wide communications—not the individual technology. Because there will never be a single wireless protocol and frequency, and therefore, because the appropriate technology must be matched with the right application, the best approach for system-wide growth is to have an integrated, yet fl exible, management strategy that can deliver immediate benefi ts. But, it also must be “future proofed” to adapt to business changes and technology developments.

Few companies have the resources to maintain the staff necessary to manage a complete wireless infrastructure, especially since demand for specialists with relevant skills is very high and supply is limited. As a result, outsourcing to one of the emerging specialist fi rms currently may be the most cost-effective strategy to maximize benefi ts and minimize risks.

Prioritize the business value at the enterprise level…
Like wired networks, wireless ones link and deliver data between different points. However, the potential for far more granular data and detailed measurements in areas such as “process variables” exist with wireless because these networks have the advantage of more cost-effective implementation and none of the cost of running wires between multiple points. As a result, it is possible to set up measures for virtually any point or process of the enterprise and receive this information in real time.

Each department undoubtedly can make a strong case for deploying wireless networks within its internal operations, but issues of scalability, security and investment protection make it imperative that these decisions be coordinated at the enterprise level, where priorities such as process controls, security or logistics needs can best be evaluated and executed.

For example, a company competing in a mature marketplace on a strategy of being the low-cost provider might deploy wireless vibration sensors that tell when any asset is not operating optimally—and see maintenance savings show up immediately in the bottom-line. In contrast, a company competing on fast, reliable delivery might fi nd that the added cost of an RFID product tracking system would improve its competitive position.

Implement security measures and policies system-wide…
Sloppy networking practices, rather than intentional malicious interference, are the greatest threats to wireless security. These can include seemingly innocuous practices such as not changing passwords according to policy, using obvious passwords such as initials, adding or deleting devices improperly and any number of other lapses. Interferences also can come from environmental or accidental RF noise, broken RF equipment, dynamic changes in the characterization of the RF site, and the range on non-compatible RF devices generally available. Prevention of these types of problems must be engineered into the network from its inception, and must be covered by an enterprise-aware security and performance management model.

Consider the following situation. One network user might be taking wireless process measurements from a temperature transmitter while another person in the same plant might be running a wireless video camera for perimeter security. A third person might be running an RFID inventory tracking application. Because these three users are in different departments and locations, doing different things on different protocols, each might think he/she is isolated. In reality, though, their radio waves are co-mingling, creating tremendous potential for performance problems and mismanagement. This also highlights some of the issues that arise when trying to consolidate all applications around a single wireless technology, rather than taking the systematic approach of creating a wireless infrastructure.

System-wide management policies must defi ne all methods for using, sharing and securing the available bandwidth. This has implications for planning, implementation, operations, maintenance and expansion. For these reasons, building an effective wireless infrastructure requires an open framework and engineered solution, but just the opposite seems to be happening today.

 

Before any company investigates electrical predictive maintenance (PdM) instrumentation, it should know the strengths of its equipment's insulation, the voltages its motors are exposed to daily, how a motor typically fails and where these faults typically exist. Only then can you really make a decision as to which electrical PdM equipment is the most appropriate for your operations.

How a motor typically fails
The motor stator has two main insulating systems that include the ground wall and turn-to-turn insulation. When this insulation is in a good condition it can withstand the normal day-to-day voltage spikes that exist during starting and stopping. Over time, this insulation will deteriorate as a result of mechanical movement of the windings, torque transients, heat, contamination, and other environmental contaminates. Once the dielectric strength of this insulation falls below the incoming voltage spikes, another failure mechanism is introduced: ozone.

Ozone is a very corrosive gas that will quickly deteriorate insulation. Although the motor will continue to run when this failure mechanism is introduced, as it sees continual voltage spikes, the deterioration rate will accelerate. Eventually, the dielectric strength of the insulation will fall below operating voltage or deteriorate to the point that copper wire will touch turn-to-turn. At this point a turn-to-turn or hard welded short has developed.

According to "Transient Model for Induction Machines with Stator Winding Turn Faults" written for IEEE by Rangarajan M. Tallam, Tom G. Habetler and Ronald G. Harley, when a hard welded turn-to-turn short develops, the shorted windings will develop high circulating currents. These currents, which can be in the order of 16–20 times full-load amps, create excessive heat that the insulation cannot withstand. This intense amount of heat will burn quickly through the insulation-causing motor failure within minutes.

A study performed at Oregon State University, by Dr. Ernesto Wiedenbrug, looked at a motor specially designed with a turn-to-turn fault by installing two wires connected to turn one and turn two of the same phase. These wires were then brought out to a switch. The motor was placed on a dynamometer and run at about 80% load. When the turn-to-turn short was engaged through the switch, the motor began visibly smoking within 45 seconds. While most motors will not run for long with a turn-to-turn short, some exceptions do exist. A motor with a high resistance or floating ground will run with a shorted phase, but once a second phase shorts, the motor will fail catastrophically.

Recommended tests The tests listed on the next page are recommended in off-line field testing:

• Kelvin Method Winding
• Meg-Ohm
• Polarization Index (PI)
• Step-Voltage
• Surge

Each of these test methods evaluates a different section of the motor. Brief descriptions of the first three tests are given in order to offer a complete array of testing information. The nature of high-voltage testing and the necessity of the Step-Voltage and Surge methods, however, remain the main focus of this article.

Kelvin Method Winding...
The Kelvin Method Winding test measures the resistance of the copper wire of the motor circuit. If tested in a PdM application, the test is typically performed from the Motor Control Center (MCC). This test finds issues with miss connections, shorts, opens, unbalanced turn count in one phase to another and different size diameter copper in one phase to another. This test is very valuable and should be performed for predictive maintenance, troubleshooting and quality assurance.

Meg-Ohm Test...
The Meg-Ohm Test applies a DC potential (typically operating voltage) to the windings while holding the case to ground. Table I shows the recommended test voltages for different voltage class motors. Meg-Ohm testing is typically utilized to find grounded motors. It also is a very valuable PdM tool for finding wet and dirty motors. It's not typically used for quality assurance because of the low voltage level at which the test is performed.

Polarization Index (PI) Test...
This test is much like the Meg-Ohm Test, but it is performed for 10 minutes. Over this time period, the molecules in the slot liner paper polarize. When the molecules polarize, the insulation resistance values should increase over the10- minute period. If the resistance increases during this time, it's an indication of good ground wall insulation with no moisture or contamination.

Insulation testing
Until now we have only discussed the low-voltage tests. Upon successfully completing these tests the following is known: the winding resistance is balanced. That means the motor has no shorts, opens or miss connections and the Meg-Ohm and PI indicate that the motor is both clean and dry. These tests, however, still have not confirmed that the motor is capable of starting or running for any length of time. The main reason for performing predictive maintenance on a motor is to learn if it will continue to provide uninterrupted service. Because low-voltage testing is not performed at the voltage a motor typically sees, it can't provide this information.

Many articles have discussed the voltage spikes motors see during starting and stopping. As stated in "Turn Insulation Capability of Large AC Motors, Part I – Surge Monitoring," by B.K. Gupta, B.A. Lloyd, G.C. Stone, and S.R Campbell (IEEE Transactions on Energy Conversion, Vol. EC-2, No. 4, December 1987), these voltage spikes can be in the order of 5 PU (Per Unit):

Calculating this formula for a 480V three phase motor, the PU would be 391.9 volts, or approximately 1960 volts on startup. Logically, if the motor is tested to only operating voltage or below the operating voltage, the user can not be sure if the spikes have caused damage to the motor's insulation that will interrupt service. The other issue is that the turn-to-turn insulation has not been evaluated. In addition, the Meg-Ohm and PI do not evaluate the ground wall insulation for strength or the ability to withstand the high voltages it sees during daily operation. The winding resistance test is only evaluating the motor circuit and not the insulation.

The most effective way to ensure the motor will start and continue to provide reliable service is to test it at the voltages the motor sees during normal operation-which includes starting and stopping. This is accomplished with two tests: Step-Voltage and Surge. These methods evaluate the ground wall and turn-to-turn insulation respectively.

Step-Voltage Test
This DC Test is performed to a voltage that a motor typically sees during starting and stopping. The test voltages, governed by IEEE, are reflected in Table II.

The DC voltage is applied to all three phases of the winding and raised slowly to a preprogrammed voltage step level and held for a predetermined time period. It is then raised to the next voltage step and held for the appropriate time period. This process continues until the target test voltage is reached. Typical steps for a 4160V motor are 1000-volt increments, holding at minute intervals. For motors less than 4160V, the step voltages should be 500 volts (see Fig. 1).

Data is logged at the end of each step. This is to ensure the capacitive charge and polarization current is removed and that only real leakage current remains, thus providing a true indication of the ground wall insulation condition. If, at this point, the leakage current (IμA) doubles, insulation weaknesses are indicated and the test should be stopped. If the leakage current (IμA) rises consistently less than double, the motor insulation is in good standing.

The Step-Voltage Test is necessary to ensure that the ground wall insulation and cable can withstand the normal day-to-day voltage spikes the motor typically sees during operation. If a DC Step-Voltage Test is not performed, the operator cannot be assured that the motor will start and operate without failing in service.

Surge Test
The Surge Test is highly important. That's because 80% of all electrical failures in the stator begin at weak insulation turn-to-turn. These types of catastrophic failures are why NFPA 70 B recommends that Surge and HiPot testing be performed. Regardless of an individual's personal view of Surge testing, knowing that a motor's turn-to-turn insulation is sound is crucial for safety and motor reliability.

During a Surge Test, the equipment will charge up a capacitor inside the unit and dissipate it into one phase while holding the other two phases to ground. Then, automatically, the test unit will slowly increase the voltage from 0 volts to the target test voltage. This generates a waveform, in a shape based upon the inductance of the coil that is displayed on the test equipment screen. If the target test voltage is attained without any frequency change in the waveform, the turn-to-turn insulation integrity has been realized. Fig. 2 is a graphical representation of the waveform at one-third, two-thirds and full voltage of one phase. This is what a waveform will look like when the insulation is in a good condition.

If, at any time, the test equipment sees weak insulation between the turns, the waveform will shift to the left as shown in Fig. 3. The white line on the graph shows the failed waveform at about 1000 volts.

Surge testing theory
When the capacitor is discharged into the winding, it is performed at a very fast rise time (.1 micro second). This produces a nonlinear voltage drop across the turns, producing a potential difference between the turns in succession. As the rise time slows, the operator will notice that the voltage potential difference between the turns is dramatically reduced. This is in contrast to any other signal utilized to diagnose motor issues. No DC test (or AC tests such as an inductance, capacitance, impedance, phase angle or HiPot) will produce this potential difference between the turns.

Physics provides us with Paschen's Law, which states that two bare wires placed next to one another just a thickness of a hair away need a minimum of 325 volts to jump the air gap between the two conductors. These two concepts are the core reason why Surge testing is the natural choice for testing turn-to-turn insulation. The main reason is that if the test equipment doesn't produce a potential difference between the turns above Paschen's Law, the current cannot flow through the fault. If current can't flow through the fault, it will continue through all the coils and not show a difference.

When Surge Testing a coil with weak insulation turn-to-turn, the voltage applied can jump across the weak insulation. Removing these bypassed turns from the circuit reduces the inductance of the circuit and causes the waveform frequency to ring faster. This will produce the frequency shift to the left in the waveform. Fortunately, advancements in technology have led to refinements in the analysis of waveforms, to the point that some test units automatically recognize failures (see sidebar).

Surge comparison In the past the Surge Test has been called a "Surge Comparison Test." Although some individuals believe the Surge Test still needs to be performed in this manner, it really depends on what is being analyzed.

For finding weak insulation, surge comparison is not necessary. As previously noted, weak insulation is diagnosed by a frequency shift to the left and is compared to successive waveforms within one phase. If, however, the following list reflects problems you're seeking to uncover and eliminate, a comparison of each phase is recommended.

• Shorts
• Opens
• Different size diameter copper between phases
• Unbalanced turn count between phases
• Reversed coils
• Shorted laminations

Here again, as referenced in the accompanying sidebar, instrumentation that automatically detects these problems is now available.

Older vs. newer equipment
Just like computers, high-voltage test equipment has changed vastly over the past 20 years.

Today's equipment incorporates modern, high-speed electronic evaluation of changes to resistance, leakage current, leakage current versus time, voltage, step-voltage, dielectricabsorption, frequency response, wave shape, corona inception voltage (C.I.V.) and more to detect faults at or under the levels of energy exposed to the motor during operation. Microprocessor- controlled instantaneous trips allow winding conditions to be evaluated without compromising dielectric integrity. Moreover, the addition of field-developed PASS/FAIL test criteria now makes this testing extremely repeatable.

One of the greatest advances in high-voltage testing has come from via solid-state, highvoltage power supplies replacing the heavy step-up transformer. This has resulted in big improvements to equipment portability. Every test is now digitized and compared to the previously applied pulse. If any weakness is detected, the test is instantaneously stopped, preserving dielectric. The level of weakness is stored for future reference, in the memory bank.

What to look for
When evaluating electrical PdM equipment, keep in mind that every manufacturer is slightly different. Test units, though, should be able to perform the following safety checks to ensure that your motors aren't damaged during testing:

1. Acceptable Meg-Ohm readings should be obtained.
2. Acceptable PI Test should be performed.
3. The test unit should evaluate the Meg-Ohm readings at the end of each step. If the motor does not meet the criteria the test set should automatically stop the test.
4. Current leakage should be monitored continuously and the unit should automatically stop the test if an over current leakage condition exists. Typical over current trip settings are 1, 10, 100 and 1000 micro amps of current leakage.
5. Micro arc detection is crucial; if the test sees a tiny arc the unit should automatically stop the test.
6. Real-time display on the screen is a must; this allows the operator to see the voltage and current while the test is in operation. If the operator sees any abnormal condition, he/she can stop the test.

Case study: Step-Voltage testing
Exelon Nuclear, Limerick Station…
The Station Predictive Maintenance program at Limerick routinely performs electrical testing of large motors at a two-year frequency. This testing consists of winding resistance, insulation resistance, PI Capacitance/dissipation factor and DC step-voltage testing to 20kV. The resulting data has been tracked and trended for almost 20 years.

On a few occasions during 2002, Operations personnel reported that an "acrid" odor was present at the 1C Circulating Water Pump Motor. The PdM group had been tracking this motor on a "watch" list that came about as a result of an increasing trend in leakage current detected by DC step-voltage testing from 1997 to 2002 (see Fig. 4).

As part of its increased troubleshooting activities, the Limerick Station PdM team monitored the motor through the summer of 2002, utilizing acoustic monitoring and vibration and winding temperature/RTD monitoring on a monthly basis. In September 2002, an action request was made to replace the motor in the winter, based upon the electrical testing results, increasing vibration at stator slot frequencies and higher acoustic/ultrasonic "noise."

Once the motor was removed, it showed high leakage current on the "A" phase motor winding compared to the other two windings. After cleaning, a visual inspection of the winding identified partial discharge at the junction where the core slot winding tap transitions to the end winding/knuckle tape. Investigation revealed a lack of "proper" corona suppression tape at this critical junction point in the winding.

Among the lessons learned from this event was the fact that tracking and trending leakage current versus applied voltage on a DC Step- Voltage Test, as presented by the Baker AWA offline tester, can and does indicate potential problems in the winding. Furthermore, when this data is combined with other predictive technologies, it will allow for proactive replacement of a motor prior to an in-service failure.

Case study: Surge testing
Pulp & Paper Operation…
A 2300V form wound motor at a pulp and paper plant was found to have weak turn-to-turn insulation. Of all the tests performed on this motor, the only one that found the turn-to-turn weakness was the Surge Test. The controversy around surge testing, though, is that after finding a problem with insulation, could the tester have so degraded the motor that it would not run?

This Pulp & Paper industry case study easily puts this myth to rest. The motor in question was immediately put back in service after testing. It was started up and ran for the four months required until it could be shut down and removed for repair. Again, as noted in Fig. 5, the Surge Test was the only method to identify the insulation weakness. The problem was well above line voltage, so other lowvoltage tests would not have approached this threshold. (The surge summary in Fig. 5 highlights the fault weaknesses found with the tester.)

This particular Pulp & Paper site motor takes about 6-7 hours to change. Thus, it could have cost about $42,000 in downtime had the Surge Test not found the problem. Interestingly, 80% of all electrical motor failures begin with weak insulation turn-to-turn. The Surge Test is clearly the best method available to find this problem. That's why it is so important to perform this type of non-destructive testing on all motors.

Summary
The Step-Voltage and Surge Tests are necessary for an effective PdM program. They identify problems that low-voltage tests can't find.

As the case studies in this article have shown, both of these tests are non-destructive in that the tested units were returned to service until the next available time could be scheduled to replace them.

Finally, these tests are performed at voltage levels a motor is exposed to during normal operation. If a motor cannot pass the Step-Voltage and Surge Tests, you can bank on the fact that it is approaching the end of its service life. Consequently, provisions should be made as soon as feasibly possible to have that motor removed before unscheduled downtime occurs.

Joe Geiman holds a B.S. from Colorado State University in Industrial Technology Management. He travels extensively within the Western and Southeastern regions of the United States and has tested and analyzed hundreds of motors for a variety of industries. Telephone: (800) 752-8272 or (970) 282-1200; e-mail: jgeiman@bakerinst.com

Ken Bannister, Contributing Editor

Because of its use of consumable products and need for replacement maintenance repair and overhaul (MRO) inventory items, the Maintenance department must requisition and contract through the Purchasing department on a daily basis.

The approach toward procuring purchased items varies greatly from organization to organization. Large ones will often support a selfregulated purchasing group; medium to small organizations may rely on Maintenance to perform shared purchasing/expediting duties with a single buyer-or even relinquish all purchasing duties to a contracted third-party inventory-management company. Regardless of the approach, building a workable Maintenance/Purchasing relationship will depend greatly on how well the following types of complaints are managed.

Examining typical complaints from the perspective of both partners leads to the formulation of a workable approach that allows Maintenance to focus on delivering equipment availability and reliability, and Purchasing to focus on procuring products that deliver the best value for the least amount of expenditure.

Typical Complaints #1
Maintenance: "Purchasing never recognizes the urgency of our purchasing needs, requiring us to take our own measures to ensure the part gets here fast enough, especially on a breakdown job when the line is down and we need the parts here now!" Purchasing: "Maintenance always is trying to side-step the procurement process and expedite parts behind our back, often agreeing to outrageous delivery costs to get things here faster."

Solution…
Unfortunately, many Maintenance organizations are still purchasing items as a direct result of reactive situations. Maintenance departments that actively engage in proactive maintenance strategies (preventive, predictive, condition-based) linked to the planning and scheduling of maintenance events are better able to provide Purchasing with enough lead-time fl exibility to procure the part with the best delivery option (no more expensive air freight or taxi delivery charges).

Clearly defining the role(s) of each department (Maintenance/Purchasing) allows any size organization to map out the procurement business process specific to the organization, as well as set up clear levels of responsibility. Using a template similar to that shown in Fig. 1, both departments meet to discuss which department is best suited to take on what role based on expediency and ability to perform the role. With roles decided, the workfl ow is now diagrammatically mapped indicating the responsible department for each action. This enables both departments to follow a structured approach and commence working trust in one another.

Typical Complaints #2
Maintenance: "Purchasing always buys the cheapest product or service it can find." Purchasing: "Maintenance doesn't understand that we have a mandate to continuously reduce purchasing costs."

Solution…
Establishing MRO-item purchasing programs based on Life-Cycle Costing (LCC) is paramount for reducing downtime costs, equipment repair costs and procurement costs. An LCC program begins with both departments understanding the fundamental difference between price and cost.

When purchasing a replacement MRO item, price is the money paid to receive a quality item FOB (Freight On Board) at your plant, through regular shipping methods.

Cost is attributed to the equation when additional money is spent without value, as depicted in the following scenarios:

• Price plus additional money for emergency shipping
• Price plus additional money spent to administer and wait for the return of defective, inferior quality items
• Price plus additional money spent for accelerated replacement and incurred downtime costs of less expensive, inferior quality items (lower cost items with lower Mean Time Between Failure [MTBF] life-cycle reliability ratings)

Purchasing the least expensive item may make sense initially when buying on price alone, as indicated in the Fig. 2 examples. Product A, priced at $10, is twice the price of the $5 Product B. Purchasing Product B over A gains an immediate 50% price saving.

However, taking life-cycle expectancy into account changes the scenario considerably.

Product A has a life expectancy of three years, whereas Product B is a lower-quality manufactured part with an expected life expectancy of only one year. Over a three-year period, Product B is changed out three times compared to Product A, which actually increases the purchase price by 50% over the life-cycle of the more expensive part (1 x $10 expenditure vs. 3 x $5 [$15] expenditure).

Furthermore, purchasing the lower-quality Product B incurs two more sets of additional costs associated with downtime of the equipment, maintenance replacement costs, purchasing administration costs, work order administration costs and inventory management costs over the life cycle of Product A.

Working together to understand and make buying decisions based on Life-Cycle Costing dramatically reduces operations, maintenance and purchasing costs.

Typical complaints #3
Maintenance: "Purchasing never seems to purchase the right part."

Purchasing: "Maintenance never gives us the correct information to order in the correct part."
Solution… Once again, clear lines of communication are vital to attaining mutually desired outcomes. Setting up a minimum information requirement for the purchase requisition, preceded by a detailed part specification standard, as outlined in the Fig. 1 template, will significantly reduce the chances of an incorrect part purchase.

Typical complaints #4
Maintenance: "We always get blamed for downtime."
Purchasing: "Downtime is not a purchasing problem."

Solution…
Downtime is everybody's problem. This becomes more apparent when a Value Stream Map is created for the organization depicting intra-department input/output relationships. Taking a facilitated approach, both Maintenance and Purchasing must work together to become consistent in their methods of procuring and using parts. We already have seen that purchasing parts based on LCC can signifi- cantly reduce downtime-something that is brought about through understanding and collaboration between Maintenance and Purchasing. Other collaborative acts resulting in cost reduction can include:

• Initiating a preferred vendor or supplier program based on quality products, service, delivery and reasonable pricing policy
• Developing a parts specification book based on existing preferred parts and vendors that have historically shown good life-cycle tendencies
• Involving Purchasing in Maintenance planning and scheduling meetings

Purchasing is a very important part of your equipment maintenance process. Thus, it is well worth the investment to create a cooperative environment between your Maintenance and Purchasing groups.

Ken Bannister is lead partner and principal consultant for Engtech Industries, Inc. Telephone: (519) 469-9173; e-mail: kbannister@engtechindustries.com

Ask many maintenance engineers what the major contaminant in their compressed air system is, and their answer would be oil. Oil is perceived to be the greatest cause of contamination in these systems because it can be seen emanating from open drain points and exhaust valves. Most of the time, however, what may look like oil actually is oil condensate (oil mixed with water).

In reality, nearly 99.9% of the total liquid contamination found in a compressed air system is water, with oil being only a very small part of the overall problem. A small 100 cfm compressor and refrigeration dryer combination, operating for 4,000 hours in typical northeastern U.S. climate conditions, can produce approximately 2,200 gallons of liquid condensate per year- a staggering amount. Filter systems can remove oil and dust, but well maintained air dryers are required to remove water and adjust humidity levels.

Sources of contamination
Contaminants in the compressed air system generally can be attributed to:

• The quality of the air drawn into the compressor
• The operation of the air compressor
• Compressed air storage devices and distribution systems

Air quality...
Air compressors draw in large amounts of air from the surrounding atmosphere that contains a large number of airborne contaminants, including atmospheric dirt, micro-organisms, oil vapor and water.

In an industrial environment, there are 140 to 150 million particles of dirt in every cubic yard of air. Eighty percent of these particles are too small to be captured by compressor intake filters. Consequently, they pass directly into the compressed air system.

Bacteria and viruses also are brought into the compressed air system. The warm, moist air provides an ideal environment for the growth of micro-organisms. Ambient air typically contains up to 3,850 micro-organisms per cubic yard. If only a few of these bacteria or viruses enter a sterile process or clean production system, enormous damage could result, diminishing product quality or even rendering a product unfit for use and subject to recall.

Air also contains oil in the form of unburned hydrocarbons that are drawn into the compressor intake, as well as vaporized oil from the compression stage of a lubricated compressor. When these vapors cool and condense, they cause the same contamination issues as liquid oil.

Water vapor, condensed water and water aerosols from the atmosphere can wreak havoc on a compressed air system. The air's ability to hold water vapor is dependent upon its temperature. As the temperature increases, the level of water vapor that is held by the air increases. It takes 7.8 cubic feet of free air to generate 1 cubic foot of compressed air @ 100 PGSI. During compression, air temperature is increased significantly, which allows the air to easily retain incoming moisture. Significant amounts of water, as well as the other previously mentioned contaminants, enter the compressed air system without proper protection.

Air compressor operation…
The air compressor itself can add contamination, from wear and tear particles to coolants and lubricants. Rust and pipe scale can be found in air systems without adequate air dryer systems. Over time, this contamination breaks away and causes damage or blockage in production equipment and may also contaminate final products and processes.

Almost all air compressors use oil in the compression stage for sealing, lubrication and cooling. Some oil, in liquid or aerosol form, enters the compressed air system and mixes with water vapor, which can cause damage within the system. The amount of oil in the oil/water mixture accounts for less than 0.01% of the overall volume. But it is this resemblance to oil that leads to the mistaken belief that oil is the major contaminant in compressed air systems.

Storage and distribution…
After the compression stage in a system, air is typically cooled to a usable temperature, reducing the air's ability to retain water vapor. A proportion of the water vapor condenses into liquid water and is removed by a drain fitted to the compressor after-cooler.

Additional condensation, however, occurs in the compressed air system because the air continues to be cooled by the air receiver, piping and the expansion of air in valves, cylinders, tools and machinery. Condensed water and water aerosols can cause corrosion to the storage and distribution system, as well as damage to production machinery and an application's end products. Liquid water also can wash away prelubricants on cylinders and valves, decreasing their operational life. Furthermore, water in a compressed air system reduces production efficiency and increases maintenance costs. Removing liquid water and water vapor from such a system helps ensure that it runs properly and efficiently.

Purification technology overview
Coalescing filters are probably the most important purification equipment in a compressed air system. They are designed to remove aerosols (droplets) of water and oil using mechanical filtration techniques. Coalescing filters have the additional benefit of removing solid particulate to very low levels (as small as 0.01 micron in size). To be effective, they should be installed in pairs. Both filters perform the same function, with the first-a general-purpose filter-used to protect the second-a high-efficiency filter-from bulk contamination. This dual filter installation ensures a continuous supply of high-quality compressed air with low operational costs and minimal maintenance requirements.

The next component in the compressed air system is the air dryer. Properly maintained air dryers remove moisture from the compressed air system, eliminating condensation in the system's piping, pneumatic tools and instruments. There are two basic types of air dryers: refrigeration and adsorption (desiccant). A dryer's efficiency is measured as the dew point, which is the level of dryness in a compressed air system.

Refrigeration dryers (such as the one shown in Fig. 1) cool air to a pressure dew point of 35 F, which is the effective limit on this type of dryer because water freezes at 32 F. This style of dryer is ideal for general industrial applications in light assembly, including those that use air motors, air tools, valves, cylinders and rotary actuators, painting and welding equipment, to name a few. Refrigeration dryers are not suitable for installations where piping is installed in ambient temperatures below the dryer dew point (i.e., systems with outside piping).

Adsorption (desiccant) dryers (like those shown in Fig. 2) pass the air over a regenerative adsorbent material that strips the moisture from the air. These types of dryers are extremely efficient and can provide a pressure dew point as low as -100 F, with a typical range of -40 F. Desiccant dryers remove liquid from the compressed air system through the use of chemical beds. They often are used in cold-weather pneumatic applications, such as mining, agriculture, utilities, pulp and paper and transportation.

It should be noted that refrigeration and adsorption dryers are designed for the removal of water vapor, NOT water in liquid form. To work efficiently, air dryers require the use of coalescing filters installed in front of them in the compressed air system.

Other types of filters include:

• Adsorption filters-Oil vapor passes through a coalescing filter just as easily as compressed air. These filters, which provide a bed of activated carbon adsorbent, remove oil vapors and provide protection against oil contamination.
• Dust removal filters-These are used to remove particulates when no liquid is present. They perform to the same level as the system's coalescing filters.
• Microbiological (sterile) filters-A sieve retention or membrane filter removes solid particulates and micro-organisms. These filters are often referred to as sterile air filters because they provide sterilized compressed air.

Maintaining compressed air systems To achieve the stringent air quality levels required for today's production facilities, a compressed air maintenance system must be employed. Air-treatment maintenance should address the complete compressed air system. It is highly recommended that compressed air be treated to a quality level suitable for protecting air receivers and distribution piping prior to entering the distribution system. Maintenance programs should be tailored to the type of compressed air system, size of connecting lines, water capacity, flow capacity (system size), filtration capability, construction material of air dryers (i.e., steel or copper) and safe working pressures. Evaluation of each factor helps ensure proper and economical compressed air system operation. Low-pressure dew points derived from proper maintenance of air dryers and other purification technologies help to prevent corrosion and inhibit the growth of micro-organisms within the compressed air system. Well-maintained air dryers and purification components also help minimize pressure loss in the air system, a major contributor to operational costs, thus reducing energy consumption. Finally, air dryers that are maintained properly have a longer life cycle, reducing production downtime, while contributing to increased output and profitability.

Mark White is a product manager with domnick hunter Ltd., a division of Parker Hannifin. Rick Hand is FRL product manager with Parker Hannifin Corporation. For more information, e-mail: mark.white@parker.com or rhand@parker.com