Archive | Oil Analysis

3

10:01 pm
June 22, 2017
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Oil Sampling

1704mtprod13pThe Simplo jar uses a vacuum inside the bottle to draw fluid from within the component without opening the bottle and exposing the sample to environmental cross contamination. Made of high-density PETG and designed for lubricants within any viscosity range, the average cleanliness for each jar is ISO (4406) 11/9/4, NAS (1638) 1 that ensures samples drawn accurately reflect the component’s condition. The sampling process is virtually hands-free since the pre-charged vacuum automatically draws the sample and prevents spillage.
RelyAssist
Broken Arrow, OK
relyassistllc.com

272

7:42 pm
April 13, 2017
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Top Tips For Maintaining Air Compressors

Use these tips to improve air-compressor performance and increase uptime.

Use these tips to improve air-compressor performance and increase uptime.

Air compressors and their output are valuable assets on which countless plants depend for efficient daily operations. Regular attention to and proper management of the health of these critical equipment systems can save time and money in all manufacturing systems.

John Skalka, service manager for Sullair (Chicago) offers several tips for maintaining your site’s air compressors. According to Skalka, following these procedures to help monitor and maintain air-compressor performance can result in reliable equipment and reduced downtime.

—Jane Alexander, Managing Editor

Maintain filters and separators.

Proper maintenance of a compressor’s consumable filters and separator elements will not only help to ensure maximum unit uptime, but also maximize its efficiency and performance.

Air intake and oil-filter maintenance should be conducted every 2,000 hr. Monitor the oil filter for contamination and wear metals, leading indicators that air-end maintenance is required.

Air/oil separator elements should be changed every 8,000 hr., along with compressor fluid. Proper air/oil separator maintenance will ensure oil carryover stays within the manufacturer’s specifications.

Remember that use of OEM service parts and lubricants in compressor maintenance will help ensure optimal equipment performance.

randmSample oil.

Regularly acquiring and analyzing oil samples helps monitor the condition of the compressor lubricant, as well as the unit itself. A robust oil-sampling and monitoring program will alert the user to fluid degradation resulting from increased viscosity, ingestion of chemicals or particulate, and high water content. It can also identify the presence of wear metals, which is a sign of bearing degradation, prior to catastrophic failure.

Oil-condition monitoring makes it possible to change the lubricant only when necessary to maintain peak performance. Samples should be drawn quarterly, during routine service maintenance on a compressor.

Remember to always draw your samples through a clean oil-sample port or from the center of the oil sump. Doing so will ensure that the results are free from particulate contamination.

Keep variable-speed drives clean.

Many of today’s compressors are equipped with a variable-speed drive (VSD) that increases efficiency and reduces energy consumption. While VSDs are electrical components, they are not completely maintenance free.

Most VSDs contain cooling fans and heat sinks that can accumulate dust and dirt during regular operation. Maintenance activities will help them run cooler and prolong their service life.

Eliminate the guesswork.

For plants that are unable to ensure regular compressor maintenance with in-house resources, outside support is available. Check with your local air-compressor sales and service center about plans that allow skilled, factory-trained technicians to routinely service your compressor(s) and related air-system equipment.

Finally, keep in mind that proper maintenance will help you realize years of reliable service from your compressor. MT

Sullair, part of Accudyne Industries (Luxembourg and Dallas, accudyneindustries.com) has been developing and manufacturing air compressors since 1965. For more information, visit sullair.com.

162

6:03 pm
April 13, 2017
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A Hoarder of Information

When it comes to lubrication, Scott Arrington relies on 34 years of information gathering to ensure he always has the correct answer for his customers.

High-tech equipment helps Arrington and his team provide accurate analysis and improve the reliability of all equipment.

High-tech equipment helps Arrington and his team provide accurate analysis and improve the reliability of all equipment.

By Michelle Segrest, Contributing Editor

Screen Shot 2017-04-13 at 12.24.37 PMScott Arrington is a hoarder—a self-described hoarder of information, that is. The World Wide Web is not big enough to hold all the information upon which he relies. In fact, he has so many manuals, binders, and oil samples, he needs two offices—one to work in, and another to contain all the valuable records, documentation, and research he will never throw away.

Arrington is the Lubricants Technical Manager at G&G Oil Company, Muncie, IN. When a customer calls with a question, he wants to be sure he has the correct answer. “I have abundant resources to make sure we make the correct recommendation the first time and can quickly answer questions from customers. I keep all records of opportunities we have already experienced.” 

As a college student, Arrington worked part-time for the company painting convenience stores, bumper poles, and canopies, and performing maintenance.

“It was a great summer job, and it helped me to get familiar with the business,” Arrington said. “When I graduated from Depauw University (Greencastle, IN) in 1986, I was still looking for a full-time job and the owners of G&G Oil (Bill Gruppe, deceased; Hoyt Neal, retired; and Dale Flannery, retired) were gracious enough to allow me to come work for them in a sales position. They helped me get interviews with a couple major oil companies. I received some nice offers, but when I measured what I really wanted to do and where I really wanted to be, staying here was the best option for myself and my family.”

When making that crucial decision, the opportunity to work with people and with a smaller company were key factors.

“When I graduated from college with my science and physics background, I knew I didn’t want to spend my life in a lab,” he explained. “I was looking around at different options and the owners of G&G Oil offered me a position where I could use my science background to help sell lubricating products while not being tied down to a desk. I was able to get out in the field and see many different and interesting mechanical operations. It was something new every day.”   

Thirty-four years later, Arrington remains loyal to G&G Oil, and now makes significant contributions—in particular with his deep technical knowledge and impact on the lubrication and oil-analysis programs. 

1704fvoice04pMajor responsibilities

It is Arrington’s passion to help customers and prospects solve lubricant-related issues. “From my numerous years of experience and attendance at many major oil companies’ learning seminars, I have been able to absorb quite a bit of knowledge to assist companies and individuals with their lubricating problems,” he said. “I can also assist them with ideas and programs to decrease their total lubrication expenses.”

It is Arrington’s responsibility to answer technical questions from customers and prospects, working directly with key accounts, assisting salespeople with technical sales calls, maintaining current formulas and developing new products, maintaining and updating technical data sheets, approving all raw materials used in formulations, and approving new finished products that G&G distributes for other companies. 

Arrington’s team includes a customer-service manager, a logistics manager, a production manager, and a sales manager. He also works closely with the sales representatives to make sure they are supported with sales opportunities and assistance with current customer questions.

Many of the customer’s questions include inquiries about machine recommendations. “Customers will call in with questions about a certain brand of product for a certain machine,” Arrington explained. “I will delve into the exact specifications of the product they are telling me about and come up with a recommendation of a product we represent—whether it is a G&G Oil-branded product, a Shell Oil-branded product, or from many of the other brands of products we distribute. I try to take away the aura of the name of the specific brand, and assure them that if you don’t have that exact brand, the machine will not keel over and die. I educate the customer about my recommended product and that their warranty won’t be voided if they use another product brand. The warranty will still be in good standing by using the specification of the product, and not necessarily the brand of that product, in their machinery.”

Screen Shot 2017-04-13 at 12.24.49 PMThe importance of lubrication

Arrington said he lives and breathes with a simple philosophy—“Learn all you can, and don’t be afraid to ask questions.” For him, the importance of good lubrication is simple.

“If you don’t have proper lubrication in your equipment, it won’t run the way it’s designed, which will lead to unscheduled maintenance opportunities,” he explained. “If your machinery doesn’t run, you can’t make products to sell. If you can’t make products to sell, your business will suffer and you possibly won’t be around very long! If you are using improper lubrication practices, your machinery will not run at the optimum level. Your maintenance costs will go up because you will have to replace components more often and you will have more unscheduled downtime. Your total maintenance spend will increase if you are not using the correct lubrication product and applying it at the right time, or monitoring it at the right times to make sure your machinery is running at its optimum level.”

Arrington recommends the following lubrication best practices:

• Follow OEM instructions.

• Develop an oil-analysis program that emphasizes:

• condition of the machinery
• trending how the machinery is functioning
• tracking excessive wear of components
• information about the oil (oxidation, contaminants, additives).

If you don’t have your own in-house oil-analysis laboratory, partner with a reputable and certified independent oil-analysis provider. Even if you have your own lab you should use an independent lab to occasionally check your results.

• Use different testing procedures to ensure customers can fully see the condition of their machinery.

• Use proper sampling equipment and procedures.

“A good oil-analysis program is like having a blood test for a human. It can tell you if you have problems with a vital organ or some other part of your body that you may need to look into to take medicine for or have surgery,” Arrington said. “It’s the same with oil analysis—it tells you if the ‘organ’ in the machine is running properly or if it needs to be examined or replaced because it may have excessive wear or other problems, causing it not to work to its optimum level. A good oil-analysis program allows you to be proactive to schedule maintenance instead of being reactive to a break down.”

scottgraphic

Challenges

One of Arrington’s biggest challenges, he said, is developing and producing formulas for new products that G&G Oil can offer to its customers. 

“It’s challenging because of the many different obstacles you’re trying to overcome, especially in the metal-working and metal-removal fluids field. You’re trying to formulate a product for the customer that will have a long life span for the fluid, a good clean finish for the part, and will provide long tool life,” Arrington explained.

There are several different types of additives that can be used, depending on what kind of metal is being manipulated or type of operation being performed. “You have to use the correct balance of those additives to give you an optimum performing product,” he said. “I rely heavily on my additive manufacturers to give me guidance. When I have special projects, I consult with them. I design a product in the lab and then collaborate with my suppliers to get their opinion on whether they think it will work or not.  Fortunately they agree with me most of the time! The formulating depends a lot on what the application is. You have a pool of additives and base oils that you know about. It’s just trying to blend them together correctly to give you the best-performing product for the customer.”

Finding inspiration

Learning and then hoarding information provides constant inspiration for Arrington. As an example, he points to the adage, “Give a man a fish and feed him for a day. Teach a man to fish, and feed him for life.” It is advice he implements in his own work, every day.

Arrington has been married to Stephanie for 20 years and has two teen-aged daughters, MiMi and Ellie. He gives similar advice to his children.

“I’m sure they get tired of it,” he said. “I try to give them advice of the failures I have had in the past—no matter how big or how small—and remind them how important it is to learn from them. I also try to get them to look at the big picture. I want them to see the repercussions of their actions. It may seem like a small thing, but it could be a big thing down the road. I try to be a great representative of myself and my family and my company. My children are growing up in a different time with different challenges and problems, but we all need to learn from history and our mistakes.” MT

Michelle Segrest is a professional journalist and specializes in the industrial processing industries. If you know of a maintenance and/or reliability expert who is making a difference at their facility, send her an email at michelle@navigatecontent.com.

350

4:15 pm
April 13, 2017
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Reliability Changes Lives

Using skilled technicians and advanced technology, Eli Lilly and Company creates life-saving medicines and devices worldwide.

By Michelle Segrest, Contributing Editor

Throughout the halls of the Indianapolis Eli Lilly and Company facility, the corporation's brand is proudly displayed. All photos courtesy of Eli Lilly and Company.

Throughout the halls of the Indianapolis Eli Lilly and Company facility, the corporation’s brand is proudly displayed. All photos courtesy of Eli Lilly and Company.

At Eli Lilly, the motivation to improve production reliability is not just something that is tracked on graphs and charts for upper management to review. In fact, for maintenance and reliability engineer Carrie Krodel, it’s personal.

Krodel, who is responsible for maintenance strategies at the Eli Lilly Indianapolis facility’s division that handles Parenteral Device Assembly and Packaging (PDAP), has a family member who uses the company’s insulin. “I come to work every day to save his life,” she said. “Each and every one of us plays a part with reliability. Whether it’s the mechanics or the operators keeping the line running, the material movers supplying the lines with the products, or the people making the crucial quality checks, everyone is a part of it. And we all know that the work we are doing is changing lives.”

The Indianapolis site covers millions of square feet with nearly 600,000 assets that must be maintained. According to Rendela Wenzel, Eli Lilly’s global plant engineering, maintenance, and reliability champion, the company produces the medicine as well as the packaging for insulin pens, cancer treatments, and many other products and devices.

For the entire Eli Lilly team—which includes a group of about 80 engineers at the Indianapolis site—the responsibility is crucial. “If we mess up, someone gets hurt,” Wenzel said. “This is a big responsibility.”

However, it’s the human element of this responsibility that inspires an exceptional level of quality.

Team, tools, training

Screen Shot 2017-04-13 at 11.03.07 AMWayne Overbey, P.E., is the manager of the Maintenance-Manufacturing Engineering Services department. He said his team of seven maintenance technicians uses three primary technologies every day to keep the machines running—vibration analysis, oil analysis, and infrared technology. With a focus on condition-based monitoring, each team member has an area of responsibility to collect and analyze vibration data. In addition to the vibration data collector, each team member carries a small infrared camera to make heat-signature images used to diagnose and troubleshoot rotating-equipment problems.

The team also uses a digital microscope that can zoom to 3500X magnification. This helps them look closely at a bearing race, cage, and rolling elements and see what caused a failure, whether structural, corrosion-based, or failed lubrication. In addition, the group has an oil laboratory that can analyze oil and grease. 

The team performs more than 7,000 measurements on more than 4,000 rotating/reciprocating machines and performs vibration analysis on those machines monthly, Wenzel stated. The level of qualified individuals is high. “Anything that is process related, we have the equipment to look at it and analyze it,” she said. “We have people with ISO 18436-2 Cat 2 and Cat 3 verifications and even one expert with an ISO18436-2 Cat 4 certification, and there are fewer than 100 people globally with that level of certification. These guys are experienced, high-level certified professionals.”

The maintenance team increased its level of performance more than five years ago when it made the strategic decision to outsource the facilities (buildings and grounds) portion of maintenance. With about 220 maintenance professionals companywide at the Indianapolis facility, this allowed the team to focus more on production and analysis rather than the facilities, Overbey said.

The team has sophisticated data-collection routes set up as PMs and also focuses heavily on maintenance training.

“We have a difficult time finding people interested in maintenance,” Overbey said. “We have a strategic program to train people that takes 18 months to 2 years. When I was growing up, being an electrician or mechanic was a fine career, but now the attitude is that you have to have a college degree to be successful. Most of our crafts people here make more than the average liberal-arts major. As we cycle out the baby boomer work force, we need to find new talent and close the gap.”

Wenzel agreed that finding qualified crafts people has been a focus that has helped Eli Lilly in its drive for reliability.

“Wayne saw the need and developed an excellent program,” she said. “Management is supportive. He is training them and then sending them to get experience while they are going to school.”

The program is responsible for hiring 24 trainees, to date, and has been able to place 18 of them in full-time positions within Lilly maintenance groups. The remaining six trainees are still in the initial stage of the program. The training also uses basic maintenance programs provided by Motion Industries and Armstrong. Last year, there were more than 30 well-attended training classes focused on equipment used at Lilly. The company wants the training to be relevant to what the maintenance technicians perform on a daily basis.

“The whole condition-based platform makes us unique,” Wenzel said. “We have all the failure-analysis competencies. It’s a one-stop shop. We provide two-to-three day courses on condition-based technologies for crafts and engineers. The whole understanding, as far as what maintenance and reliability can do, is to increase wrench time and uptime. We are all seeing an uptake in technology.”

The Indianapolis Eli Lilly facility has more than 600,000 assets that must be maintained by its experienced engineering-services team.

The Indianapolis Eli Lilly facility has more than 600,000 assets that must be maintained by its experienced engineering-services team.

Best practices

Overbey stated that his main responsibility is to help the various site-maintenance groups improve uptime by using diagnostic tools to identify root causes of lingering problems. With a focus on training paying dividends, he said the high-quality people are what make the condition-based monitoring team successful.

The team works with the site-maintenance groups to reduce unexpected failures, so increased time can be focused on preventive maintenance. “We look at our asset-replacement value as a function of our total maintenance scheme,” Wenzel said. “We look at recapitalization and make sure we are reinvesting in our facility. We keep track of where we are with proactive maintenance. Those numbers are tracked facility to facility and then rolled into a global metric.”

Vibration analysis and using infrared technology has become a central part of the department’s reliability efforts.

“These guys have taken responsibility for the failure-analysis lab and taken it on as an added-value service,” Wenzel said. “For example, if there is a failed bearing, they take it out, cut it up, and provide a report that goes back to management. If we make a call that a piece of equipment has increased vibration levels and is on the path to failure, based on the vibration data collected, getting those bearings goes a long way in getting site buy-in when the actual bearing problem can be visually observed. Most individuals are skeptical when shown the vibration waveform (squiggly lines), seeing the bearing with the anomaly is the true test of obtaining their buy in.”

“We can compete with anyone in terms of oil analysis,” Wenzel added. “We can identify particles and have switched to synthetics. For example, when oil gets dirty, it becomes acidic. Something slightly acidic can be more harmful than something that is highly acidic because it will just continue to eat away at the material and cause significant damage before you can stop it. Something slightly acidic can really tear up bearings. The FluidScan 1100 can detect that.”

Screen Shot 2017-04-13 at 11.03.19 AM

More than 80% of the oil samples are now handled internally, Wenzel said. “As we are selling all of these capabilities to the PdM team around the world, we are starting to look at some of the potential issues at other facilities to provide extra analysis with this condition-based maintenance group,” she said. “We are sharing good ideas and processes across facilities. We now have a maintenance and reliability community.”

Eli Lilly employs Good Manufacturing Practices (GMP) and the use of many chemicals requires a high level of cleanliness that is checked daily and regulated by government bodies.

Changeovers can often take weeks. “We check everything,” Wenzel said. “There is very involved and stringent criteria for how we clean a building. Regulations are a challenge, but they keep you on your toes. You don’t even notice it anymore because it becomes a part of what you do. It doesn’t faze the day-to-day thinking.”

The precision and accuracy of the facility's manufacturing equipment contributes to its product excellence.

The precision and accuracy of the facility’s manufacturing equipment contributes to its product excellence.

Operational excellence

Eli Lilly works with cross-functional teams in which maintenance, engineering, and operations are working on the overall process. Operations manager Jason Miller is responsible for running the process. Maintenance corrects the issues and performs preventive maintenance to get ahead of equipment failures and prevent unplanned downtime.

“Anytime we have an equipment failure we evaluate what happened and see what process we can put in place to get ahead of those things,” Miller said. “Line mechanics are on each shift and work with our line operators to understand and troubleshoot issues. We get ahead of issues to ensure [there is] no impact to the quality of our process.

With advanced robotics and a large amount of automation, monitoring performance and quality is key to successful operation and production, Miller stated. “Everything is captured, including downtime and rejects,” he explained. “We identify corrective actions at every morning meeting. We use the data on the line to drive improvement. The line is automated, but if there is a reject every 100 cycles, we need to take action. The robotics never stop. If you see overloads or rejects over time, this tells you about mechanical wear and other issues with the equipment. We drive data-driven decisions for maintenance.”

The preventive maintenance includes lubricating linear slides each month. When vibration is detected, adjustments are made immediately. “The machines tell us what’s going on. We just have to know how to read them,” Miller said. “We have manual and visual quality checks, but the machines also do quality checks. Reliability is critical because when patients are waiting on their medicine, the machines have to run the way they are supposed to run all the time. We have standards, and they have to be precise. This is medicine going into someone’s body. We are the last step of the process. It has to be packaged and labeled correctly, as well.”

Mike Campbell is the maintenance planner and scheduler for PDAP and has developed a system in which all preventive maintenance is performed during scheduled shutdowns.

“We develop a schedule with every piece of equipment and every scheduled PM associated with it,” Campbell said. “One line may have 50 to 60 PM work orders to perform during the week of the scheduled line shutdown. We bring in a lot of resources to do it all at once, typically requiring a day shift and a night shift.”

Advanced production technology is critical to the standard of reliability excellence.

Advanced production technology is critical to the standard of reliability excellence.

Changing lives with reliability

Wenzel said that looking at how each department interacts helps to put all the pieces of the reliability puzzle together. They have even received outside recognition of their practices in Indianapolis. In 2008, The Corporate Lubrication Technical Committee, of which Wenzel is the chair, won the ICML John Battle Award for machinery lubrication.

“It’s not only a cost piece, there is a whole asset-management piece and a whole people piece that we have to look at–not just the numbers, the metrics, the bars and charts–it’s the whole thing that makes a facility tick,” she explained. “Reliability isn’t just my job…it is everyone’s job. Every time I get into my car and turn the key, I expect it to come on. Every time I run that piece of equipment, I want it to perform the same way every time. That, to me, is reliability.”

Overbey said reliability is about being tried and true. “It’s predictable. It’s reliable every day. It’s the whole conglomeration of things that is very complicated, yet very simple. When all is said and done, reliability is a huge advantage for a company. You are only spending money when you need to. But it’s very difficult to get there.”

Wenzel said that consistency is a key to reaching reliability goals. Eli Lilly has global quality standards and good manufacturing practices that are applicable to each of the company’s sites across the world.

“Reliability means the equipment is ready each and every time it runs, and it should perform the same way each time,” Krodel said.

Doug Elam is Level 4 vibration certified, which is a rare level of qualification. He works on Overbey’s team and also tried to define reliability. “Reliability is an all-expansive subject that touches on different types of technology, the goal of which is to improve efficiency in machinery performance,” Elam said. “It requires an intense study of the background functions of the machines.”

Eli Lilly and Company uses robots on an assembly line to carefully package its products.

Eli Lilly and Company uses robots on an assembly line to carefully package its products.

Regardless of the definition, reliability for Eli Lilly always circles back to the human element.

“Patients come through and perhaps are on insulin or a certain pill, or a cancer treatment that has changed their lives,” Wenzel explained. “We listen to them, because it’s not just the medicine that matters, but the packaging and ease of use. It puts what we do in perspective. We take this feedback and incorporate it into our designs. It starts with an end user’s idea and need, goes to design, goes through production, then back to the end user. It’s like a circle of life.”

The research is carefully conducted with the end user always in mind.

“A lot of research is done to make the best fit for each subset of people,” Wenzel continued. “And at the end of the day you have a marketable product that you can be proud of. Being on both sides of the business, you understand why medicine is so costly. But when you find the one niche that helps cancer patients, or the kid who is near death, and then you can be a part of developing this medicine that completely changes his life, it just makes it all worthwhile.”

And yes, it’s personal.

“When you know people who use the products,” Wenzel said, “the work you do becomes a part of you.” MT

Michelle Segrest has been a professional journalist for 27 years. She specializes in the industrial processing industries and has toured manufacturing facilities in 40 cities in six countries on three continents. If your facility has an interesting maintenance and/or reliability story to tell, please contact her at michelle@navigatecontent.com.

435

8:17 pm
August 9, 2016
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Practical Oil Analysis: Why and What For?

Simply hoping your lubricants are operating  within their protective-specification limits doesn’t make it so.

By Ken Bannister, MEch Eng (UK) CMRP, MLE, Contributing Editor

Lubricants are designed and chosen to perform as finite and perishable, integral components of host machines. Rarely, if ever, will a lubricant be employed in identical application and environmental conditions. Enter oil-analysis testing.

Why we test

The uniqueness of lubricants reflects how and when they must be tested, maintained (filtered and temperature controlled), and changed out. Stresses and influences such as load-induced shear stress, thermal degradation, various types of contamination, and wear-metal-catalyzing alter and prematurely degrade lubricant properties.

Oil is made up of a base oil and an additive package that’s designed to combat ambient and working environmental stresses/influences and deliver reasonable lubricant life. Outside stresses produce an array of detrimental effects, including oxidation, polymerization, cracking hydrolysis, and evaporation that manifest as thickening or dilution of viscosity, acid buildup, and sludge. Additionally, when oil loses some of its protective ability, its host bearings can come into contact with one another and release metal-wear particles into the lubricant, which then act as a bearing-attacking abrasive material (three-body abrasion).

These effects and conditions are why we analyze oil. This testing is how we ensure lubricants are serviceable and bearing surfaces are protected.

Screen Shot 2016-08-09 at 3.15.01 PMWhat we test for

Oil analysis is analogous to a blood test wherein a single, properly extracted fluid sample is used for a variety of diagnostics that indicate machine and lubricant conditions. To ensure an accurate interpretation of results every time—reliable ones suitable for trending and historical analysis—samples must be collected in a consistent manner and sent to the same laboratory for testing on the same equipment.

The lab will also require a virgin sample of any lubricant to be tested. This sample is used to document baseline measurements of base-oil type, additive-package levels (metals and chemicals), cleanliness level (dirt-contamination level), and viscosity and acidity. A set of initial samples detailing how and where each was taken will also be required for each machine.

Good laboratories also document an operational profile for each machine tested. Based on it, they can recommend additional beneficial testing, e.g., a Karl Fischer water-contamination test for a food plant with daily machine wash downs; tests for soot and glycol in mobile equipment and generator engines; or ferrographic analysis of metal particulates to determine specifically how a bearing is failing.

Basic oil analysis concentrates primarily on fluid property and fluid contamination.

Fluid-property testing

In analyzing fluid properties, laboratories typically look at viscosity, acidity, and additive elements—the “big three” characteristics that make oils unique—and which, through their changes in service, can tell us how to better maintain our lubricants.

Viscosity. The viscosity rating of new oil is typically measured in centistokes (cSt), i.e., oil’s kinematic viscosity depicting measured resistance to flow and shear by the force of gravity. As oil thickens or dilutes over time, however, its specific gravity changes, leading to errors in gravity-based tests. A more consistent measurement is achieved by checking for the absolute viscosity rating depicting oil’s resistance to flow and shear through measurement of its internal friction. Because absolute viscosity is measured by multiplying kinematic viscosity by the actual specific gravity, it’s an accurate, error-free trending method of choice for most laboratories. To understand which tests your lab used, note the measurement scales: kinematic viscosity (good test) is measured in centistokes (cSt), absolute viscosity (best test) in centipoise (cPs).

Given oil’s many variables, it’s best to work with a laboratory that’s experienced in setting up caution and critical limits for your industry type. Most labs typically start with a clearly defined set of viscosity limits of –10% CL (critical lower), –5% CaL (caution lower), +5% CaU (caution upper), and +10% CU (critical upper) for industrial oils. In more severe environments, the CaU and CU limits can be reduced to +4% and +8%, respectively. For oils with viscosity improvers, the lower limits are usually doubled.

Thickened, more viscous oil points to oxidation (depleted additives), air entrainment, and/or contamination. Thinner, less viscous oil points to a wrong substitution or fuel dilution. 

Acidity. The acid number, or AN, is a measurement of the acid concentration in the oil, not the acid strength, and is greatly affected by the presence of water within the oil. Most oils start with an AN of less than 2.

Setting limits for acidity isn’t as easy as setting those for viscosity. The caution and critical limits are dependent on the type of additive package used in the oil. Most standard mineral oils are considered corrosive over AN 4, whereas AW (anti-wear) or R&O (rust-and-oxidation-inhibited) oils are considered critical well below AN 3. Working with your oil supplier’s engineering department and/or a reputable oil lab with experience in your industry is the best way to set up meaningful acceptable limits for your environment.

A change in oil’s acidity (TAN) points to base oil deterioration, oxidization, and contamination.

Additive Elements. The table on p. 38 lists the typical standard elements for which oil analysis tests. Since some perform in multiple functions, they must be checked against a virgin sample and operational profile to determine if they are beneficial or detrimental when their values are compared with known values.

Fluid-contamination testing

Dirt, water, and chemical contaminants are highly destructive to lubricants. For the most part, however, they’re easily avoidable.

Solids contamination. Testing for solid contaminants involves particle counting based on ISO Cleanliness Code ISO 4406:1999. One method requires a technician to use a light microscope and manually count the number of particulates in a 100-ml oil sample that are >4 microns, >6 microns, and >14 microns in size. The total is then compared with the ISO 4406 cleanliness chart to derive a three-number ISO cleanliness rating. An alternative, automated approach leverages sensors and light-absorption principles to detect and count particles. With this method, ISO 4406 calls for three sample size counts at >4 microns, >6 microns, and >14 microns.

Water contamination. Water in oil promotes rust and corrosion—and, in a dissolved state, will accelerate oxidation. Water can be introduced as contamination through wash downs of equipment or leakage. Prevention measures include coalescing filters/breathers and physical waterproof protection around areas susceptible to moisture ingression.

Testing for water contamination typically involves the Karl Fischer moisture titration method: A vaporized oil sample is carried by oxygen-free nitrogen into a reaction-vessel containing methanol. Trapped moisture is titrated to an end point with a reagent to establish the presence of water in parts per million.

Beyond why and what

The procedures discussed here represent the major components in standard, inexpensive oil-analysis testing. In most cases, they’ll indicate when to change oil, based on condition. Unusual or inconclusive findings should generate more-specific testing that can lead to positive outcomes for both lubricant and machine. MT

Ken Bannister is managing partner and principal consultant for EngTech Industries Inc., Innerkip, Ontario, an asset management-consulting firm now specializing in the implementation of certifiable ISO 55001 lubrication-management programs and asset-management systems. For further details, telephone 519-469-9173, or email kbannister@engtechindustries.com.

 

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