Archive | Contamination Control

59

9:57 pm
June 13, 2016
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Six Lubrication Myths Debunked

When it comes to machinery health, some lubrication myths are downright dangerous.

When it comes to machinery health, some lubrication myths are downright dangerous.

Despite years of concerted efforts by industry experts and suppliers, some dangerous lubrication myths continue to swirl around many maintenance operations. Motion Industries lubrication specialist Chris Kniestedt takes a down-and-dirty approach to debunk six of them.

Myth 1: All lubricating oils are the same.

From hydraulic fluids to gear lubricants to motor oils, each lubricant, be it synthetic or mineral-based, is uniquely formulated for its application with a specific viscosity; additive package; physical, chemical, and performance properties; and regulatory requirements. Various products may or may not be compatible with each other (see Myth 6).

Myth 2: If a little is good, more is better.

Take grease, for example. Over-greased bearings are a major cause of equipment failure. Blown seals and overheating are just two negative results of using too much grease. A general rule of thumb for normal- or high-speed machinery is that it’s better to err on the side of caution and to always check the OEM’s recommendations.

Overfilling gearboxes will also lead to problems, including failed shaft seals or increased operating temperatures. A gearbox that has too much oil will have to work harder to move through the lubricant, subsequently generating more heat or churning the oil into foam.

Myth 3: Blue, red, or black grease is better than white or clear grease.

Color is not a key factor in selecting grease for an application. There’s no standard for doing so. Instead, pay attention to base-oil viscosity (based on speed, load, and expected operating temperature), thickener type to mitigate incompatibility issues and consistency, and/or how well a product will pump at operating temperatures.

Myth 4: Tacky and stringy greases and oils offer better protection than non-tacky products.

It’s important to understand that lubricants are only 10- to 20-microns thick at the point of contact. Moreover, film thickness is a function of base-oil viscosity at operating temperature and speed (to a lesser degree, load). Thus, always use caution when applying tacky lubricants or greases with higher percentages of thickener at high operating speeds.

Myth 5: Food Grade (NSF H-1) products are never as good as Non-Food Grade (NSF H-2) products.

Advances in base-oil technology and additive chemistry have made Food Grade H1 products stronger than ever, particularly with synthetics. There are many applications where a correct, strong Food Grade H1 product will work as well as a non-Food Grade H2 mineral-oil-based equivalent.

Myth 6: All products are compatible.

Consider greases. In addition to their base oils and additive packages, greases are formulated with various thickeners (lithium, lithium complex, aluminum complex, calcium, polyurea, bentone, and silica gel), which aren’t necessarily compatible with each other. Always exercise caution when changing greases. Laboratory compatibility testing will clear up any doubts. If incompatibility exists between old and new products, purge bearings before changing to the new one. Oils aren’t always compatible either, especially with the new generation of synthetics. Finally, mixing Food Grade H1 lubricants with Non-Food Grade H2 will create contamination issues, which will cause you to lose H1 designation. MT

Chris Kniestedt is lubrication specialist for the San Francisco Division of Birmingham, AL-based Motion Industries. For more information visit www.motionindustries.com.

135

5:03 pm
June 13, 2016
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The Color of Lubrication

Add visual management to your lube-program toolbox through an array of color-coded solutions.

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

When you hear the word lubrication, what color comes to mind? If you answer brown, or allude to some shade of it, you’re in good company. More than 80% of maintainers to whom I’ve posed this question over the past 30 years have responded the same way.

The reality is that oil and grease products come in a rainbow of colors and shades, including white, gray, black, silver, blue, green, red, purple, and every variation of brown, from golden honey to dark, earth tones. Manufacturers typically color these products for their own purposes. Unfortunately, there’s no formal industry standard or convention regarding their choices, with the exception that most food-grade greases tend to be white.

Most lubricant colors are naturally influenced by the color of the crude base-oil stock and its additive package. For example, when molybdenum disulphide (MoS2) is added in any quantity, it can significantly darken the lubricant to near black in color. Manufacturers, though, add colorants to their respective lubricants to help identify different brands and/or make products more appealing and marketable to the end user.

Despite incongruent colorization, maintenance departments can take advantage of differences in lubricant colors in their plants. For example, if two or more grease brands or different colors are employed in a facility, personnel can be made aware of which color belongs to what bearing by a photo of that grease color posted on the machine or close to the grease nipple. If a trace amount of the previously used grease is evident at the bearing or grease nipple, maintainers would (should be made to) understand that they are not to pump a grease of a different color or shade on top of the original grease.

Oil colors are a different matter. Oil ages in service and its additive package will deplete through contamination, heat, and oxidation. This causes a natural darkening in color. That visual cue has been used for many years in industry and the automotive world to manage oil changes. Sadly, this somewhat risky strategy can fall flat when an oil is changed out with one of a different color and additive composition—especially in the case of darker oils.

Introducing color coding

In 1950, the prestigious UK Scientific Lubrication Journal published an article by M.J. Harrison titled “Color Codes.” In it, Harrison, who at the time was an engineer in the technical department of the UK’s C.C. Wakefield & Co. (now known as Castrol), detailed a symbol/color-control system methodology for identifying the lubricants used in an industrial plant. As he pointed out, employing symbols to denote frequency of application and colors to signify lubricant type would ensure that unskilled workers were able to perform “factory lubrication” in a consistent manner, with scientific precision.

Harrison went on to recommend the use of different 1-in.-high geometric symbols painted on lubricant reservoirs or at lube points to represent lubrication-interval schedules. He proposed a circle to represent the need for daily lubrication, a triangle for weekly lubrication, and a square to represent monthly intervals between lubrication activities. For activities conducted on a quarterly basis (or over longer periods), the square was to again be used, but this time with a number painted inside the square to highlight the number of interval months.

To determine the correct lubricant to apply, each symbol was to be painted one of three primary colors: yellow, red, or blue to correspond with an already-determined lubricant legend. If more than three lubricants were to be used, the same colors were used again, but with the addition of a bold black diagonal stripe across the symbol.

But Harrison didn’t stop with the design and color of symbols and shapes to help identify different lubricant and application intervals in a facility. He also advocated color-coding reservoirs and dedicated transfer equipment to eliminate cross-contamination problems.

Which colors to use

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Color identification is an ideal means of ensuring that the right lubricant ends up in the right place, at the right time. The actual colors themselves are not as important as their consistent use, i.e., assigning a specific color to a single lubricant and all dedicated equipment employed in its use, storage, and transfer within the plant environment, as depicted in Fig. 1.

Fig. 2. This yellow-color-coded, transfer container is from OilSafe, Rockwall, TX (oilsafe.com).

Fig. 2. This yellow-color-coded, transfer container is from OilSafe, Rockwall, TX (oilsafe.com).

Harrison initially promoted the three primary colors of red, blue, and yellow for his system. In modern plant environments, however, we’re comfortable using primary and secondary color palettes, including green, orange, and purple. This is clearly evidenced by the breadth of today’s commercially available, color-coded lubrication-handling systems, including the example transfer products shown in Figs. 2 and 3.

Fig. 3. Shown is an orange-color-coded, clear-body, pistol-grip grease gun from OilSafe, Rockwall, TX (oilsafe.com).

Fig. 3. Shown is an orange-color-coded, clear-body, pistol-grip grease gun from OilSafe, Rockwall, TX (oilsafe.com).

Lubricant storage and transfer systems, though, reflect just one area where colorization pays off for a site. Another important use of color identification involves a condition-based approach to filling oil reservoirs.

Fig. 4. Color-coding is used on this condition-based Hi–Lo lubricant-reservoir-fill application. (courtesy EngTech Industries Inc.)

Fig. 4. Color-coding is used on this condition-based Hi–Lo lubricant-reservoir-fill application. (courtesy EngTech Industries Inc.)

Figure 4 is a good example of this Hi-Lo technique. It involves using red, amber (yellow), and green lines taped on the side of an automated-lubrication-system reservoir. This arrangement is known as a RAG (red/amber/green), or the traffic-light indicator system:

  • The green line indicates the upper fill level.
  • The amber (yellow) line indicates a level at which the operator is to contact the maintenance department with a first request to fill the reservoir.
  • The red line alerts the operator to call in a priority request to fill the reservoir.

Coloring your efforts

Today, you’ll find an array of color-coded tags and transfer equipment in the marketplace. These types of innovative solutions are relatively inexpensive to purchase and implement—and highly effective when used consistently. The question is, “Just how colorful are your lubrication efforts?”  MT

Ken Bannister is managing partner and principal consultant for EngTech Industries Inc., (Innerkip, Ontario, Canada), 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.

learnmore2— Industrial Lubrication Fundamentals: Storage & Handling

— Handling, Storing and Dispensing Industrial Lubricants

Key Factors in A World-Class Lubrication Program

The Five Rights of Lubrication

365

5:28 pm
January 12, 2016
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Lubrication Strategies: Several Hands Responsible For This Oil Debacle

The actions of personnel can either lead to great success in lubrication programs or, as this case study shows, to costly calamity.

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

Lubrication team members must understand how their actions can have negative upstream and/or downstream impact should they neglect to effectively and efficiently fulfill their roles.

Lubrication team members must understand how their actions can have negative upstream and/or downstream impact should they neglect to effectively and efficiently fulfill their roles.

Winston Churchill wrote, “Responsibility is the price of greatness.” These words have special meaning for those of us in the lubrication field.

In organizations that seek to become great, all personnel must understand the negative upstream and/or downstream impact that their individual actions could have should they neglect to effectively and efficiently fulfill their roles. This is especially true of lubrication team members, who, through daily interaction with machinery and moving parts, are directly responsible for the successful lubrication of equipment in their charge—as well as for any consequences resulting from their activities. Their failures will manifest directly in the loss of equipment availability, reliability, and life-cycle longevity, and indirectly through production yield and quality losses.

A case in point

My look into the oil and grease purchasing patterns of a major North American automotive-assembly manufacturer during a lubrication-operations effectiveness review (LOER) was a real eye opener. I was astounded by the many tens of thousands of dollars per month the corporation was spending on just one type of chain-lubricant oil.

This automatic-chain-lubricator oil was a name brand, premium-quality, molybdenum disulphide, high-temperature formulation. Designed specifically to lubricate power- and free-conveyor chain pins and bearings passing through the types of high-temperature paint-bake ovens found in automobile assembly lines, it was an ideal match for the application. So, given those facts, why was the facility using so much of the product for just four conveyor-lubricator systems? Moreover, why had the lubrication staff or the lubricant supplier neither noticed nor brought to management’s attention the systems’ dramatic (more than 10-fold) increase in lubricant consumption over the past two years?

Further investigation revealed that the chain-oil consumption increase had coincided with the hiring of a new lubrication technician. The PM (preventive maintenance) job plan and frequency for checking and filling the automated lubricator reservoirs, though, had remained unchanged—from the time the devices were installed and commissioned more than three years prior. This discovery prompted a physical investigation of the four lubricators themselves. The findings were more than surprising!

The four lubricators were a popular, highly reliable brand. Low-tech in design, they used a pneumatic pump-to-point-style pump connected to dynamic injectors that would “volley” or “shoot” a small fixed amount of oil into either the unshielded trolley rolling-element bearings or the chain-link pins that connected the trolleys.

All of the devices were in excellent condition—and still located where they had been originally installed—complete with reservoirs full of oil. Curiously, though, all had been shut off electrically at the breaker and their pneumatic air supplies had been shut off at the feed-line valves. As a result, all of these units were totally useless.

Investigators subsequently learned that the four original lubricators had been “replaced” further down the conveyor line by a makeshift gravity-lubrication system that featured 1-gal. paint cans clamped to the conveyor I-beam as oil reservoirs. Installed in the bottom of each can were two small cock valves fitted with copper lines dropping down to two commercial, adjustable oil-drip brushes that were very wet with lubricant—just like the over-lubricated conveyor chain and roller bearings they served.

Questioned about this state of affairs, the plant’s production and quality supervisors told a story of numerous paint-quality problems that, they believed, had been caused by lubricant over-spray. After complaining about the matter to the new lubricant technician, they said, the situation eventually seemed to improve, i.e., fewer quality incidents occurred.

When interviewed, the lubrication technician reported that upon assuming his new role he had received no formal training or direction other than to follow the instructions on the work orders and use common sense. Shortly after starting the job, because of the workload, he decided to ignore the automated lubricator PM work order and, instead, rely on the lubricator-reservoirs’ low-level lights as condition indicators for adding oil. After the first three months, all low-level indicators had activated, at which time the technician had correctly filled the reservoirs with the correct oil (or so he thought).

During later lubricant checks, however, the reservoirs appeared full, and didn’t seem to be dispensing oil at all. Consequently, after multiple unsuccessful attempts to alert his supervisor to the situation, the technician took it upon himself to exercise his personal version of common sense and engineer a new system. Thus was born the gravity system of paint cans and brushes—for which, incidentally, almost a year had been spent working out the settings so that oil wouldn’t drip off the conveyor on to the painted vehicles. (To his credit, the technician did show the new system to the lubricant supplier’s representative. Accordingly, after approving the design, the rep also began enjoying increased orders and commissions for his product.)

In the end, simple diagnostics performed on the automated chain-oil lubricators found the units to be in perfect working order. The reason they had failed to dispense lubricant? At some point, their oil levels had been allowed to drop so low that the injectors and pumps lost their prime. The devices simply needed to be re-primed.

Lessons learned

As this case study shows, a few simple lapses in responsible behavior resulted in serious quality issues requiring many hundreds of thousands of dollars in vehicle repaint costs, many tens of thousands of dollars in excess lubricant costs, and overall reduced conveyor life due to ineffective lubrication practices.

Many readers might vote to place blame wholly on the lubricant technician for this calamity. In this story, though, he should only take partial blame: A millwright by trade, with no formal lubrication training, he had been placed in his position based solely on seniority. To exacerbate the situation, there were no specific priming instructions regarding the automated lubricators, either in the work-order job plan or on or near the units themselves.

Still, while the technician tried unsuccessfully, on several occasions, to notify his supervisor of the lubricator problem, he also chose to ignore the initial PM in favor of a different lubrication approach without performing a risk analysis. His McGyver-style paint-can fix could definitely be construed as irresponsible for a tradesperson. He should, at the very least, have tried to find an operations manual or learn more about the specific lubricators he was dealing with before condemning them so quickly and creating a bigger downstream problem.

Much of the blame, however, really belongs to the site’s supervisory personnel:

  • the maintenance supervisor who irresponsibly did not adequately support his technician or notice the makeshift lubricators and/or the massive increases in his monthly lubricant spend
  • the production supervisor who irresponsibly bypassed the maintenance supervisor in favor of speaking directly to the lubrication technician.

Final blame goes to the irresponsible actions of the lubricant supplier. From an ethical standpoint, its representative certainly should have discussed the massive increase in chain-oil consumption with the plant’s maintenance supervisor and/or the purchasing department.

Responsibility is born out of knowing what to do and when to do it. In the case of the four referenced automated chain lubricators, problems could have been prevented with:

  • lubrication certification training
  • clear workflow processes
  • improved PM work-order job plans
  • standardized operating procedures
  • failure risk analysis on critical equipment
  • improved inter- and intra-departmental communications.

To be sure, the lubrication technician in this story was out of his depth. With a little effort, however, the costly scenario that he created could have been avoided.  MT

Lubrication expert Ken Bannister is principal consultant with EngTech Industries, Innerkip, Ontario. He is the author of Lubrication for Industry and the Lubrication Section of the 28th Edition of Machinery’s Handbook (both Industrial Press, South Norwalk, CT), contact him at kbannister@engtechindustries.com.

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“Extending Chain Life”

“Key Factors in a World-Class Lubrication Program”

“Keep Hydraulic Fluids Contaminant Free ”

637

7:04 pm
August 6, 2015
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Keep Hydraulic Fluids Contaminant Free

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Understanding how contaminants enter a hydraulic system is key to development of an effective maintenance strategy.

Hydraulic systems rely on vital fluids to transfer and amplify power and lubricate critical components. Protecting those fluids from contamination should be a top priority.

By Ken Bannister, CMRP, MLE, Contributing Editor

Despite their complexity, hydraulic systems are very forgiving beasts—almost too forgiving for their own good. They’ll tend to perform inefficiently for a long time before catastrophic failure occurs. Unfortunately, this forgiving nature can foster a widespread, apathetic approach toward failure prevention, efficiency optimization, and service life-cycle management. Fluid is the most important part of any hydraulic system and when systems fail, the cause is most often related to fluid/fluid contamination. Those failures usually take other critical equipment and processes with them.

Exorcise the “big three”

Hydraulic-fluid contamination comes in three major forms: solid particulate, water, and air. All of these can seriously affect the fluid and the equipment components it serves. Maintaining hydraulic fluids in optimum condition requires measuring, controlling, and preventing the introduction of these contaminants. Since contamination in any form can be inherent and induced, understanding how the three types enter a system is important in developing effective preventive-maintenance (PM) strategies. 

Solid-particulate contamination. Hydraulic system components are designed to operate with tolerances that can be as close as 1.5 microns. Solid particulate most often manifests itself as grit or dirt that, if allowed into a system, can be extremely damaging to bearing surfaces and hydraulic seals. The solid particles, which can be more than 100 microns in size, will set up in a three-body abrasion state and easily score the mated machined surfaces, creating rapid bearing and component-surface wear, leading to unwanted fluid bypass that reduces operating efficiency. Solids contamination will also cause valve stiction, increased fluid viscosity, and unwanted fluid leakage through nicked and scored cylinder seals.

If your equipment is new or rebuilt, solids contamination in the form of leftover dirt or swarf from the manufacturing/rebuild process could be present in the hydraulic lines. Prior to initial startup, lines should be wad cleaned, existing oil flushed from the system, and new, correct-viscosity fluid added.

Many end-users are unaware that solids-contamination levels can be excessive in new oil supplied from the manufacturer or introduced by the supplier if bulk-transferred through dirty transfer hoses and equipment. When receiving new—especially bulk—oil, always perform an oil analysis to detect solids and water contamination.

While new oil can often be found at a 19/17/14 cleanliness level on the ISO solid-contamination code, that’s not clean enough for high-pressure hydraulic systems.  These systems require fluids with a minimum 16/14/11 cleanliness level. To protect your site’s hydraulic systems, establish a cleanliness contract with your oil supplier who will then be bound to provide proof of cleanliness upon delivery.

Other sources of solids contamination, all of which are preventable, include:

  • improperly stored oil
  • dirty equipment used to transfer the oil into the equipment reservoir
  • reuse of dirty “leaked” oil
  • “open to air” reservoirs due to missing fill ports or reservoir breathers
  • lack of filter maintenance, causing dirty oil to bypass into the system
  • poor housekeeping practices. 

Water contamination. Water, a universal contaminant, will saturate hydraulic fluid at a mere 300 ppm or 0.04% concentration level. It can be present in:

  • a free state, separated from the fluid in an unstable form
  • an emulsified state, in a stable form that appears cloudy
  • a saturated, dissolved form that appears invisible.

Water depletes vital oil additives or, even worse, reacts with additives to create corrosive acids that attack system components. It can also reduce a lubricant’s film strength and its ability to release air, which can increase wear, corrosion, and cavitation.

Some hydraulic fluids—such as brake fluids—are designed to be hygroscopic and entrain moisture in the fluid until its saturation point is reached. In high-heat applications, water can boil off and create great inefficiency in the hydraulic power-transfer motion. 

Typical water-contamination sources include:   

  • incorrect outdoor lubricant storage practices that cause hot-cold cycle condensation
  • “open to air” reservoirs into which washdown and/or process water can splash/spill.
  • In most instances, water can be detected visually in its free and emulsified state. To remove water contaminants use:
  • polymeric-style filtration media designed to absorb the water as it passes through a filter
  • vacuum distillation to boil off the oil
  • dehumidification in the reservoir headspace.

Air contamination. This type of contamination presents in a number of forms, of which entrained air can be the most problematic. In this form, air bubbles (<1 mm dia.), dispersed throughout the fluid, reduce viscosity and, thus, film strength. This situation, in turn, can cause premature component wear; a reduction in the oil’s bulk modulus, causing a lack of efficiency and control due to the sponginess of the oil condition; an increased heat load, leading to fluid deterioration; and system erosion, due to cavitation.

Air bubbles greater than 1-mm dia. create foam, which can quickly deplete any antifoam additive and cause fluid oxidization.

Typical causes of air contamination include:

  • over-/under-filled lubricant reservoirs
  • clogged inlet/suction filters
  • clogged reservoir breathers
  • restricted inlet lines
  • loosely clamped inlet lines
  • pump-shaft seal failures.

Prevention control

Fortunately, the contamination problems discussed here are easily preventable—in most cases at minimal cost. While the following advice is not all-inclusive, this list provides an excellent starting point for a successful hydraulic-fluid PM strategy:

  • Implement a fluid cleanliness standard.
  • Store all lubricants in a cool, dry place and practice FIFO (first in-first out) stock rotation.
  • Practice good housekeeping, ensuring that reservoirs are clean of dirt and debris.
  • Cap all system hoses and manifolds during fluid-handling and system maintenance.
  • Wad-clean all lines prior to initial system startup.
  • Flush all lube systems and change oil, prior to startup.
  • Use a dedicated filter cart for each hydraulic-fluid type, with quick-connect fittings to transfer/clean hydraulic fluid before it enters a reservoir.
  • Install external sight gauges marked with high- and low-level marks in reservoirs to check for fluid levels and the presence of water.
  • Use polymeric oil filters and desiccant reservoir air breathers.
  • Specify rod wipers and replace all worn actuator seals.

With a little care and common sense, your plant’s hydraulic systems—and the vital fluids that keep them up and running—will be efficient, reliable, and long-lived. MT

Contributing editor Ken Bannister is a Certified Maintenance and Reliability Professional and certified Machinery Lubrication Engineer (Canada). The author of  Lubrication for Industry (Industrial Press, South Norwalk, CT) and the Lubrication Section of the 28th Edition of Machinery’s Handbook.(Industrial Press), he can be reached at kbannister@engtechindustries.com.

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— National Fluid Power Association
— 
International Organization for Standardization
— 
Society of Tribologists and Lubrication Engineers

851

7:34 pm
July 8, 2015
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Lubrication Strategies: Beware Grease Incompatibilities

When two incompatible greases are mixed, either deliberately or accidentally, the results can be disappointing, if not devastating.

By Jane Alexander, Managing Editor

The problems associated with grease incompatibility manifest themselves in various ways. According to bearing manufacturer NSK Americas, Ann Arbor, MI, scenarios include:

  • A lab technician tests grease from a problem bearing and finds that, while it meets all specifications, it doesn’t perform as it should.
  • A mill switches grease based on glowing reports from other facilities, then finds the new product doesn’t deliver the promised results.
  • A critical plant motor fails during rush production, despite having been lubricated as specified in the maintenance manual.

In each case, NSK representatives said, these sites had changed from one type of grease that met specifications to another type, which also met specs. They all fell victim to grease incompatibility.

Although maintenance organizations should be well aware of this information, not everyone remembers that some greases can’t be mixed with other greases—even when both types meet specifications. Unless incompatibility is understood and accounted for, switching grease can be catastrophic.

The table shows the results of compatibility tests on 10 different types of grease. The“worked penetration test” was used because it is rapid and reliable. Each tested grease proved to be incompatible with at least one other grease. Courtesy NSK Americas.

The table shows the results of compatibility tests on 10 different types of grease. The“worked penetration test” was used because it is rapid and reliable. Each tested grease proved to be incompatible with at least one other grease. Courtesy NSK Americas.2

Defining ‘incompatible’

Incompatibility occurs when a mixture of two greases shows properties or performance significantly inferior to those of either grease before mixing. Some grease bases are intrinsically incompatible. Different fatty acids and/or additive packages also affect compatibility. To make things even more confusing, sometimes two types of greases that are manufactured as a mixed-base product are incompatible when mixed in operation.

Unfortunately, issues associated with grease incompatibility usually aren’t apparent until the bearing is in use. At that point, major problems can develop. Thus, it’s best to know in advance which types of greases can be used together and which can’t (see table).

Make grease changes safely

What if switching grease is necessary? Several steps ensure safe changeovers. The good news is that incompatible greases don’t have to be eliminated completely. Preparing carefully and paying close attention to details can prevent problems:

  • Ask your lubricant supplier(s) about product compatibility.
  • Use up as much of the old grease as possible before introducing the new grease into the system. The ideal course of action is to completely drain and clean the system before changing over.
  • Once the new product is added, grease flow should be increased temporarily. This will move the interface (the area of grease mixing) through and out of the system as quickly as possible. The increased flow also assures good lubrication and proper sealing while overly soft grease may be in the bearings.
  • When in doubt, expect incompatibility and watch for problems. MT
Learn More

NSK Americas

National Lubricating Grease Institute

857

6:37 pm
June 12, 2015
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Lubrication Checkup: Oil “Lumps” Blocking Injectors

1014lubecheckupBy Ken “Dr. Lube” Bannister

Symptom

We have experienced lubricant-injector failures in a number of our conveyor lubricators. We’ve used the same brand of high-temperature chain oil for the past five years without issue, except for the last drum. In that drum, we discovered coagulated “lumps” floating in the oil. The oil supplier is blaming our storage practices. Meanwhile, we’re having great difficulty getting the lubricators to work, despite changing the oil for fresh product. Any suggestions?

Diagnosis

Regarding lubricant condition, oil has a shelf life determined by base-oil type, additive-package ingredients, and the finished product’s storage prior to use. Most lubricating-oil manufacturers claim an estimated shelf life of +/-5 years when their products are stored correctly indoors. Wide temperature swings, however, can result in wax and sediment creation (if the oil gets too cold), premature oxidation (if it gets too hot), and condensation-moisture contamination from hot/cold temperature cycling. Interestingly, high-temperature lubricants can be manufactured with volatile carrier agents that can flash off during storage (especially if open to air) and cause the remaining lube to “thicken” or coagulate.

Regarding your lubricators, injector-style conveyor designs require priming on the lubricator’s initial fill or when the lubricant level falls below the pick-up tube point. Badly contaminated or coagulated lubricants can make the injector difficult or impossible to prime.

Prescription

  • Always check with your supplier about the shelf life of your lubricant(s) and develop a purchase-quantity and stock-rotation strategy based on first in/first out principles and current usage patterns. To promote freshness, buy small amounts on a frequent basis and always use an indelible marker to note the receipt date on lubricant containers when they are delivered.
  • Never store new containers of lubricant outdoors without protection from the elements. If possible, strive to store all oils and greases in a dry, indoor location at a temperature range between 0 and 110 F.
  • Ensure that all lubricant-container bungs, lids, and breathers are always in place.
  • Use a suitable cleaning or flushing agent to remove old oil from your lubricators, pumps included.
  • Finally, remove and replace injectors with new ones of the same size, then prime the lubricator with fresh oil, according to the manufacturer’s instructions.
  • Proper storage will go a long way toward achieving specified lubricant performance. MT

Ken Bannister of Engtech Industries Inc., is a lubrication management specialist and author of Lubrication for Industry (Industrial Press), and the Lubrication section of the 28th Edition Machinery’s Handbook (Industrial Press). For in-house ICML lubrication-certification training, contact him at 519-469-9173 or kbannister@engtechindustries.com.

2458

6:54 pm
September 28, 2014
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Detection Of Cooling-Water Intrusion Into Standby-Power Diesel Engines

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This case study discusses pitfalls associated with the condition-monitoring of oil in a generator’s lubrication system.

By Randall Noon, P.E.

Diesel-engine generators, the stalwart mainstays of standby-power systems, offer several advantages: They efficiently provide electrical power, when needed, with the push of a button or automatically, perhaps, when under-voltage conditions in the grid trip their start relays. Also, the handling and storage of diesel fuel presents fewer safety concerns than gasoline or natural gas. And finally, an on-site storage tank full of diesel fuel offers more reassurance in a crisis than pipeline-supplied natural gas, which could be disrupted by an earthquake, flood or other extreme event.

Despite their robust natures and practical attributes, however, diesel-engine generators require certain levels of care and predictive/preventive maintenance—especially units that function in a standby capacity. Discovering in the middle of a power blackout that a site’s critical standby-power system won’t run is a high-stress headache no maintenance department needs. Allowing water to enter undetected and wreck havoc in these units’ lubrication systems is a sure way to induce that type of headache.

Cooling-water intrusion into the lubrication system often results from a faulty gasket around a cylinder head, a cracked cylinder liner, a warped head or uneven bolting of the cylinder head to the engine frame. In any case, water in the engine oil is undesirable. Such intrusion can have a significant impact on the unit’s ability to run: If enough moisture has entered the lubrication system, water carried by the oil may evaporate during the combustion cycle and leave dry spots that allow the piston and cylinder walls to make metal-to-metal contact. This usually results in damage to the cylinder, the liner and the engine. Continued operation of equipment with this condition will damage the unit and can lead to complete engine failure. With that in mind, consider the following example from the real world.

Uncovering the problem

In a routine test run of a standby 5000 KW, 16-cylinder diesel-engine generator unit, water was observed in a lubrication-oil sight glass. Subsequent investigation discovered a jacket-water leak in the 1-left cylinder.

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During troubleshooting, the water jacket was pressurized to 11 psig, and water began running off the piston on the interior of the cylinder liner. The fuel injector was then removed and a bore scope employed to examine the internal area. As shown in Fig. 1, the liner was found to be leaking from a point about one inch below the piston-ring reversal area and filling the top of the piston. Subsequent examination indicated that the liner had cracked.

As with many units, the water jacket had an automatic refill feature. When the coolant level in the engine-water jacket drops, cooling water is automatically replaced in the standpipe by a level-control device. Given this arrangement, if a leak were to occur in the water jacket, any “missing” water would not be noticed. Consequently, attempting to determine when the liner crack started by checking for “missing” coolant was a dead end.

The coolant consisted of demineralized water with an added corrosion inhibitor: sodium nitrite. Since coolant leaking into the lubrication system would also carry with it sodium nitrite in solution, the presence of this corrosion inhibitor in the oil was used as a marker to indicate when cracking in the liner had sufficiently developed to allow coolant intrusion into the oil. The engine oil was regularly tested, and one of the tests looked for sodium content.

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A review of oil-analysis reports showed that on the day of the engine test during which water was observed in the sight glass, the sodium content of the oil exceeded 15 parts per million (ppm)—which was the trending alert level. The sodium content of the oil versus time, as reported in oil analyses, was then plotted as shown in Fig. 2. Since the oil was sampled at quarterly intervals, the resulting plot appears choppy. The plot in Fig. 2 is further complicated by the fact that the oil had been changed several times during the period of the plot. Each oil change would, of course, knock the concentration of sodium back to zero. Despite this complication, interpretation of the plot in Fig. 2 suggests that leakage had likely begun two years earlier.

Since the concentration of the sodium nitrate in the jacket-cooling water and the sodium content in the oil were known, it was possible to estimate the amount of water that had crossed into the lubrication system. This was then compared to the amount of water that had layered out in the bottom of the lubrication reservoir and that remaining in solution in the oil.

When these evaluations were done, the estimate of water carryover through the liner crack matched the total amount of water that had both layered out and remained in solution. This finding further corroborated that the origin of the sodium was the jacket water—and not any other source. The use of the sodium concentration data depicted in Fig. 2 also allowed rough estimates of leakage rates when engine operating time and oil replacements were considered.

While a laboratory report for an oil sample taken prior to the engine-test run had indicated a sodium content of 18 ppm, it also indicated nil for water content. Water content for the previous six summary laboratory reports also indicated nil with respect to water content. These findings begged the question: If water had been leaking into the lubrication oil long before the test run, why didn’t the previous laboratory reports pick it up? Answer: Because the previous reports had indicated “nil” water, the significance of the sodium noted in previous reports was overlooked. To better understand this chain of events, keep in mind that water can be present in lubrication oil in one, two or three forms: 1) in solution; 2) in an emulsion; 3) as free water.

If not otherwise already saturated, oil is able to take a certain amount of water into solution. In this condition, it will look clear and cause minimal problems in lubricated equipment. If, however, oil has taken into solution all the water it can—i.e., when it is saturated—any excess moisture is held in suspension or emulsion. In this condition, it looks cloudy. If more water is added, the oil and water will separate into two layers. Because water is heavier than most lubricating oils, excess water will sink to the bottom. This is “free” water.

To get a sense of the amounts of water associated with these three forms of water, consider the following:

  • A saturation level of a mineral oil might be about 100 ppm, and the amount of water it can hold in emulsified form could be as much as 1000 ppm. Free water occurs when the concentration is greater than 1000 ppm.
  • Similarly, an ester-based hydraulic fluid could have a saturation level of more than 2000 ppm, and also might be able to hold as much as 5000 ppm in emulsified form. Water in excess of 5000 ppm would then form a free water layer under the oil.
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Fig. 3. Representative Chart of Water Solubility in Oil (Source: “Factors Affecting Water Solubility in Oils,” by Senja Paasimaa, Application Manager, Vaisala, [sensorland.com/HowPage073.html])

The amount of water that can be taken into solution also depends on oil temperature (as shown by the graph in Fig. 3). Oil at a higher temperature generally can take more water into solution than oil at a lower temperature. (The lubrication oil in the referenced diesel-engine generator unit is maintained at a “ready to run” temperature no lower than 104 F and no higher than 185 F.)

In this case, the water content of the lubrication oil was checked using the “Crackle Test.” This procedure involves putting two drops of oil on a hot, flat surface (about 130 C) and documenting any bubbling or “crackling” (the sound a sample sometimes makes during this type of test). The size of the bubbles is then used to indicate the amount of water in the oil. For example:

  • If no change is observed in the two drops of oil on the hot surface, it can be concluded that no free or emulsified water is present.
  • If very small bubbles (about 0.5 mm in diameter) appear, then disappear, the water content can be estimated at 500 to 1000 ppm.
  • If bubbles of about 2 mm appear, move to the center of the hot plate, increase in size to 4 mm, then disappear, the water content can be estimated at 1000 to 2000 ppm.
  • If bubbles of about 2 to 3 mm appear, increase in size to 4 mm and the process repeats with possible violent bubbling and audible cracking (hence, the test’s name), the water content is more than 2000 ppm.
  • The following limitations to the Crackle Test, however, are crucial to the discussion of this case study:
  • The method is approximate and not considered quantitative. It simply provides a rough indication.
  • If the hot-plate temperature is above 130 C, the heat can induce rapid scintillation that may not be detected by the observer.
  • The method provides no information about the amount of water in solution in the oil.

Developing new best practices

Based on the limitations of the Crackle Test and the data in Fig. 3, it became clear to the site’s maintenance department that water content could “hide out” in solution within the oil of a generator’s lubrication system. This situation had gone undetected over time because oil samples were usually taken right after a test run, when the lubrication oil was still hot (higher temperature => more water in solution).

In short, to proactively detect engine-cooling-water intrusion into the lubrication oil system before it affects the readiness of this site’s standby-power equipment, the amount of oil in solution must be monitored along with the amount of sodium detected in the oil.

Furthermore, personnel now understand that before the standby unit’s lubrication oil is changed—or fresh oil is added—samples of the existing oil must be evaluated. This way, any increase in sodium or water in solution can be compared to where it left off the last time.

Randy Noon is a Root Cause Team Leader at Nebraska’s Cooper Nuclear Station. A Registered Professional Engineer, book author and frequent contributor to Maintenance Technology, he has been investigating failures for more than three decades. Contact him at rknoon@nppd.com.

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8:47 pm
June 19, 2014
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Des-Case Acquires ESCO Oil Sight Glass Portfolio

3-D BullsEye Des-CaseNashville, TN-based Des-Case Corp. has purchased the visual-oil-analysis line of  ESCO Products, Inc., the well-known Texas manufacturer of oil sight glasses and level-monitoring technologies and distributor of Copaltite and Dow Corning products. The acquired portfolio includes ESCO’s 3-D BullsEye Viewport, oil sight glasses, indicators and level monitors.

Headquartered in Houston, family owned and operated ESCO has been in business for nearly 50 years. Its visual-oil-analysis product line began over 30 years ago with the introduction of the Esco Oil Sight Glass (OSG). In the years since, that first OSG design has been modified and the line expanded to include horizontal, high-temperature, large-volume and level-monitor models. The contamination-detection capabilities of these products appear to be an ideal fit with Des-Case’s breathers, filters and other fluid-handling solutions and services that protect and clean lubricants.

According to Des-Case CEO Brian Gleason, broadening his company’s offerings with visual-detection products strengthens its position as a convenient and dependable partner for operations that want to improve their reliability and extend oil and equipment life. “Through our global distribution network and OEM partnerships,” he said, “Des-Case will expand an already-trusted product line in the marketplace to broader geographic and industry reaches.”

Commenting on the recent transaction, ESCO’s President David Haught noted that a sight glass combined with a Des-Case desiccant breather and proper filtration provides “the ultimate protection” for lubricated equipment. “Aligning with Des-Case,” he said, “offers a way to take the product line to more customers and industries than we ever could on our own. We saw it as a natural step in the products’ and our company’s growth.”

ESCO will remain a distributor of Des-Case products and oil sight glasses and will continue to sell Dow Corning products.

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