Market Topics

Healthier Lubes are in Your Grasp


Wash your hands is excellent advice for the doctor performing a medical check-up, and maybe not a bad idea for those who maintain machinery either. Just as in health care, being mindful of basic cleanliness will assure longer life for lubricants and the equipment it flows through, whether mobile or stationary.

That was the message Dan Holdmeyer of Chevron Global Lubricants brought to the Society of Tribologists & Lubrication Engineers meeting in Atlanta. A field support specialist and lubrication engineer with over 30 years experience, he gave what amounted to a master class in the risks of using contaminated lubricants, as well as the practices, ranging from simple to sophisticated, that can keep an industrial lubrication system healthy.

Particulate contamination is the Number 1 cause of lubricant-related equipment failures, he stated, and causes most serious damage to system components. The Number 2 culprit: water.

Since these twin menaces are present in some amount wherever lubricants are used, operators need to get a firm grip on both.

The cost of excluding a gram of dirt is probably about 10 percent of what it will cost you once it gets in the oil, emphasized Holdmeyer, who is based in the Cleveland area. Lubricant cleanliness starts with proper storage, handling and dispensing, he said, and continues with learning to measure and control contaminants before they can do harm. Rooting out bad habits requires time and training, but the pay-back for instilling best practices comes in reduced costs, longer critical equipment life, less downtime, lower maintenance spending, and of course reduced expenditures for new oil.

Part of the problem is getting management to agree to commit to improving, he commented. You need to lay it out in black and white for managers. A lot of people talk a good game, but then you go out in real life and see whats happening in the plant.

Heres the typical lubricant contamination cycle he has observed in the field: The equipment maker sets an ISO cleanliness standard for the lubricant (more about that later), and a lubricant product meeting that requirement gets delivered to the end user. The fluid is stored, but outdoors and in oil drums that are left unsealed or stored upright. The contents are measured using dirty dipsticks, and funneled into transfer containers which have become caked with residue or grime. The machine it goes into operates without a proper breather, so its inhaling dirt and vapor, and the fluid reservoir is uncovered too. And at each step, the contamination level keeps going up.

Best practices

To end this cycle, the first step is to store the lubricants, their pumps, containers and tools all indoors in a clean environment, Holdmeyer said. This will also reduce temperature cycling of the fluids, which hurts additive effectiveness. If stored outdoors, bulk lube containers will warm up and cool down repeatedly and result in air displacement as the fluids expand and contract – even if the containers are sealed.

Indoor storage is not always possible, of course, but weather changes will create more havoc with drums stored outside and left upright, he continued. Rainwater will collect on top of the drum, which heats up in the daytime so air escapes through the cap. Then when its cool at night, the contents contract and that vacuum draws moisture and dirt back down into the drum. Instead, always store drums on their sides, under a tarp or shelter, with caps in the 3 oclock and 9 oclock positions where water is least able to collect. At the very least, drums should be tilted so rainwater will drain away from the caps.

Far more preferable is for a manufacturing plant or maintenance facility to have a lubricants storage area or cabinet safely indoors, for drums and pails and other supplies. Holdmeyer recommends it be self-contained and fire-proof, with explosion-proof lights. It also can hold a supply of single-use disposable dispensers or well-made reusable transfer containers (he especially likes the color-coded plastic ones), clean rags and a covered waste can.

But old habits die hard, he conceded. We see makeshift dispensers and jugs used, which are left open to contami-nants, or set down into spills and other dirt. Ive also been in plants where every nozzle on every lube container has been left open for the oilers convenience. That immediately defeats their purpose.

When fluid reservoirs need to be topped up or refilled with fresh fluid, he suggested using a drum transfer cart that combines a wheeled drum dolly equipped with hoses and filters, so everything is at hand when needed for clean dispensing. Another good idea: quick connects on equipment that are sized to only take certain lubricants, so misfilling with the wrong fluid is avoided.

Which packages work?

Plants should review the lubricant packaging styles, and work to eliminate drums where possible, Holdmeyer advised, but not if your volumes are so low that you have a tote that takes a year to empty. You dont want an oversize storage tank. If a plant has the lubricant volume and turnover to make storage in tote bins practical, it should assure that all bulk lubricant deliveries meet ISO cleanliness codes, and are filtered at the time they are offloaded into the tote. A dessicant breather on the tank is also needed to reduce moisture ingress.

Sample and clean your lubricant storage tanks at least once a year to reduce water and contamination problems, he added. If not that, you need to at least flush the drain and visually inspect them.

Its important to control contamination before it gets into the system. And that means knowing the source of contamination. Is it wear debris that has been generated by the system, or is it ingress from poor storage? Is it being introduced during oil sampling, or slipping in because the oil isnt kept covered?

Its not rocket science, but we find the same things throughout industries, such as inadequate reservoir covers, he said. We see contaminants coming from routine maintenance, including from the addition of new lubricants. Whenever you pump new lubricant into a piece of equipment from a drum, you should be filtering it as it goes in.

Sensitive hydraulics

Although every lubricated component on a piece of equipment will suffer from dirt and water contamination, hydraulics seem particularly sensitive to dirt, and its most quickly noticeable, Holdmeyer said. This is because the typical clearances in hydraulic components are extremely small. Servo valves, for example, may have just 1 to 4 microns of clearance between the parts. As Holdmeyer explained, 10 microns is about the size of talcum powder, and bacteria is about 2 or 3 microns in size.

The goal is for any particles to pass freely through the equipment, so hydraulic equipment builders specify an ISO cleanliness level for the lubricants going into their equipment. This is a system for counting both the size and number of particles present in the fluid. Most OEMs suggest maximum allowable counts at three particle sizes, such as 4, 6 and 14 microns; if any count rises above a certain level, steps need to be taken immediately to clean or replace the fluid. (Some OEMs, like Caterpillar, specify just two micron sizes to be measured, not three.)

If not removed, contaminants will lead to hydraulic valve wear that leads to slow response times, jamming, stiction, surface erosion, solenoid burnout and safety-system failures, warned Holdmeyer. Cylinder wear also can be seen, especially on off-highway equipment that collects dust and dirt, and a compromised rod and seal system is a major contributor to contaminant ingression. If the cylinder rod is wet coming out of the cylinder, its time to look at it.

What about filters?

For most equipment, the first line of defense for the lubricant is going to be a filter. Citing data from Pall Corp., Holdmeyer said that with proper filtration and fluid maintenance, pumps and motors can experience a four to 10 times increase in life. Roller bearings might last as much as 50 times longer. Other savings come through less need to purchase new fluid and reduced fluid disposal costs.

Users will find every filter has a rating, but these can be misleading. If the filter has a nominal rating, its just an arbitrary value – not reproducible – and should be considered suspect, Holdmeyer asserted. What you want to look at is the filters absolute rating, which looks at the filters largest opening and what size particle can go through that filter.

Another key measurement for a filter is its beta ratio, which is the number of upstream particles of a given size divided by the same count/size found downstream in the fluid, after it has passed through the filter. For example, if the fluid upstream of the filter contains 1 million particles of a given size, and that is filtered down to just 500,000 particles, it earns a beta ratio of 50 percent efficiency. And if you can filter that 1 million particles down to 1,000, thats a 99.9 percent efficiency, related Holdmeyer.

As a general rule of thumb, he added, equipment operating at higher pressure requires increased fluid cleanliness. Increased flow controls, which amp up the valve speed and precision, also need higher fluid cleanliness levels, because the equipment tolerances are simply less forgiving of contamination. So precision roller and ball bearings, for example, usually have stricter ISO cleanliness specifications than low-speed journal bearings.

Water, water everywhere

Holdmeyer next turned to water contamination, the Number 2 cause of lubrication related failures. Just 400 ppm water can reduce bearing life by up to 85 percent of its rated life, he pointed out. Common sources of water include condensation of humid air, temperature drops, and dissolved water that condenses in storage tanks and equipment reservoirs. Clean-up hoses and wash-downs are another frequent source, as are leaks in heat exchangers and seals.

Visual inspections and lab tests can help determine the extent of water contamination in the fluid. Another way of spotting water in oil is the so-called crackle test, he said. You simply put a blowtorch on a sample of the oil and if it crackles, theres water in there.

In the field, Holdmeyer has seen many places where moisture can enter a supposedly closed circulating lubricant system. The sight-glass for checking oil level on the reservoir may be cracked or have a poor seal. Sometimes systems are not cleaned properly when the oil is drained or changed. New fluid may be added without being filtered as it goes in, so dirty make-up oil is being introduced. The system may have an air filter or old-style flap-top cap that allow it to suck in atmospheric contaminants and moisture. Instead, use a breather that filters out airborne contaminants and contains dessicants that absorb water vapor so it cant reach the fluid.

Best results require clean and dry oil, he concluded. You need to keep it clean before use, to store oil and grease properly, and apply the oil and grease in a way that maintains its cleanliness – and dont use dirty rags to wipe off fittings.

Good advice for any equipment operator whos ready to practice preventive medicine.

Related Topics

Market Topics