Industrial oil filtration
Using and maintaining the right filter for an application pays off by reducing wear and waste and by promoting energy efficiency.
By Nancy McGuire December 20, 2021
Courtesy of Dilmar Oil Co., Inc.
- Even a new oil should be filtered before putting it into a machine.
- Effective filtration is a must for newer systems that keep oil running longer, under more extreme conditions.
- Particle counters provide valuable information on how a filter performs in a specific application.
“Dirt and water are the two enemies of any kind of mechanical working environment,” said Steve Phillips, president of Allied Oil & Supply. Thus, lubricant filtration is an essential component of any well-run operation.
Filtration is best for removing solid particulates, but other types of contaminants are harder to remove this way. Oxidation products that can deposit varnish on machine parts and pipes can be removed through flushing or specialized filtration techniques. Depending on the size of the reservoir and the extent and nature of the contaminants, the presence of other lubricants, solvents or cleaners in a reservoir might require disposing of the lubricant and starting fresh.
However, STLE member John Erikson, vice president of fluid services for Dilmar Oil Co., Inc., explained that as much as 82% of mechanical wear can be attributed to solid particulate contaminants in a lubricant. Solid particulates from outside (dust or sand, for example) often initiate mechanical wear, which releases more particles into the oil. “It’s a never-ending cycle,” he added. “The more contaminants you take in or create within the oil, the worse it gets.
Everyone has a maintenance program
“All of our customers, whether they know it or not, are on some type of maintenance program,” said Steven Benton, Allied’s industrial services operations manager. At one end of the spectrum is “running to failure,” which is exactly what it sounds like: a customer runs the system as cheaply as possible, and when something fails, they make repairs as cheaply as possible. The next level up is a preventive maintenance program, where, for example, the customer swaps out a rotor every 10 years, whether the rotor needs replacing or not.
The next level is data-driven predictive maintenance. Routine monitoring and periodic oil analysis reports are used to identify long-term trends, as well as excessive vibrations, particle releases or other warning signs that maintenance or repairs are required. The “holy grail” is the proactive program, Benton said. This approach mixes aspects of prevention and prediction, and it requires adequate amounts of money, staffing and the necessary knowledge base to implement it and keep it up. “Customers are beginning to understand the value of being proactive when it comes to filtration activities,” he said.
At any level of maintenance, Benton said, effective filtration is the central point. Particle counters provide basic-level information on oil cleanliness, as well as an early warning system for wear problems in the making. Laboratory analysis can provide a running record of particle count trends over time, as well as identifying wear metals and viscosity trends. Onsite particle counters mounted in line or on filter carts monitor particulates in real time, and they can relay an alert to a floor supervisor’s mobile phone if a situation requires immediate attention.
Mark Lynn, Allied’s industrial services general manager, adds that the characteristics of a customer’s system helps to determine how clean the oil should be. Because today’s base oils and additive packages make lubricants more durable, they can withstand higher temperatures and pressures, and they often remain in service longer than earlier lubricants. This makes it even more important to keep accumulations of solid particulates and other contaminants at acceptable levels. Acceptable particle counts depend on the types of pumps and valves in a system, which, in turn, determine the system pressures. High-pressure systems (greater than 3,000 psi) require much lower particle counts than systems operating at lower pressures.
Operations of all sizes
Various sizes of operations differ in their needs for filtration, Phillips said. Smaller operations can have their distributor retrieve drums or totes of used oil and transport these back to the distributor’s facility for reclamation. Reclaiming used oil can be as simple as running the oil through a filter cart or as complex as centrifugation, vacuum dehydration and several stages of filtration.
For operations on the scale of thousands of gallons, a service company’s tractor trailer can bring a centrifuge, vacuum dehydrator, filtration panel, tanks, a generator and a testing lab to a customer’s site. Customers needing filtration several days a week throughout the year might have filtration equipment installed permanently onsite, which saves wear and tear associated with transporting the filtration equipment, along with reducing labor costs.
Customers with systems that require a great deal of filtration can invest in the training, equipment and supplies to do as much maintenance in-house as is practical. “For someone to make a $100,000 investment in something like that, they need to be doing quite a bit. Otherwise, their return might be very limited,” Phillips cautions. However, in cases where getting an additional 10 years of life out of a piece of equipment produces savings in the millions of dollars, the investment is well worth it.
Green practices can save green money
Keeping lubricant oil in good condition for a longer time saves both purchase and disposal costs. STLE member Greg Livingstone, chief innovation officer at Fluitec International, explains that his company’s goal is to convert industrial lubricants and develop new oils into for-life oils, so that operators never have to change them. He added this is an aspirational vision, but moving in this direction requires filtration, additive replenishment and monitoring the whole process.
“We’re involved in each step of that ecosystem,” he said. “All of this has to be done in a safe way that only increases reliability,” he continues. “But if you do this responsibly, we’ve shown that you can, at a minimum, double the life of oil, and, in some cases, we’re looking at a four to five times increase in the life of oils.”
Solubility enhancers, which are high-solubility synthetic base oils added to an in-service oil, are another means of extending an oil’s service life. These supplements can prevent degradation products from coming out of solution and prematurely fouling filters, as well as preventing varnish.
Filter manufacturers are increasingly providing filter casings that can be reused or recycled, which cuts down on disposal costs and waste. Paper or fiber inserts can be removed and disposed of, and the end caps, wire meshes and center cores can be used again and again. This cuts the amount of waste by 80%-90%, Livingstone said, no small savings in the $3 billion per year industrial lubricant filtration market.
Larger manufacturing operations also benefit from reclaiming oil that would otherwise go to waste. Leaks are inevitable in these operations, and well-designed systems have drainage sumps that collect this leaked oil. Each type of lubricant is collected separately, dried and filtered, and returned to service in the same application. In some cases, this reclaimed oil can be cleaner than oil received from the distributor, Phillips notes, although lab analysis will indicate whether the additive levels and viscosity are still up to par. Reclaiming leaked oil is not only good for the environment, but the reduction in waste and disposal costs can save about half of a company’s lubricant costs, Phillips said.
New systems, new lubricants, new problems
Livingstone notes that, in order to remain competitive, original equipment manufacturers (OEMs) constantly find ways to reduce the weight of their machinery and increase the operating efficiency. “Everything is being shrunk down to the smallest size possible,” he said, including oil reservoirs, pumps and filters. Meanwhile, operating temperatures and pressures are going up, and engines and compressors are running faster. The result is a smaller quantity of lubricant operating under more extreme conditions
“The hotter you run the oil, the more chances you have for oxidation,” Erikson said. Heat enhances the catalytic activity of small particles, which accelerates the formation of oil degradation products that can form deposits on pipes and tanks (see Cleaning the Pipes). Oxidation also increases an oil’s viscosity, which increases drag. Increased drag generates more heat, which increases oxidation still further.
Cleaning the pipes
Filtration removes particulates that are floating in the oil, but cleaning residue from pipe and tank walls often requires high-velocity flushing, which helps operations to meet the minimum requirements for oil systems covered by API 614. “The oil systems are like their own little neighborhood,” Benton said, adding, “They’ve got their own pumps, their own filters and their own coolers or heat exchangers.”
Over time, these systems are exposed to rapid changes in temperature and pressure, as a result of operating conditions and the outside environment. Oils oxidize and deposit varnish, steel can release wear particles like rust or carbon, and dirt and dust from the outside air can become trapped in deposits on the pipe walls. Certain hot oil systems that heat bulk product tanks can deposit insulating layers of coke that greatly decrease the efficiency of these systems. A high-velocity flush lasting anywhere from a few days to a week or two can remove 10-20 years’ worth of contamination, Benton said (see photos).