New Oil Is Not Clean Oil
EP Editorial Staff | May 1, 2023
Proper storage and handling are critical success factors for precision lubrication.
By Mark Barnes, PhD, CMRP, Des-Case Corp.
After 27 years in the lubrication industry, I continue to be amazed at how few people in the maintenance community understand that new oil is not clean oil. Don’t believe me? Take a look at the two new oil samples shown in Figure 1—one from a 350-gal. tote of mineral-based EP 220 gear oil, the second from a 55-gal. drum of EP 320. Both samples were taken from freshly delivered oil from a major, name-brand supplier.
Looking at the raw particle counts, it’s clear that the tote of EP 220 has been filtered prior to delivery, but only to around 25 microns, as witnessed by the sudden drop in particles between the 21- and 38-micron particle size ranges. By contract, the barrel of EP 320 has a relatively low concentration of particles >14 microns but is still very dirty below the 14-micron size range, indicating that this oil has been filtered to around 12 microns. Neither of these new oils is fit for purpose without additional filtration if the goal is to achieve an optimum fluid cleanliness of ISO 18/16/13 or cleaner, which is recommended for critical gearbox applications.
Why is an oil supplier delivering dirty oil? The reality is that the pathway from manufacturing a finished lubricant to the point at which the consumer receives the final product involves several “touchpoints,” each of which presents an opportunity to introduce contamination.
By way of illustration, consider how something as basic as a conventional mineral-based AW 46 hydraulic fluid arrives at an end-user site. Like any other finished lubricant, hydraulic fluid is made by blending a base stock from one supplier with an additive package from another source. After blending, the finished product is distributed to the market in bulk (either rail car or tanker truck) to national and regional distribution before arriving at a local oil-distribution center.
Once at the local supplier, an end user might order four barrels of AW46 fluid. The distributor will typically fill four empty barrels, which may be either new or reconditioned, for delivery to their customer. Considering this convoluted manufacturing and delivery pathway, the complexity and, most important, the incremental costs to filter new oil down to the 3- to 6-micron range and guarantee that this level of cleanliness is retained through the delivery process is more than most end users are willing to pay, for what is still largely viewed as a commodity item to be purchased at the lowest price-per-gallon.
How can you ensure that the oil you put in your critical assets is clean and dry? The first rule is to buy lubricants in the smallest quantity feasible for the application. Figure 1 illustrates a common trait with new oils: the smaller the container, typically the cleaner the oil. While it isn’t realistic to fill a 200-gal. reservoir from quart containers, oil shipped in four barrels is probably going to be cleaner than that from a bulk or tote supply.
Set cleanliness targets for the supplier that are realistic and achievable. For example, if your ultimate cleanliness target for gear oil is 18/16/13 and less than 200 ppm of water, set a requirement that the supplier deliver oil that is within two ISO codes (20/18/15 or cleaner) and meets the minimum water targets. The reason for the tighter targets for moisture is because water will destroy additives in storage and create internal contaminants from rust and corrosion of steel vessels.
It’s also a good idea to set QA targets and ensure effective QC processes are established for new lubricants. For large-quantity supplies, such as bulk or tote delivery, sampling each new batch of oil received is considered a best practice. The goal is not only to ensure minimum cleanliness and dryness targets are met, but to make sure that critical oil properties, such as viscosity and additive content, are correct. Wherever possible, new bulk oils shouldn’t be used before a QA check provides a clean bill of health. For barrels and smaller quantities, test random samples upon delivery and, at a minimum, yearly.
Accepting that the new oil we receive may not always be clean, best practice calls for each new oil to be pre-filtered a minimum of five to seven times prior to use. This includes particulate filtration and water removal, where required. If possible, do not filter gear oils and engine oils below seven microns to avoid stripping additives.
All oil-storage vessels, whether they are a 10,000-gal. bulk tank or a 55-gal. drum, should be equipped with a desiccant breather to ensure that air that enters the vessels as oil is dispensed is clean and dry. This critical step is often overlooked.
For example, consider hydraulic fluid in a barrel with a desired target cleanliness of 16/14/11. This level of cleanliness means fewer than 160 particles of 6 microns and greater in each milliliter of fluid. Six microns is about the same size as a human red blood cell. Now imagine dispensing half of the fluid from a 55-gal. drum and replacing it with typical plant air. How many red-blood-cell-sized particles will be in 25 to 30 gal. of plant air?
To avoid contamination during oil transfers, all transfer points should use quick connects or hard piping. This includes from the barrel to any top-off containers or from the barrel or top-off containers to the machine.
Fluid cleanliness is a holistic process. It requires that every step of a fluid’s journey through the plant be carefully controlled and it all starts with new-oil cleanliness. Lubrication storage also speaks to an organization’s “lubrication culture.” A messy, dark, dirty lube room indicates that lubrication is a low-priority activity that has little intrinsic value to the company. By contrast, a lube room that is well lit, orderly, and ergonomic indicates that lubrication is a foundational pillar of a reliability-driven asset-management strategy. EP
Mark Barnes, PhD, CMRP, is Senior Vice President, Global Business Development, at Des-Case Corp., Goodlettsville, TN (descase.com). He has more than 25 years of experience in lubrication management, and oil analysis.