This is no laughing matter. Most plant maintenance workers are oblivious to the amount of contamination that invade drums and totes that sit idle in storage. Even worse is the general ignorance of the damage caused by these intruders after they arrive. An attitude of “out of sight out of mind” leaves these lubricants vulnerable initially, and later the machine, when the impaired lubricants are put in service. By protecting oil drums against contaminantion during storage, you can ensure lubricants are clean, cool, and dry when they enter machinery.
False Perception of Sealed Containers
Drums and totes exposed to day-night temperature swings tend to have the greatest potential for particle and moisture ingression. As temperature changes, air is inhaled and exhaled through due to temperature-induced pressure changes in the head space of the vessel. This can easily occur even though the ports appear to be sealed tight. Experience has taught us that a threaded bung or vent cap on an oil drum is no assurance of a tight fit and seal. The larger the head space and the wider the temperature swing the more pronounced the problem.
Incoming air brings with it moisture and often small particles. As the vessel continues to cool, condensation sweats the headspace ceiling and walls. Water drips into the oil where it is absorbed and free water falls to the vessel flow and puddles. Each evening or cooling cycle the precipitation/condensation occurs again.
More and more water and particles travel downward and build up in the bottom zone of the drum or tote. It is not uncommon for inches of sludge water to accumulate. The best way to prevent this and ensure a sealed container is through the use of a protective device that increases the headspace air pressure, which acts as a barrier against contaminants.
So What’s the Big Deal?
Cold oil can also cause additive precipitation. The colder the oil the bigger the issue. The additives stratify to the lower zone of the vessel where the water and dirt reside.
What occurs next seems to be relatively unknown or at least unspoken by people who are in charge of lubricant and machine health. Once the precipitating additives make contact with the low-lying water, they combine to form a pasty, sludgy mass. The chemistry of the additives changes by hydrolysis and oxidation.
In other words, the additives are dead. Nor can they be resuscitated by agitation or heating. The condition is irreversible.
Eventually the time will come when the maintenance staff begins dispensing oil from the vessel into transfer containers or directly into the machine’s sump or reservoir. If the vessel is a drum, a pump pick-up tube is inserted through the bung hole and pushed down to the bottom. This is where the gooey, sludge mass of water, dirt and dead additives reside.
This destructive material will be sucked up by the pump and discharged into the machine. Oxidized oil and additives propagate like the Covid virus. As the sludge spreads, this stresses the healthy oil in the machine and before long the entire charge of oil becomes oxidized and turning black. The oil filter will plug and internal oil-wet surfaces will become coated with deposits and varnish.
It is a chain reaction of events that leads ultimately to machine failure.
Other Concerns
Drums stored outside can get covered with dirt and water. Cold temperatures can draw these contaminants as solids and liquids straight through unsealed openings into the internal space and the oil (or grease). Polar additives like rust inhibitors, fatty acids, anti-wear additives, dispersants and detergents can rapidly become adherent to the surface of these suspended particles. That ties up the additives making them unable to perform its intended function.
There are so many other issues associated with allowing contaminants to invade lubricants in storage. To a large extent the harm done by the contaminant to the lubricant and the machine is far greater than if the same additives were added directly into the circulating oil in the machine.
How to Stop this From Happening
Don’t just assume your drums and totes are unaffected. Take the following steps to help ensure they stay clear from moisture ingression:
- Do everything possible to keep your stored lubricants sealed from cyclic ambient air movement.
- Avoid storing your lubricants in areas where temperatures change.
- Avoid storing your outdoors exposed to dust, precipitation and day-night temperature changes.
- If needed use a drum cover to keep the top of your drums clean.
- Use a headspace alarm device to quickly alert you to breached seals and other unsealed vessel openings.
- If bottom sediment and water are suspected, sample the bottom of the vessel for inspection before pumping the oil into the machine.
- Always discharge new oil through filters before entering machine.
About the Author
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Jim Fitch, a founder and CEO of Noria Corporation, has a wealth of experience in lubrication, oil analysis, and machinery failure investigations. He has advise...
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