Your lube oil tank might need a breather… but not the kind of breather you need after a long day at work!
Refineries are not ‘clean’ so don’t expect new oil to be.
Next time that you see a tote of brand new oil arrive from the supplier, crack the lid and have a look in the top hatch. If the oil is clear you may see at the bottom the by-product of the manufacturing process – a layer of dirt. If you cannot see into the tote when its full, then find a recently emptied tote and see what’s in there. That dirt will damage close tolerance machinery and must be removed before service. In addition to the layer of dirt you can see, the oil will hold more in suspension, so don’t be fooled that the dirt isn’t making it into your machinery.
Sedimentary contamination in new ISO32 oil.
Oil Refineries are not the cleanest environments and particulate contaminant and some moisture are an expected by-product of the manufacture of your oil. The onus is on you to ensure that new oil is filtered ready for service when introducing it into the existing lube tank. Typically new oil will contain plenty of unwanted dirt, fibres, silica, and some attractive looking crystals!This photo was taken specifically for this article from a single 100ml sample we took from a tote of oil. What you can see is a wide array of unwanted particles and fibres.
Is Oil Cleanliness Really that Important?
At a microscopic level the cleanliness of lubricating oil is critical for close tolerance machines and hydraulic systems as film thickness can be only a few microns thick. Bearing surfaces rely of boundary layer lubrication and any introduced particles will create wear and then wear debris further compounds the problem.
Introduced contaminants risk lodging in the gaps between bearing surface asperities. Any contact with the asperities creates wear debris.
Visual result of wear from a patch test of 100ml sample of turbine oil showing wear debris viewed at 100X
What should you do?
The process of getting oil to your site is lengthy and can involve a number of differing vessels the oil must pass through before you use it. A properly specified filter cart at the final point before introduction to your machinery is the best place to filter or polish the oil. By completing a single pass of filtration on the oil as you pump it into your machine you will make a significant improvement. Once in service, a kidney loop filtration setup of the lube tank will take care of the old and new oil and work to maintain cleanliness long term.
Will filtering the oil remove desired Additives?
Using a single or multi-pass filtration process on new oil before it is committed to service will improve the cleanliness and will do no harm. If you are using an oil with heavy additive packs such as molybdenum then be wary of filtration by centrifuge as this may strip Extreme Pressure or Extreme Wear protective additives.
Are the OEMs aware of the Problem?
Manufacturers like Cat produce cleanliness requirements for their equipment. The table below is taken from the Cat Commercial Diesel Engine Fluids Recommendations and indicates their target ISO cleanliness codes. Your oil must exceed your OEM expectations to achieve target equipment life.
Every step you take to improve the cleanliness of oil before it enters the lubrication circuitry of your machinery is a good one. With perfectly clean oil, machines can run virtually forever. See our article here.
No System has ever failed from being too clean!