How do ion exchange resin filters target unwanted molecules? Ion exchange resin filters can be tuned based on the polarity of the base oil and additive chemistry of the fluid being treated. Testing prior to use on site can ensure that the additive package will be preserved.
Rafe Britton: The objective with filtration technologies is “remove the bad stuff keep the good stuff in”. When most people conceptualize filtration technologies, they envision particulate filters that can only discriminate on particle size. This is a blunt instrument. With resin media we utilise charge and polarity select the species of contaminants for removal.
This works because most oxidation products are polar. But many additives are also polar. How are we able to selectively remove the oxidation byproducts and without stripping an additive package?
Peter Dufresne: When we started, we started with the fire resistant synthetic lubricants (FRFs) and they contain no additives. This is like a doctor selecting antibiotics. They could use a broad spectrum antibiotic and be as aggressive as possible with the chemistry because there are no additives to remove. The fluid is pure additive.
As we moved into additized products, starting with R&O lubricants used in rotating equipment; those are about 98 to 99% pure base oil and 1 to 2% additive.9 0% of that is comprised of antioxidants.
These polar additives are very limited and often short-lived so we de-tune the range of the contamination removed. This way we do not remove the additive and the oil. This is one reason we test every site before we apply ion exchange resins, just to confirm to a hundred percent degree of certainty that additives will not be removed. It is almost an unnecessary exercise. We [have a library of oils from different companies] and done them a hundred times and the resins don’t remove additives.
With more additized products like AW oils, it’s becoming more and more of what the science is about when engineering ion exchange resins. We cannot just take resins off the shelf and put them in a filter and expect them to work because the variability present is huge. We are tuning the reservoir, just like antibiotics are tuned. You want a very broad spectrum or you want a very narrow spectrum.