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Several factors indicate that additive removal by filters is nonexistent in properly maintained lubricant systems.
LUBRICANT MANUFACTURERS FACE EXTENSIVE CHALLENGES in formulating products for their end-user customers. Several articles have been published in TLT discussing many techniques for helping lubricant companies and end-users achieve superior performance for their lubricants and production machines.
One issue that has not received much attention is concern about whether filters are involved in removing additives from lubricants. There is no question that the role of filtration equipment in maintaining lubricant systems is crucial. In the November TLT, an article based on a Webinar presentation sponsored by STLE University reviewed the fundamentals of filtration.1 (available digitally at www.stle.org.)
Filters serve the purpose of removing contaminants from lubricant systems that, if left, can significantly reduce operating life and affect the performance of production machines. The particles trapped from filters can range in size from 40 microns down to the 6-10 micron range. This latter range is the focus for most filters.
Concern has been raised in the lubricant industry on an anecdotal basis that filters might also remove additives from lubricants as they remove contaminants. Such a scenario could reduce the effectiveness of the lubricant and adversely impact its application. The purpose of this article is to gain insight from key industry experts representing the additive supplier, basestock supplier, lubricant supplier and filter-supplier market segments on this issue.
None of the six respondents interviewed wished to be identified, so they will be referred to as:
1. Additive Supplier
2. Basestock Supplier
3. Filter Supplier No. 1
4. Filter Supplier No. 2
5. Filter Supplier No. 3
6. Lubricant Supplier.
ADDITIVE VULNERABILITY
The initial topic that needs to be covered is the solubility of additives in the main types of basestocks that are used in the lubricant industry. This covers the four types of mineral oils (Group I, II and III) and naphthenic oil, polyalphaolefins (PAOs-Group IV) and the synthetic basestocks grouped into Group V (dibasic and polyol esters, polyalkylene glycols (PAGs), phosphate esters and alkylated aromatics).
The additive supplier representative says, "Virtually all types of additives follow the same trend as we move from Group I to Group IV-the solvency of the oil decreases such that some additives that appear to...