Common Misconceptions About Oil Removal Using Oil Coalescers

Preceding blogs have described oil removal techniques for industrial cleaning in some detail.  It would be nice if this was always a simple consideration – but it is not!

The case for using an oil coalescer is pretty clear cut as long as the cleaning chemistry is truly a “splitter” AND, THE OIL IS NOT WATER SOLUBLE.  If the oil (or lubricant) is water soluble, an oil coalescer will seldom separate and remove it.  A “water soluble” oil is usually comprised of oil, water and a surfactant or emulsifier and other ingredients that allow the two to mix or form an emulsion.  Water also acts as an effective coolant.  This combination can provide a very effective and free-flowing lubricant/coolant while reducing the overall consumption of oil.  However, the same ingredients in the water-soluble lubricant/coolant that allow oil and water to mix also promote the emulsification of oil in the cleaning solution (even if it is, characteristically, a “splitter”).  The result is an emulsion of oil immune to removal using an oil coalescer.  The rare exception to this is a combination of lubricant/coolant and a special cleaning formulation which is able to break the emulsion to allow the separation of oil.  The chemistry is complex and specific products must be used to assure success.

In an extension of the above, if ANY water soluble contaminant is introduced into a cleaning machine, then one might as well consider that all contaminants introduced into that machine are water soluble.  The ingredients from the water soluble components mix with and render the non water soluble components soluble.

As a result of the above, oil coalescers can and should be used under some very specific conditions in order for them to truly perform in the way intended.  But, there are a lot of them used in mis-applications.  Consider the following  – –

I have seen instances in which an emulsifying chemistry was used with an oil coalescer with, ultimately, poor results.  In one particular case I was sent to a facility to diagnose a customer’s cleaning problem.  On arriving, I looked the machine over and didn’t see anything obviously wrong that might result in poor cleaning. I did, however, notice that on the oil coalescer, oil was coming out one pipe and cleaning chemistry out the other yet I KNEW that the chemistry was an emulsifier!  The personnel were quick to put blame for the problem on the washing system saying that it must be the fault of the washer since everything else seemed to be working OK.  To diagnose the problem, I had them re-fill the washer with fresh chemistry.  Amazingly, it performed  superbly!  Parts were as clean as they ever were but, I noticed that no oil was being removed by the oil coalescer.  I continued to visit other customers in the area and, sure enough, three days later got a call from the customer that the washer was again not performing.  So I returned.  Again, oil was coming out of the oil coalescer.  Clearly, the cleaning chemistry had become saturated with oil to the point that it could no longer maintain an emulsion.  The excess oil that could not be emulsified was, in fact, being removed by the oil coalescer but the oil-saturated cleaning solution was ineffective at cleaning.  On further investigation, I found that the customer had changed cleaning chemistry suppliers a few weeks earlier and, not to my surprise, they had changed from a “splitting” chemistry to one that emulsified.  Ultimately they returned to the “splitting” chemistry and the problem was solved.

There is sort of a double lesson in the above.  The first is, If it works, don’t “fix” it.”  The second is, “Things aren’t always as they appear.”  The customer didn’t see a change as a result of the change in chemistry but, in fact, there was a HUGE difference.

–  FJF  –

Leave a Reply