Machine Coolant and Tramp Oil

Tramp Oils are a huge problem.  Skimmers work but only on about half of tramp oils.  We took a sample of coolant and let it settle out.  Eventually the tramp oils and grease settled out in layers on top of the coolant.  However it took a day for half the tramp oil to float to the top and weeks for all of it to finish floating to the top.  

Close up showing two separate layers of tramp oil

Tramp Oil Separation Over Time

This is the number of ml. of tramp oil that separated out of 250 ml of coolant.  About 90% of the tramp oil floated to the top in the first 33 minutes.   There was no change at 73 minutes.  At the end of the first day another ml had floated out and maybe anther milliliter by the end of the second day.  If the purpose is to recycle the coolant then a half hour of settling might be optimal.