What Is Oil Fouling?

Oil Fouling of the heat transfer surfaces of air conditioning and refrigeration systems, will cause a loss of efficiency that will continue to accumulate.

ASHRAE (American Society of Heating, Refrigeration and Air-Conditioning Engineers) confirms that over time performance is degraded by 30% due to the build-up of lubricants on internal surfaces. Higher percentages up to 40% have been observed in systems 20 years old or older.*

In all air conditioning and refrigeration systems, 0.5% to 8% of the compressor’s lubricating oil circulates with the refrigerant.  This oil attaches to the inner walls of the refrigeration tubing and acts as an effective insulator to heat exchange.  It is these oil deposits that ultimately block heat transfer and reduce your system efficiency.

Equipment suppliers may state that in a particular system, migrating oil concentration has been reduced to only 1%. This 1% being referred to is 1% of the total oil volume. If a compressor holds four quarts, or 128 ounces of oil, then at 1%, 1.28 ounces is flowing through the system at any given time. Since a capillary tube, the oil pressure switch or expansion valve can be fouled with a few milligrams of oil, and when 1% of any oil charge is flowing constantly through the system, the system will become oil-fouled.