CFC - These are the Chloro Fluoro Carbon refrigerants, such as R11, R12, R113, R114, etc. These refrigerants were identified as the most harmful to Ozone layer by the Montreal Protocol, and were phased out in 2000.

There is extensive research going on to identify new refrigerants that can be used to replace the CFC and HCFC refrigerants. Currently R134a is the most commonly used new refrigerant. The various refrigerants have different characteristics, which make them suitable for a particular application.

A periodic refrigerant analysis is important to detect and control contaminants in the refrigerant, which can result in degradation / failure of the various components, and cause inefficient operation of the unit. A log of the periodic refrigerant analysis should be maintained for trending. Refrigerants should be tested for the following contaminants –

Moisture Acid Particulate/solids Organic matter – sludge, wax, tars Non-condensable gases

Moisture is one of the primary causes of contamination-related problems in a refrigeration system. It also results in formation of some of the other contaminants mentioned above, which in turn cause further damage to the chiller or DX unit. Presence of moisture results in following undesirable effects:

Ice formation in evaporator, expansion valve or orifice. Degradation of lubricating oil due to hydrolysis. Acid formation due to hydrolysis of refrigerant in the presence of moisture

and  high temperature. Corrosion of metals. Copper plating

The copper plating phenomenon essentially involves carryover of copper ions from exchanger tubes to the steel surfaces. Although the exact mechanism is not completely understood, it involves the following three steps, 1) oxidation of the copper due to contaminants such as air, moisture & acid, 2) solubilization and transport of copper ions by the lubricant, 3) deposition of the copper on hot clean steel surfaces such as bearings. Excessive copper plating can result in a compressor failure. Typically copper plating is a concern in systems with high level of contaminants and high bearing temperatures.