Refrigerants Explained
Refrigerant Names and Classification
CFC - Chloro Fluoro Carbon
A compound containing Chlorine, with a high risk of
destroying the ozone layer.
CFC-11, 12, 113, 114, 115 etc.
HCFC - Hydro Chloro Fluoro Carbon
A compound containing chlorine but since hydrogen is
present, the risk of destroying the ozone layer is low.
HCFC-22, 141b, 142b, 123, 225 etc.
HFC - Hydro Fluoro Carbon
A compound which does not contain chlorine and does
not destroy the ozone layer.
HFC-32, 134a, 59, 407c, 410a, 125, 152a
Refrigerant Blends - Servicing Considerations
Unlike pure fluids and Azeotropes, refrigerant blends boil and condense at varying temperatures for a given pressure. The range over which the temperature varies is referred to as temperature glide. Typically R-59 has a glide of 5oC & R-407c has a glide of between 5-7oC, depending upon pressure.
When dealing with blends, pressure temperature tables are presented in an unconventional manner. Two pressures are listed for each temperature: the Dew Pressure and the Bubble Pressure.
The Dew Pressure is used for determining the system pressure when the refrigerant is in a saturated vapour or superheat condition (i.e. on the suction and discharge sides of the compressor).
The Bubble Pressure is used for determining the system pressure when the refrigerant is in a saturated liquid or subcooled condition (i.e. at the inlet to the expansion valve or capillary tube).
Blended refrigerants must therefore only be charged into a system in the liquid state, otherwise partial separation of the blend will occur.
One exception to the above statement is that if a complete cylinder of refrigerant is going to be charged into a given system then vapour charging is allowed, as all the constituent parts of the blend will be charged into that system. To ensure that any cylinder of refrigerant in a service engineers stock retains the blends original composition then vapour charging should be avoided.
If a significant leak develops in a system containing a refrigerant blend and a noticeable drop in performance is recorded then the system charge will have to be mechanically recovered, the source of the leak identified and repaired and finally the system will then have to be fully recharged with new refrigerant.
The overall impact of blended refrigerants will therefore increase the cost of servicing equipment in the field and increase the initial capital cost of new equipment because of the higher cost of the refrigerant itself.