Oil in Refrigerant Circuits
The primary purpose of the oil is for compressor lubrication; also sealing and cooling for oil-injected types. The oil specified by the compressor manufacturer should be used whenever possible. Various mineral and synthetic types of lubricant are available and Figure 5.1 gives some indication as to their suitability with refrigerant type. A blank indicates that the oil type is generally unsuited. It is necessary to emphasize that the oil types shown each represent a family of products, which can be blended to give the required viscosity, and it is necessary to use an appropriate grade or product within the family. For example, polyolester (POE) oils are shown as suitable for hydrocarbons, but a higher viscosity grade will generally be required for hydrocarbons when compared
|
Refrigerant type |
Traditional mineral oil (MO) |
Alkyl Benzine (AB) |
MO + AB |
PolyPolyolester Polyalphaolefin alkalene- (POE) glycol (PAG) |
||
|
CFCs and HCFCs |
S |
✓ |
Y |
K) |
K) |
|
|
HCFC blends |
K) |
✓ |
S |
K) |
||
|
HFCs and HFC blends |
K) |
✓ |
K) |
|||
|
Hydrocarbons |
✓ |
K) |
K) |
✓ |
✓ |
K) |
|
Ammonia |
K) |
K) |
K) |
|||
|
CO2 |
K) |
K) |
|
✓ Good suitability ( ) Applicable with limitations |
66 Figure 5.1 Lubricant types
With that used for HFCs. Moreover, specific additive packages to enhance lubricity or to act as inhibitors may be present in branded products, and this is why the compressor manufacturer should be consulted with regards to changing the specified oil for a particular compressor.
Posted in Refrigeration and Air Conditioning