Hermetic Compressors

When the compressor and motor operate on the same shaft and are enclosed in a common casing, they are known as hermetic sealed compressors. These types of compressors eliminate the use of crankshaft seal which is necessary in ordinary compressors in order to prevent leakage of refrigerant. These compressors may operate on either reciprocating or rotary principle and may be mounted with the shaft in either the vertical or horizontal position. The hermetic units are widely used for small capacity refrigerating systems such as in domestic refrigerators, home freezers and window air conditioners. The hermetic sealed compressors have the following advantages and disadvantages

Advantages

1. The leakage of refrigerant is completely prevented. 
2. It is less noisy. 
3. It requires small space because of compactness. 
4. The lubrication is simple as the motor and compressor operate in a sealed space with the lubricating oil. 

Disadvantages 

1. The maintenance is not easy because the moving parts are inaccessible. 

2. A separate pump is required for evacuation and charging of refrigerant. Crankshaft 

Internal working of a welded hermetic compressor.