Hermetic sealed compressor
Hermetic sealed compressor: A hermetic sealed compressor is one in which both compressor and motor are confined in a single outer welded steel shell. The motor and compressor are directly coupled on the same shaft, with the motor inside the refrigeration circuit. Thus the need for a shaft seal with the consequent refrigerant leakage problem was eliminated. All the refrigerant pipeline connections to the outer steel shell are by welding or brazing. The electrical conductors to the motor are taken out of the steel shell by sealed terminals made of fused glass. Hermetic compressors are ideal for small refrigeration systems, where continuous maintenance (replenishing refrigerant and oil charge etc) cannot be ensured. Hence they are widely used in domestic refrigerators, room air conditioners etc. Since, the motor is in the refrigerant circuit, the efficiency of hermetic compressor based systems is lower as the heat dissipated by the motor and compressor becomes a part of the system load. Also material compatibility between the electrical winding, refrigerant and oil must be ensured. Since the complete system is kept in a welded steel shell, the hermetic compressors are not meant for servicing. A variation of hermetic compressor is a semi-hermetic compressor, in which the bolted construction offers limited serviceability.
Advantages : 1) The hermetically sealed compressors can be moved easily from one place to the other place, they are highly portable. More compact unit and required less space. 2) It is less noisy than ordinary system. 3) No coupling, belt or pulley is involved, the maintenance is lesser. 4) The lubrication system of the hermetically sealed compressor is inherent and no external lubrication is required, unless the fresh gas charging is done. 5) The installation of the hermetically sealed compressor is very easy. 6) Hermetically sealed compressors have very long life. 7) The leakage of refrigerant is completely avoided.