Types of compressor casing
Most compressors are driven by electric motor:
Or sealed/semi-hermetic:
- Built in the same housing as the compression parts. Hermetic compressors built in welded shell, and no access to the internal parts for maintenance or repair. - Semi-hermetic compressors collected with removable covers, usually seal gaskets, which allows a limited amount of access to on-site service. Hermetic compressors and more semi-hermetic (higher-about 8 kW of engine power) compressors are usually suction gas cooled, i.e. the refrigerant is cooled engine before compression. This reduces the performance of the compressor. Externally cooled types of compressors where the steam passes directly into the cylinders, usually around 8% more efficient than the equivalent of suction models.
Or open type:
- With drive shaft passing through rotating vapor barrier (open type).
The motor is connected to the external shaft or with direct coupling or belts. The motor should be accurately size for compressor duties and starting torque requirement. Start the engine below its design debt reduces its power factor and efficiency. When comparing the power consumption of the open and semi-hermetic compressor drive motor efficiency losses and need to be considered open to drive cars. High-efficiency motors, generally available and now the price is about the same as standard motors.
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Compressors