In what type of compressor is a mechanical shaft seal necessary?

A mechanical shaft seal is necessary primarily in open type compressors. Open type compressors are designed with a motor that is separate from the compressor housing, which means that the shaft connecting the motor to the compressor has to penetrate the compressor housing. To prevent refrigerant leakage from this shaft penetration, a mechanical seal is used. This seal ensures that the refrigerant does not escape, maintaining system pressure and efficiency.

In contrast, other types of compressors, such as rotary, scroll, and reciprocating compressors, either have the motor built into the compressor housing or use other sealing methods that do not require a mechanical shaft seal. Therefore, the design configuration of open type compressors makes a mechanical shaft seal essential for their operation.