Semi-hermetic pumps have what type of motor connection?

Semi-hermetic pumps are designed with an external motor that is mechanically connected to the pump through a seal. This design helps to ensure that the refrigerant or fluid being pumped does not come into contact with the motor, which is critical for maintaining efficiency and preventing contamination of the pump oil with refrigerant. The use of a mechanical shaft seal allows for a secure connection between the internal components of the pump and the external motor, enabling reliable operation under varying conditions.

This setup provides several advantages, including improved serviceability, as the external motor can be easily replaced or serviced without having to dismantle the entire pump assembly. Additionally, having an external motor contributes to lowering the temperature of the motor since it is not directly exposed to the operational temperatures of the refrigerant, potentially leading to longer operational life and reduced energy consumption.

In contrast, other designs, such as having an internal motor, may pose challenges regarding maintenance and reliability due to potential exposure of the motor windings to the refrigerants. The characteristics of semi-hermetic pumps make the external motor with a mechanical shaft seal the correct answer, as they specifically align with the design principles and practical applications of such pumps in refrigeration systems.