Which of the following seals would not be used on a refrigeration compressor?

Mechanical seals are typically designed for applications where high pressures and temperatures are present, such as in pumps, but they are not commonly used in refrigeration compressors. Refrigeration compressors usually rely on seals that can accommodate movement and provide a reliable barrier against gas leakage without the complexity of a mechanical seal.

Dynamic seals, soft packing seals, and O-ring seals are all more suited for use in refrigeration compressors. Dynamic seals are designed to allow relative motion between the sealing surfaces and are essential in rotating equipment like compressors. Soft packing seals provide a flexible seal that can conform to irregularities, making them adaptable for various applications within compressors. O-rings offer reliability and ease of installation in low-pressure systems, making them a popular choice for sealing refrigerant in compressors.

In summary, the design and operating conditions of refrigeration compressors make other types of seals more appropriate than mechanical seals, which is why this option is the right answer.