What are the two primary types of shaft seals used for centrifugal pumps?

The two primary types of shaft seals used for centrifugal pumps are indeed the stuffing box and mechanical types.

The stuffing box is a traditional method of sealing where packing material is compressed around the pump shaft. This method is time-tested and effective, but it can require regular maintenance and can produce leaks if not properly adjusted.

Mechanical seals, on the other hand, are a more modern solution and have become increasingly common in centrifugal pumps due to their ability to provide a more effective seal with less maintenance. They consist of a pair of faces that are pushed together by a spring, significantly reducing the possibility of leaks and improving reliability and efficiency.

In contrast, O-ring and lip seals, while also employed in various applications, are not typically categorized as primary types for centrifugal pump shaft seals in industrial contexts. Radial and angular contact bearings are components related to bearing systems rather than sealing mechanisms. Hermetic and rotary seals, although important, are more specialized types rather than the primary standard options used commonly in centrifugal pumps.