What terms are used to describe the designation and selection of impellers?

The designation and selection of impellers are commonly described using terms such as open, semi-closed, and enclosed. Each of these terms refers to the design of the impeller and its application in pumping systems.

Open impellers consist of a set of blades without any covering, allowing for the free passage of fluid. This design is well-suited for pumping fluids that contain a significant amount of solids or slurries, as it minimizes the risk of clogging.

Semi-closed impellers, on the other hand, have blades that are positioned between two plates. This design offers a balance between efficiency and solids handling, making it versatile for various applications where there may be both clean and slightly contaminated fluids.

Enclosed impellers have blades completely surrounded by a casing, which makes them highly efficient for clean fluids. This design is ideal for applications where high hydraulic efficiency is required and is often used in applications with low solids content.

The other answer choices refer to alternate characteristics or categories that do not specifically align with the standard terminology used in the context of impeller design and selection. Understanding these classifications helps ensure that the appropriate impeller type is chosen based on the specific requirements of the fluid handling system.