Pumps are manufactured in standard sizes by manufacturers. The actual requirement for an individual application may be different from the standard size.Thus, the pump can be further optimized to match the requirements. This will improve pump efficiency and can save power. One ways of doing this is by trimming the impeller.
Impeller trimming refers to the reduction in diameter of the impeller to suit the required head. The impeller vanes and the shrouds are both machined to reduce the diameter.