Although you should dynamically balance an impeller to ISO 1940 standards (level depends on speed, size, sensitivity, etc), you might buy a static balancer for cheap and manually grind off the heavy spot. It isn't very accurate, but that is the crude way.
One aspect that is usually overlooked when discussing balance is the importance of the impeller's hydraulic balance, that is an impeller with: correct blade spacings; equal blade thickness; and equal area / volume of the waterways.
An impeller in terms of mass distribution can be "dynamically balanced" even though it has unequal blade spacing, unequal blade thickness or unequal waterway passages. A hydraulically unbalanced impeller in operation can exhibit problems due to uneven loading of the rotating element that appear as a unexplained out of balance phenomenon -- it can be difficult to pin-point the vibration / out of balance source if hydraulic balance is not considered when trouble shooting the problem.
International College
Naresuan University
Phitsanulok
Thailand
About what kind of impeller we do speak ?
It is an impeller of a multi stage pump or a single impeller for a single stage pump. If the application, the diameter, the weight and the speed would be available, an anwser can follow.
To balance an multi stage impeller dynamic makes no sense because later, after the assambly of the pump rotor you have to balance the hole rotor dymamic on the firts and last impeller you reduce the unbalance and on the middle impellers the natural fequency. If you have maybe an impeller for a main cooling water pump you have to balance it direct dynamic.
With the help of exact datas it would be possible to help you better.
Balancing the rotating parts of a pump is dependant on the type of pump. For example:
Many ANSI (Typical Chemical Processing Pumps)are single plane balanced (also known as static balance). This can be done by placing the impeller on a shaft and mounting this between two free rotating wheels.
API (Refinery Pumps) are generally two plane balanced. The impeller installed on a shaft is spun at high rpm, and imbalance is monitored in two planes. The imbalance tolerance should be specified based on ISO 1940 Standards.
Multi-Stage Process Pumps are balanced in many different ways. Some will have each impeller independantly balanced, then all impellers assembled with the job shaft and coupling half (with key) and then balanced as a complete assembly.
Tolerances depend on the reliability requirement of the pump, the pump speed (rpm), and the general design of the pump. Manufacturers should be consulted on their standard balancing procedures.
