15-25: Leveling the Playing Field for Axial Impeller Comparisons and Regulatory

Axial Impellers are integrated as driven impellers in multiple non-fan products, including cooling towers. However, there is no common rating standard for axial impellers. That means that a level playing field for axial impeller performance comparisons is absent. No commonly accepted standard for comparing axial impeller data on an apple-to-apple basis exists. There is no commonly accepted guide for compliance officers to follow to support the implementation of regulatory minimum efficiency requirements. Perhaps therefore, some traditional fan manufacturers lobby for having axial impellers integrated into cooling towers tested as complete assembled fans. That means with the specific fan housing geometry section of the cooling tower! In those cases where the cooling tower section and impeller is too big for testing it’s suggested to test a scaled down replica or do in situ testing. To avoid that “not very meaningful” situation and to help create an even playing field, an initiative is pursued to ensure the development of a standard set of fan parameters to be set for testing of axial impellers. This may then be accepted by regulators in lieu of fan performance compliance verification, when the testing of the fan is impractical, represents an undue burden to the customer and may be technically unjustifiable.