The paper describes and discusses methods for testing and rating cabinet fans, in particular, methods for testing and rating central station air-handling units as outlined in ARI Standard 430-78, Central Station Air-Handling Units. It also reviews and emphasizes general laboratory test techniques for aerodynamic testing of air-moving devices. By becoming more familiar with cabinet fan testing and rating methods, specifiers and users can properly select these fans, resulting in successfully applied equipment and trouble-free system operations. Fans are tested, rated, and cataloged under ideal conditions, but ideal laboratory conditions are rarely available on the majority of installations because of space limitations. A number of specifics are pointed out where significant differences in fan performance can occur.