Are you confident your cooling tower fan performance measurements are accurate? The most reliable tests are conducted in a lab test cell under controlled conditions using precision instruments. Field-conducted air flow tests can be impacted by several factors, including the number and locations of air velocity readings, inlet/outlet obstructions unique to the installation, and static pressure variations due to test instrument location.
Lab test facilities using data acquisition systems to monitor instruments throughout the air flow path provide accurate, stable, unbiased, and repeatable data. ANSI/AMCA Standard 210-16/ASHRAE Standard 51-16 establishes uniform lab test methods for fans and is the cornerstone of the AMCA Certified Ratings Program.
If field tests are required, thermal performance is a better indicator of cooling tower fan performance than air flow. Thermal performance tests measure heat balance and determine if all cooling tower components are performing as designed. Methods used for thermal performance testing are less prone to the bias when measuring air flow static pressure and air velocity in the field.
Remember, performance of fans used in cooling towers is not regulated. Published fan data should be scrutinized to confirm that testing used to support the data is reliable and repeatable.