Cooling Technology Institute Announces Updated Sound Rating Method

In November, 2019, the Cooling Technology Institute released its latest revision of Acceptance Test Code 128, Measurement of Sound from Water Cooling Towers, which is the Industry’s recognized standard specifically for published sound data provided by manufacturers of package cooling towers used on HVAC, industrial and process cooling systems. The updated technique for sound power calculation of package towers was adopted after extensive research, sound modeling, product testing and comparisons with various internationally recognized sound codes.

In the 2019 edition, the legacy sound pressure measurement locations of 5 feet and 50 feet remain the same and the 15 meter sound pressure measurements are still used to compute the unit sound power. However, the sound emission surfaces have changed along with the associated sound power equation. With this updated method, sound power results are now more indicative of other international test codes. Other code changes for 2019 included modification to the background sound correction and clarification of definitions.

In July 2020, cooling tower manufacturers attending the Virtual CTI Summer Workshop voted unanimously in the ATC-128 Committee meeting that, as of Sept. 1, they have voluntarily began publishing sound power levels in accordance with the latest version of ATC 128. Users of sound data are now urged to check the sound rating method listed on the data sheets provided by manufacturers, which should define which version of ATC-128 has been used to calculate the listed sound power levels. Larry Burdick, chair of the committee, stated, “this agreement will assist those individuals comparing ratings on a given project that the sound values provided by various suppliers are comparable.”

The ATC-128 Committee itself is comprised of representatives from many stakeholder groups, including owners and operators of cooling towers, manufacturers, test agencies, sound consultants and certification organizations.

ATC-128 (November 2019), along with all other CTI standards, codes and guidelines, is available at for a nominal charge. Details of the research, testing and modeling documented in various technical papers, the 2019 Education Seminar and task group records are also available from the CTI.