(Supersedes ANSI/ASHRAE Standard 133-2001)

Standard 133 provides procedures for testing direct evaporative cooling devices under laboratory conditions to obtain rating information. As an ASHRAE method-of-testing standard, it is intended to offer recommended practices and accurate measurement procedures. In addition, the committee incorporates the effects of ambient conditions, testing error, instrument accuracy, and the need to make certain that no other sources of heat transfer are taking place during the testing.

This standard establishes a uniform method of laboratory testing for rating packaged and component direct evaporative air coolers. The scope of this standard covers a method of testing for rating the saturation effectiveness, airflow rate, and total power of packaged and component direct evaporative air coolers. Covered tests also include the methods for measuring the static pressure differential of the direct evaporative air cooler, density of the air, and speed of rotation of the fan. This standard requires that packaged and component direct evaporative air coolers be simultaneously tested for airflow, total power, and saturation effectiveness. The ratings resulting from application of this standard are intended for use by manufacturers, specifiers, installers, and users of evaporative air cooling apparatus for residential, commercial, agricultural, and industrial ventilation; for air cooling applications; and for commercial, industrial, and agricultural processing applications.

This 2008 revision makes two key changes to Standard 133-2001. First, the difference between the dry-bulb and wet-bulb temperatures has been decreased from 25°F to 20°F (14°C to 11°C). The committee agreed that this would increase the times when testing could be accomplished using unconditioned air and still not reduce the accuracy of the test. Second, to provide better flexibility, temperature measurement in Section 6.1.1 is no longer limited to specific types of instruments as long as they meet the requirements of ANSI/ASHRAE Standard 41.1, Standard Method for Temperature Measurement. Various other improvements were made as well: all references were updated to the latest editions and mandatory language was clarified by changing "will" to "shall."

Keywords: direct evaporative coolers, testing evaporative coolers, testing evaporative air coolers, direct evaporative air coolers

Units: Dual