Air mixers are frequently used in air-handling equipment to reduce the amount of stratification within the air-handling unit. At this time, there are no performance standards for these devices so there is no way to objectively rate their performance. This paper presents a test method that can be used to rate the mixing performance of these devices under conditions typically encountered in actual air-handling systems. This test method is based on a test apparatus developed in 1966 by the National Institute of Standards and Technology (NIST), then known as the National Bureau of Standards, for studying the performance of air mixing devices. A method is presented to calculate the range mixing effectiveness with confidence levels of 95% and 99% based on the numbers of temperature measurements used. The ratings developed from this test method will allow system designers to objectively analyze the performance of the various air mixers that are commercially available.

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