1.1 This specification covers the acceptable details and tolerances for the plenum chamber used in specified air performance measurement tests for vacuum cleaners.

1.2 The plenum chamber is designed for vacuum measurements only. (Warning - The plenum chamber has been shown to accurately determine maximum air power values at various test points for vacuum cleaners. There is a possibility that the airflow values measured with orifices larger than 2 in. at high flow rates may be erroneous due to the proximity of the top and bottom surfaces to the orifice plate inlet.)

1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.