ASHRAE has combined two of its standards to create one new revised standard on filtration. 

Standard 52.2, “Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size,” establishes a test procedure for evaluating the performance of air-cleaning devices as a function of particle size. It has been combined with the former standard 52.1, “Gravimetric and Dust Spot Procedures for Testing Air Cleaning Devices Used in General Ventilation for Removing Particulate Matter.”

“Combining the two standards provides a clean slate to begin significant changes regarding making the method much more technically accurate,” said Robert Burkhead, chairman of the American Society of Heating, Refrigeration and Air-Conditioning Engineers committee dealing with the standard. “Specifically, we have plans in motion to change the MERV (minimum efficiency reporting value) table ranges, narrow the ambient conditions allowed and further refine the instrumentation specifications — all in an effort to reduce the variability of the data product from the standard.” 

Standard 52.2 now incorporates the Standard 52.1 sections on arrestance and dust-holding capacity; and also adds a new appendix. Appendix J provides an optional method of conditioning a filter using fine potassium chloride particles to demonstrate efficiency loss that might occur in field applications.

Burkhead said the new standard addresses three air-cleaner performance characteristics: the ability of the device to remove particles from the airstream, the total dust holding capacity with weight efficiency and its resistance to airflow.

For more information or to order a copy of the standard, visit