What Is ASHRAE 52.2?

ASHRAE Standard 52.2, officially titled “Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size,” is a widely recognized standard developed by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). It provides a standardized methodology for evaluating and determining the efficiency of air filters in removing particulate matter of specific sizes in general ventilation settings. ASHRAE 52.2 is critical in helping manufacturers, HVAC professionals, and end-users compare and select appropriate filters, ensuring that they perform adequately in mitigating particular airborne contaminants, thereby safeguarding indoor air quality (IAQ). For industrial dust collector filters, including baghouse and cartridge filters, ASHRAE 52.2 has been supplemented and updated by ASHRAE 199, which is specific to pulse-cleaned dust collection systems. Key aspects of ASHRAE 52.2 include:

  • MERV Ratings: The standard introduces the Minimum Efficiency Reporting Value (MERV) rating system, assigning filters a rating from 1 to 20 based on their capability to remove airborne particles in specific size ranges. (Note: 17 and above are equivalent to HEPA and rarely used.) A higher MERV rating signifies better filtration performance. 
  • Particle Size Ranges: It evaluates filter efficiency across multiple particle size ranges, specifically focusing on particles between 0.3 and 10 microns, to determine how well a filter can remove different types of particulates.
  • Testing Methodology: The standard outlines a specific procedure for testing filters, a means of measuring particle concentration, and a system for analyzing the data to calculate the filter’s performance.


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