What Are MERV Ratings and How Do They Work?
What is the Minimum Efficiency Reporting Value?
MERV Rating Chart
ASHRAE Standard 52.2 ASHRAE Standard 52.1 Application Guidelines
MERV Rating
Particle Size Removal Efficiency Dust-Spot Efficiency Percent Particle Size and Typical Contaminant Typical Applications Typical Air Filter Type 0.3 to 1 0.3 to 1 0.3 to 1 ≥ 99.999 in 0.1 – 0.2 μm particle size
< 0.3 μm Virus (un attached) Carbon Dust Sea Salt All combustion smoke
Electronics manufacturing Pharmaceutical manufacturing Carcinogenic materials HEPA/ULPA Filters ≥ 99.999 in 0.3 μm particle size ≥ 99.99 in 0.3 μm particle size ≥ 99.97 in 0.3 μm particle size 0.3-1 μm All bacteria Droplet nuclei (sneeze) Cooking oil Most smoke Insecticide dust Most face powder Most paint pigments Superior commercial buildings Hospital inpatient care General surgery Bag Filters – Non supported (flexible) microfine fiberglass or synthetic media, 12 to 36 inches deep. Box filters – Rigid style cartridge, 6 to 12 inches deep. 85-95 75-85 90-95 80-90 70-75 1-3 μm Legionella Humidifier dust Lead dust Milled Flour Auto emission particles Nebulizer drops Superior residential Better commercial buildings Hospital laboratories Pleated filters – Extended surface with cotton or polyester media or both, 1 to 6 inches thick. Box Filters – Rigid style cartridge, 6 to 12 inches deep. 65-80 60-65 50-65 50-55 40-45 30-35 3-10 μm Mold Spores Dust mite body parts and droppings Cat and dog dander Hair spray Fabric protector Dusting aids Pudding mix Better residential Commercial buildings Industrial workspaces Pleated filters – Extended surface with cotton or polyester media or both, 1 to 6 inches thick Cartridge filters – Viscous cube or pocket filters Throwaway – Synthetic media panel filters 50-70 25-30 35-50 20-35 > 10 μm Pollen Dust mites Cockroach body parts and droppings Spanish moss Sanding dust Spray paint dust Textile fibers Carpet fibers Minimum filtration Residential window air conditioners Throwaway – Fiberglass or synthetic media panel, 1 inch thick Washable – Aluminum mesh, foam rubber panel Electrostatic – Self-charging (passive) woven polycarbonate panel
(Table Data Source – United States Environmental Protection Agency)
Who Uses MERV Ratings?
How is an Air Cleaner’s MERV Rating Determined? What Does an Air Cleaner’s MERV Rating Mean for You?
Sources referred to in this article:
- Mechanical Reps., Inc. “MERV Rating Chart.” http://www.mechreps.com/PDF/Merv_Rating_Chart.pdf
- National Air Filtration Association. “Understanding MERV: NAFA User’s Guide for ANSI/ASHRAE Standard 52.2-2007.” http://www.nafahq.org/LibaryFiles/Articles/Article006.htm
- Newell, Donald A. “Interpreting Filter Performance.” http://www.emcorservicesnynj.com/news/FilterPerformanceByDN.pdf
- United States Environmental Protection Agency. “Guide to Air Cleaners in the Home.” http://www.epa.gov/iaq/pubs/airclean.html
- Wikipedia. “Minimum Efficiency Reporting Value.” http://en.wikipedia.org/wiki/Minimum_Efficiency_Reporting_Value
- Wilkinson, Ron. MC2 “Market & Competitive Convergence — Air Filters: New Facilities, New Standard.” http://www.foustco.com/_fileCabinet/ProductInstructions/HVACFilters/merv_explanation.pdf