Filtration

FILTRATION

Filtration is rated in increasing efficiency

Minimum Efficiency Reporting Value, commonly know as MERV rating is measurement scale designed in 1987 by the American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) to rate the effectiveness of air filters. For Example, a HEPA filter is often impractical in central HVAC systems due to the large pressure drop the dense filter materials causes. Experiments indicate that less obstructive medium-efficiency filters of MERV 7 to 13 are almost as effective as true HEPA filters at removing allergens, with much lower associated system and operating costs.

The scale is designed to represent the worst case performance of a filter when dealing with particles in the range of 0.3 to 10 micrometers. The MERV rating is from 1 to 16. Higher MERV ratings correspond to a greater percentage of particles captured on each pass, with a MERV 16 filter capturing more than 95% of particles over the full range.