Importance of MERV

MERV stands for Minimum Efficiency Reporting Value. It’s a testing and rating system developed by the American Society of Heating, Refrigerating and Air-conditioning Engineers (ASHRAE) for comparing the efficiency of media filters, bags, and cartridges. It specifically looks at the efficiency of the filter on particles in three size ranges: 0.3 to 1 micron, 1 to 3 micron, and 3 to 10 micron. Prior to MERV, industries used different measures of efficiency and different testing protocols, which lead to confusion as to what actual efficiency is.

The question that should be ask is not what is MERV, but how does it benefit my application?

Typical industrial filtration systems use filters that range from MERV 8 to MERV 15, not including polishing/final filters such as HEPAs. The higher the MERV number, the higher the efficiency of the filter. What happens too often is customers are sold that a higher MERV value is better, but that isn’t always true. MERV has nothing to do with filter life, nor maintenance cycles, not even how clean the air is after the filters.

It’s important to work with an expert who can determine what type of filter system is best for your application. To find an expert who can assist you in solving your filtration needs, contact your local Trion Representative today.

MERV Facts

  • MERV: Minimum Efficiency Reporting Value
  • Although a higher MERV typically represents a more efficient filter, it does not necessarily mean a higher MERV will provide higher efficiency for your specific need. You wouldn’t use mosquito netting to catch a fish, so why use a HEPA filter to capture dust from cutting granite?
  • MERV is based on laboratory dust, a specific airflow or velocity through the filter, and tested in laboratory settings. Don’t be surprised if your filter gets higher or lower efficiency. Laboratory testing does not matches actual real world settings.
  • MERV can be tested at one of 7 air velocities. When comparing two different filters, ensure you know at what velocity each filter was tested at. For example, efficiency at 118 feet per minute may be significantly higher than the same filter tested at 748 feet per minute.
  • Most filters are at their minimum efficiency when new. Adding dust to a filter typically increases its MERV rating.
  • There is no comparison between MERV and the life of a filter.