MERV and Its Effect on Mist Collection

In industrial mist collector applications, you have to be cautious about MERV ratings. MERV values are supposed to represent the “minimum efficiency” of the filter, but unfortunately, this testing procedure does not take into account what happens when a filter gets wet.

With any mist collector application, the filter is going to get wet. In most mist collectors today, some level of efficiency is going to be lost, at least to the primary filter. Here are some reasons why...

  • As the fibers in the filter media get wet, they move. Most filters do not have any type of binders that hold fibers in place. Therefore, when a filter gets wet, fibers can move, resulting in microscopic holes in the filter itself, reducing its overall efficiency.
  • If a filter media doesn’t drain well or is overloaded, the filter can become over saturated. When this occurs, collected mist can be stripped off the backside of the filter, making it appear that the mist is blowing straight through the filter.
  • Filters designed for dust or dry collection typically don’t have the proper structure or framework to handle wet applications. Filter frames, gaskets, fiber resins, and even some filter fibers are not designed to get wet; if they do, the filters may fall apart.

Before you purchase your next mist collector, contact your Trion Authorized Representative to assist you, to ensure that you are getting a mist collector that will properly handle your mist collection application.

MERV Facts

  • MERV does not correspond to mist collection efficiency. As filters get wet, they typically loose efficiency.
  • MERV testing is done only with a test dust, not a test liquid.
  • A higher or lower MERV does not equate to filter life. Mist filters must be able to drain collected mist if they are to provide any significant filter life
  • If a high MERV is needed for safety or to handle smoke, use a good primary filter that will filter most of the mist as well as drain, and then complete your system with a final filter such as a 95% DOP or HEPA filter.