MERV Explained

Filter ArrayFilters are an integral part of a welding fume control system. The purpose of the filter is to capture and remove airborne particulates from the workplace environment. Welding fumes are comprised of complex metallic oxides, often along with silicates and fluoride compounds, forming particles that are typically less than 5 microns (µm) in diameter. Whether it is a single extraction unit like the X-Tractor® Mini, a large multi-arm central system or a plant-wide general filtration system, filters play an important role.   

Here are some key facts to remember:

  • The ability of a filter to remove particulate from the extracted welding or plasma cutting fume is expressed as its Minimum Efficiency Report Value or MERV.
  • The MERV scale is 1 to 16.
  • MERV is determined by testing the filter using ANSI/ASHRAE Standard 52.2-2017 "Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size."
  • Each MERV specifies an efficiency level for three particle size ranges.
  • Example MERV parameters (Composite Average Particle Size Efficiency, % in Size Range):
MERV Chart.png 
  • Filters with a HEPA designation (High Efficiency Particulate Air) have efficiency levels above MERV 16.

When the fume extraction system indicates it's time to replace the filter(s), do so in a timely manner to avoid degradation in extraction capacity. Make note of the spent filters' MERV when ordering replacements and use Lincoln Electric genuine filters for optimal system performance.