What is Merv?

What is Merv?


MERV filter rating is the air filtration industry's standard for measuring and reporting how efficient air filters, like our replacement cartridge filters, are. In other words, it is an air filter rating of a filter's Minimum Efficiency Reporting Value. Because removing particles from the air is the primary function of an air filter, the MERV ratings (most filters are labeled) indicates the measured ability of that filter to trap particles that range in size from 3-10 microns. Noting that a particle of 10 microns is not visible to the naked eye, for reference consider that pollen ranges between 5-100 microns and human hair between 70-100 microns.

While residential air filters most commonly have MERV ratings between 1 and 12, industrial air filter ratings are usually between 6 and 15. As you might already know, the higher the MERV filter rating the more efficient the filter is, and the more particles it can filter from the air. Some industrial air filtration applications, like welding and grinding, require the use of higher efficiency filters with better MERV ratings in order to capture process particles that have been proven to be dangerous to workers. The standardization of measurements and air filter ratings allows for an easy way for consumers to compare filters made by different manufacturers. Just for comparison, below is a table translating a few MERV ratings into easier to understand percentages of air filtration or particle capture:

MERV Rating Efficiency
6 35-50% minimally efficient at capturing measured particles
8 70-85% minimally efficient at capturing measured particles
11 85-95% minimally efficient at capturing measured particles
15 99.97% minimally efficient at capturing measured particles

At Industrial Maid, our units are designed for a variety of styles and configurations to allow for total customization of filter capacity. In standard units we use combinations of 4 basic filter types; polyester pre-filter media, pleats (MERV filter 6-8), bags (MERV filter 12-14), and HEPAs (MERV filter 15).

For example, an application where odor is the issue, the solution might be as uncomplicated as our AZTech 2000C that has a 4" pleated pre-filter, a 95% bag and a final 2" carbon adsorption filter. The AZTech Model 2500 includes a main interior filter assembly with a 95% efficient 65sq ft filter bag and a 10sq ft wrap around 2-1/2" polyester pre-filter which is perfect for applications where easy change out of filters is a priority.

A very popular add-on for our T-Series is the "Filter Saver" option. A 2" poly pad mounted on hangers that is very easy to take off and replace, serves as an additional pre-filter, that extends the lifespan of interior filters.

For an example of more complex design take a look at our RH36VX2. It has a three stage fume extraction filter system that includes a baffle filter, 4” pleated filter (Merv 7) and a 95% multi-pocket main bag filter (Merv 13). These filters will handle oily welding smoke, and options are available to include a final HEPA filter for stainless steel fume or other applications requiring higher efficiency filtration. As you can see in the above table, the high MERV air filter rating for a HEPA filter is based on it's ability to capture nearly all microns .3 in size, verses .1 or even .001. Microns of .3 are the hardest size to trap and the optimal size for passing into the respiratory system of a human . Therefore the .3 micron efficiency rating sets the highest standard. A HEPA filter is so efficient that for every 10,000 particles that enter the filter within its filtering range, only 3 particles will get through.

These are just a few of the filters that Industrial Maid uses to make the industry's most efficient and versatile industrial air cleaning systems. Many more types of filters with a variety of air filter ratings are available for a variety of special applications. Just give us a call at TF: 1-877-624-3247 if you would like to visit with one of our engineers about what type of filter would best suit your needs.

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