The Ultimate Guide To Air Filter MERV Ratings

The Ultimate Guide To Air Filter MERV Ratings

There are several different kinds of MERV rating filters, and in this article, we will talk about each one of them. For an average user, knowing the differences between MERV ratings is not a common thing, but actually, it’s nothing complicated to understand. Like most other things in life, with air filters and MERV ratings, there are some ground rules to follow and essential things to know, and you’re good to go. We will start from the very beginning by explaining the scales.

What Is a MERV Rating?

Minimum Efficiency Reporting Value (MERV) rating is a measurement scale created in 1987 by American Society of Heating, Refrigerating and Air-Conditioning Engineers to rate air filters and their effectiveness. The MERV scale was designed to represent the worst-case performance of filters when dealing with particles ranging from 0.3 up to 10 micrometres. The MERV rating goes from 1 to 16. The higher the MERV rating is, it means it corresponds to a higher percentage of particles captured on each pass, for example, a MERV 16 filter will capture more than 95% particles.

Everything You Should Know About AQI

An Air Quality Index (AQI) is a number used by the government agencies to let the public know about the quality of the air and how much polluted it is currently, as well as forecasting how polluted it will be in the future. With the increase of the air quality index, it is likely that a significant percentage of the population will experience an increase in severe health issues and effects. Therefore, to avoid the polluted air in your home or workplace, find the MERV rating filters you need and install them, while keeping them clean and changed when necessary.

MERV Rating And Particle Sizes Explained

There are several groups of MERV rating filters, and each one of them has the minimum particle size that will not be allowed to pass. I will explain further which the typically controlled contaminants are, and the typical places of application as well as air quality index involvement:

MERV 1-4 rating is for particles bigger than 10 micrometres like pollen, dust mites, sanding dust, cockroach debris, spray paint dust, textile and carpet fibres. MERV 1-4 rating filters are commonly placed on residential window AC units.

MERV 5-8 rating is for particles ranging from 10 micrometres up to 3 micrometres like mould, spores, dust mite debris, fabric protector, cat and dog dander, hair spray, pudding mix, and dusting aids. A typical application of filters is recommended for average households and industrial workspaces.

The Ultimate Guide To Air Filter MERV Ratings

MERV 9-12 rating is for particles in the range from 3 up to 1 micrometre like lead dust, milled flour, auto emission particles, legionella, humidifier dust, nebulizer droplets. Typical application places for MERV 10 rating air filters are recommended for households with infants, while MERV 11 is supported for pet owners, and furthermore to hospital laboratories.

MERV 13-16 rating is for the particles of significantly smaller size ranging from 1 to 0.3 micrometres. This kind of air filtration is needed in hospitals for general surgery. MERV filters from this group will keep out the bacteria, cooking oil, most smoke and insecticide dust, droplet nuclei (sneeze), most paint pigments, and most face powder. MERV 3 is recommended for people suffering from allergies.

MERV 17-20 rating is for the particles that are smaller than 0.3 micrometres like viruses, carbon dust, smoke, and sea salt. These filters are typically applied in pharmaceutical manufacturing clean rooms.

The smallest MERV value in each group doesn’t have the minimal requirement for filtration of that group’s particle size, but it does have strict requirements for all larger particle sizes than any smaller MERV value. For example, MERV 8 has no minimum standards for the removal of 3.0 to 1.0 micrometres particles, but MERV 8 has a higher minimum requirement for removing 10.0 to 3.0, and > 10.0 size particles than MERV 11 and all other smaller MERV groups has. All other MERV values from each group do have a minimal removal percentage for the group’s particle size.

All MERV filters including MERV 8, 10, 11, and 13 have various shapes and sizes to choose from. Mostly, around 20 sizes are ranging from 10×10 inch up to 25×25 inches while all of them being 1-inch-thick. Same goes with 2-inch-thick filters that have approximately 20 different sizes to choose from. People are also able to give the details about the size they need and order their own, custom-sized filters.

With all said, we concluded that first of all, you should know what kind of pollution you are up against. Secondly, you need to determine whether your home or workplace already have MERV filters installed and are those filters adequate for the contamination at hand. In case you are not familiar with MERV ratings and filtration in general, get into contact with professionals, give them all the details you have, and they will for sure place and install the correct kind of filters in your home.

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