For many years, all of the tests used the ASHRAE 52.1, and it was able to provide the efficiency rating with some accuracy. However, the test was not flawless, and that’s why there is now the new test, the ASHRAE 52.2, which is going to offer better and more accurate testing. The particle range sizes in the new test have different ranges and groupings, as well as different MERV parameters They get the results from the tests by using a clean filter for the first run and then reusing that filter for another 5 times.
The ASHRAE 52.2 Test Standard: MERV 7 covers values from 3 to 10 microns and is effective for between 50% and 70%. The MERV 8 test is effective at 70% for the same particulate size of 3 to 10 microns. The filters used here are usually pleated filters or tackified filters. They are useful in a variety of different areas including commercial practices, industrial work, paint booths, and more.