Does a rating describe the lowest efficiency over a particle range or an average?

Does a rating describe the lowest efficiency over a particle range or an average?

The two ratings the company publishes are built differently, and their names say so.

MERV is the minimum efficiency reporting value under ANSI/ASHRAE Standard 52.2. It is built from the lowest efficiencies the filter reaches in each particle size range as dust is loaded during the test, not from a single reading on a clean filter. An ISO 16890 class rates a filter against a particle fraction, ePM1, ePM2.5 or ePM10, and the class the filter holds is the one the certificate states. As the company's Validation page puts it, industry standards ASHRAE 52.2 Appendix J and ISO 16890 test electrostatic filters after their temporary charge is removed, showing how they perform without it. Neither rating is a single number describing a whole filter in a building, and neither converts into the other. Certificate No. 15.06.011 covers a ten-pocket bag filter, not a flat panel filter, and Report 6847 is on a 24 × 24 × 30 in. pocket filter; a rating belongs to the construction that was tested. Certificate No. 15.06.011 can be looked up at source in the Eurovent Certita Certification certified product directory.

Source: ANSI/ASHRAE Standard 52.2, as named in LMS Technologies, Report LMS#9904, 28 April 2025, a single-pass fractional efficiency test on a 24 × 24 × 2 in. pleated air filter in an ASHRAE 52.2 test duct, in accordance with standard LMS aerosol test procedures, and Report 6847, ASHRAE 52.2 with Appendix J; ISO 16890, as named in Eurovent Certita Certification Certificate No. 15.06.011; C-POLAR — Validation, https://cpolar.tech/validation/; Eurovent Certita Certification certified product directory, read 19 September 2026, https://www.eurovent-certification.com/. A copy may be made available on our review of the request.

Reviewed on 21 September 2026.