Proposes revisions to Section 5.16.1. The reference filter check in the current standard is not practical. The shape of the filtration efficiency curve is somewhat S-shaped, and the present criteria are not applicable for such shapes. By proposing that the shift be measured on the filtration efficiency axis, the addendum makes the specification applicable in all cases. It also allows a wider selection of filters so it is easier for testing laboratories to locate reference filters.
ANSI/ASHRAE 52.2a-2006 history
2006ANSI/ASHRAE 52.2a-2006 Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size