Does a sudden drop in pressure across the filter indicate damage rather than improvement?

Does a sudden drop in pressure across the filter indicate damage rather than improvement?

How a system behaves when its filters change is decided by that system, and the label sets the filter's own limits.

The NanoFlashing™ Air Filter label sets the filter's replacement point at the pressure drop printed on the product, or at the interval printed on it, whichever comes first. It also directs: “Do not install a filter whose media is torn, crushed, wet or visibly damaged.” and “Check that the filter sits square in the track with no gap at the frame. Air that passes around a filter is not treated by it.”

A reading taken across an installed filter is read by the people who run that system, against the system's own commissioning record.

Source: NanoFlashing™ Air Filter label, Directions for Use and About this product.

Reviewed on 21 September 2026.