Upgraded filter testing is the less comprehensive testing procedure, which includes two tests of an upgraded filter version in each of two test water salinities. The testing procedure is designed to verify equivalence between filters.
The tests are typically performed as comparison testing between the old and a new version of the filter. The filter comparison test normally includes analyses of water quality parameters and live organisms ≥50 µm. The ‘upgraded filter testing’ is required, when the filter manufacturer makes significant changes of the filter, such as mesh geometry, additional backwash suction-arm or a new and more compact design.