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Testing the overall efficiency of an air cleaner.

Two criteria are required for an air cleaning system to be effective.

1. The filtration technology must be effective in the removal of the contamination present.
2. The airflow patters and volume created by the air cleaning system must cause the airborne contaminants to move rapidly toward the intake of the air cleaning device.

Too often, the wrong kind of or inadequate filtering media is used. Usually the efficiency is too low for the particles present. Or, the electronic system design does not provide maximum collection capabilities. Or, gas-phase, which is a major contaminant, is not addressed at all.

A realistic method to compare air cleaners overall efficiency is to use the CADR rating system (Clean Air Delivery Rate). The CADR is the product of the "net" air volume of an air cleaning system and the minimum filtration efficiency based on 0.3 micron standard.

Please find a comparison of competitive commercial air cleaners in the link below labeled AFTL Testing.

AFTL Testing

If you look at the first column: Trade Name-Miracle Air, you will see that the Claimed CFM (how much air the machine is moving) is 1100 and the claimed Particulate Filtration Efficiency is 95%. Below that you will see the actual results when the Miracle Air cleaner was tested: 550 CFM and the filter Particle Efficiency was 81.10%. If you multiply net CFM by Particle Efficiency at .3 microns, you get a CADR of 446 (0.811 x 550 = 446.05).

The actual performance of the air cleaner is well below the specifications advertised. This is common throughout all of the competitive air cleaners. This is because the Claimed CFM is what the motor is capable of producing without any filters in place. Once you put a filter in front of the motor, the actual CFM that the motor is able to pull through the filter dramatically decreases. To compensate, competitive air cleaners have to use less efficient filters to relieve resistance against the blower in an effort to get more airflow through their units.

If you look at the results of the Honeywell air cleaner, you will see that it moved even more CFM then it claimed and was 92.05% efficient at 0.3 microns, resulting in a CADR of 942. This is because Honeywell motors are custom engineered and selected to overcome the relatively high static pressure related to HEPA rated filters. Honeywell air cleaners have the highest CADR ratings economically feasible. Consequently, Honeywell air cleaners will clean the air in a given application with fewer air changes per hour than all other brands and types in its class.