The Clean Air Delivery Rate - CADR explained!

What does the CADR Level actually tell us?

CADR briefly:
The CADR (Clean Air Delivery Rate) is a Measurement that indicates how well the Air Purifier has conditioned the Air. It helps to compare the Effectiveness of different Devices that are offered on the Market. In a nutshell, the higher the CADR Level, the more efficient the Product is.

CADR is a Value that measures the Air that has been cleaned by the Air Purifier. This Value is determined by practical Tests of the various Devices in a standardized Room. This standardized Room is 28.5 m³ and manages to accommodate almost a lying Soccer Goal in itself

Fig. 1 A standardized Room with a Size of 28.5m³.

First, this Type of Room is cleaned very thoroughly before the Product Test and is then filled with a Specific Type of Particles in each case. Afterwards, the amount of Particles that were not filtered by the Device is measured during the respective Tests and later subtracted from the originally supplied Value. This allows the CADR Value to be calculated. This represents the most accurate Method to determine the different Air Purification Products Products directly with each other. Aspects such as the Performance of the Air Purifier, the varying Size of the Vents, and the Filters installed in the Device play an important role during the Tests, but in general, the higher the CADR Value, the better the Device. However, not all Particles that contribute to Air Pollution are the same Size, which is why the Test must distinguish between Smoke, Dust and Pollen Particles and examine them separately from each other. Smoke Particles have a Size of approximately 0.09 - 1.0 Micrometers, Dust Particles have a Size of 0.5 - 3 Micrometers and Pollen Particles are in the Range of 5.0 - 11 Micrometers.

Fig. 2 Illustration of Particle Size

Despite the different Sizes of the Particles, although it seems only logical that large Particles can be filtered more easily, the Rate of Filtered Particles often turns out to be the same. This is due to the fact that larger Particles, such as Dust or Pollen Particles, are heavier due to their Size and can therefore adhere to Surfaces and Walls more easily. To provide better Filtration of small Particles, slower rotating Fans are often used. Since a slow intake Speed in turn gives the large Particles more time to settle on Surfaces, however, the "low" Filtration Level of large Particles Results in all the better Filtration of small Particles. When and why a HEPA-Filter or an ETA Filter is sufficient, it is here further explained

Pro Tip: The CADR Rating measures only the Efficiency of the Product and the Noise/Disturbance is not a Factor in this. Depending on where the Product is used, you may be able to reduce annoying Noises by purchasing a larger Product that runs at a lower Level. 

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