What is the formula for calculating the filter speed and surface wind speed of the air filter?

Many people are asking me how the filtration speed of the air filter is generally calculated, and today I will sort it out for you.

The ability to measure the air volume of the air filter can be expressed by the surface wind speed or the filtration speed. The filtration speed reflects the passing capacity of the filter material, especially the filtration performance of the filter material. Obtain higher efficiency (this is because the particles are easier to stick to achieve the purpose of filtration under the condition of low filtration rate); and the lower the filtration rate allowed by the air filter, the greater the resistance of the air filter material.

Filtration speed and surface wind speed of air filter

The following are the formulas and meanings related to the filter speed and efficiency of the air filter:

Q—air volume (m3/h)

F—The cross-sectional area of ​​the air filter is the windward area

f—net area of ​​filter material, that is, the area occupied by the removal of bonding, etc.

Resistance: Fibers make air flow around, creating little resistance. The sum of the resistance of countless fibers is the resistance of the air filter. The resistance of the air filter increases with the increase of the air flow. By increasing the area of ​​the air filter material, the relative wind speed passing through the filter material can be reduced to reduce the resistance of the air filter.

After the air filter is installed

Surface wind speed (u): the speed of the air passing through the air filter section (m/s)

u = Q/(F×3600)

Note: In the case of a certain air volume, the larger the filter area, the smaller the surface wind speed u

Filtration velocity (v): the velocity of the air passing through the area of ​​the filter material (m/s)

v = 0.028×Q/f

Note: In the case of a certain air volume, the larger the net area of ​​the filter material, the lower the filtration speed, so that better filtration efficiency can be achieved.

Under the specific structural conditions of the air filter, the rated air volume is the unified reflection of the surface speed and the filter speed. Under the same cross-sectional area, it is hoped that the allowable rated air volume is as large as possible, and when the air volume is lower than the rated air volume, the filtration speed of the air filter will decrease, the filtration efficiency will be improved, and the resistance will be reduced.

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