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Trial calculation formula for surface air velocity and filter speed of high efficiency filters
Trial calculation formula for surface air velocity and filter speed of high efficiency filtersThe followings are the formulae and meanings related to the filter speed and efficiency of high-efficiency filters.Q - air volume (m3/h) F - high-efficiency filter cross-sectional area, i.e. windward area f - a net area of filter media, i.e. the area occupied by the removal of bonding, etc. Resistance: The fibers make the airflow around, creating a small resistance. The sum of the resistance of countless fibers is the resistance of the high-efficiency filter. High-efficiency filter resistance increases with the increase in air flow, by increasing the area of air filter material, the relative air speed through the filter material can be reduced to reduce the high-efficiency filter resistance. Surface air velocity (u): the speed of the airflow through the cross-section of the high-efficiency filter (m/s) u = Q/(F×3600) Description: In the case of constant air volume, the larger the filter area, the smaller the surface air velocity u Filter velocity (v): velocity of airflow through the filter media area (m/s) v = 0.028 x Q/f Explanation: The larger the net area of the filter media, the lower the filter speed and thus the better the filtration efficiency can be achieved, provided that the air volume remains unchanged. Under certain conditions of the HEPA filter construction, the nominal air flow rate is the uniform reflection of the surface speed and the filter speed. At the same cross-sectional area, it is expected that the higher the rated airflow is, the better, while operating below the rated airflow, the filter speed of the HEPA filter decreases, the filtration efficiency increases and the resistance decreases. |
