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What are the factors that affect the filtration efficiency of air filters?

Air filter filtration efficiency is a key concern when purchasing air filters, and filtration efficiency affect the choice of products purchased as well as later production efficiency and the environment.
Since filtration efficiency is so important, what are the factors that affect the filtration efficiency of air filters?

1, filter bag material: The choice and application of filter bag material is the core technology of bag-type dust collection equipment, which plays a decision-making role in the performance of high-efficiency air filter dust collectors.
Because of the environment of each dust collection point, the nature of the processing dust, temperature, and technical requirements are not the same, so choose different filter materials for different conditions, and take the appropriate technical care measures.
The requirements of the filter bag material contain the following technical performance: filter bag material for different temperatures, peel good, easy to clear ash, good permeability, low resistance, high filtration efficiency, high strength, can withstand high strength ash cleaning, long service life, suitable price.

2, the impact of filtration wind speed: wind speed to increase resistance, wind speed to reduce resistance to reduce. For inertial motion-based large particles, wind speed, and the inertia of particles increased, and the possibility of impacting obstacles increased, so the filtration efficiency increased.
However, the inertia is large, and the rebound force of the obstacle on the particles also increases, if the van der Waals force can not overcome the rebound force, the particles will run away, therefore, sometimes increasing the air speed, the filter efficiency of large particles is reduced instead. For small particles mainly diffusion movement, the filtration efficiency depends on the retention time of the particles in the filter media, the retention time is shortened (increase the airspeed), the chances of the particles hitting the obstacles are reduced, and the lower the filtration efficiency.
If the material is electrostatically charged, the filtration efficiency depends on the retention time of the airflow in the material. The lower the filtration air velocity, the higher the filtration efficiency, for both large and small particles.
Electrostatically charged materials are particularly sensitive to filtration air velocity. For example, when measured at 1 cm/s, the permeability of 0.3 μm dust is 0.01% (99.99% filtration efficiency), while when the filtration airspeed is increased to 5.3 cm/s, the permeability is 1.5% (only 98.5% filtration efficiency).

3, the impact of humidity: In general, changing the humidity will not affect the efficiency and resistance of the air filter.
However, when the air humidity is very high, the filter media may condense, and there is a water film on the contact surface of the particles and obstacles, the contact surface between the two is larger, the bonding force is also larger, and the large particles are no longer so simple to bounce, so the filtration efficiency of large particles may be improved.
In reality, the performance of a filter may change in a variety of unpredictable ways if it is wet enough to carry water. For example, with filter paper made from vegetable fibers, if the paper has poor water resistance and water softens the paper, the fibers compress and the resistance of the filter can increase rapidly until the filter is blocked.
Another example is a high-efficiency filter with water, the dust will be transported by water to the back wind side of the material after the wind dries, and the filter becomes a hair duster.

4. Air leakage directly affects the dust collection effect and life of the dust collector, requiring an air leakage rate of <3%. Bag-type dust collector generally has negative pressure operation, such as air leakage easy to forms a small circuit short circuit.
The dust collection system does not handle enough air and forms positive-pressure dust. Air leakage also lowers the system temperature, makes it easier for the bags to be damped, increases dust collection resistance, and reduces the filtering effect of the air filter equipment.