The dust holding capacity of ultra high efficiency air filter refers to the maximum allowable dust accumulation of the filter: when the dust accumulation exceeds this value, the filter resistance will increase and the filtration efficiency will decrease. Therefore, generally, the dust capacity of the filter refers to the dust capacity when the resistance due to dust accumulation reaches the specified value (generally twice the initial resistance) under the action of a certain air volume.
The increase of resistance after dust accumulation of the filter is related to the size of solid dust particles. After the dust is deposited on the filter, the impact on its efficiency is very complex. Under a certain wind speed, it depends on the nature of the filter material and the nature and size of dust particles. For example, the air filter paper composed of general fiber material increases the contact retention effect of the filter due to the dust accumulation of the filter material. At the same time, due to the charging effect of the dust particles, other dust particles accumulate on the blocked dust particles, so as to improve the filtration efficiency of the filter; However, when the dust accumulates to a certain limit, the accumulated dust will fly away, or the filter material will be broken down due to the excessive pressure difference on both sides of the filter material, resulting in a serious decline in the efficiency of the filter.
According to the parameters of the rated dust capacity of the air filter, theservice life of the ultra-high efficiency air filtercan be calculated. The service life of air filter generally takes the time to reach the rated dust capacity as the service life of the filter.
The service life of air filter is related to the amount of dust generated by indoor dust source, the dust particles carried by personnel and the concentration of atmospheric dust particles. In the case of air pollution in most central cities in China, the service life of ultra-high efficiency air filter generally used in clean room is about 3 months.