The service life of HEPA filter is related to the air inlet volume of air conditioning box. Our company has built a factory for more than 10 years, and the service life of the high efficiency filter in the early plant is generally 5 years. At the beginning of 2001, a new workshop was put into operation. After more than two years, the resistance of the high-efficiency filter reached more than 650Pa, and the filter was scrapped. We found that the design air volume of 1220x610mm high-efficiency filter in that workshop was 3150m³/h. It is much higher than other workshops of our company.
The service life of the filter is also related to the air supply quality of the air conditioning box. It is also the factory C mentioned in the previous case. Less than 100 meters north of the factory building, a large factory building 400 meters long and 50 meters wide is under civil construction. The weather in autumn, winter and early spring is dry, and the north wind often blows. The sand dust raised by the wind directly splashes on Plant C. The primary filter on the air conditioning box in plant C was blocked after less than half a month of use. However, the replacement cycle of the filter in the air conditioning box of plant D, which is far from plant C, is normal.At that time, it was thought that the dust holding capacity of the filter used in plant C was low.We observed the filter materials with a microscope and found that the size of dust particles accumulated on the filters in plant C and plant D was different. The diameter of particles on the filters replaced by plant C was significantly larger. The air conditioner in Plant C inhales more dust, so the service life of the filter is certainly short.
Forklifts need to be used in plant E. At the initial stage, diesel powered forklifts were used because of their high power. But these diesel forklifts also cause problems with the filter. Incomplete combustion of multi carbon oxides is dispersed in the air, enters the air conditioning box through the return air, and condenses on the filter. We observed with a high power microscope and found that the condensate was in a semi flowing state on the primary and medium efficiency filters. Those agglomerates may migrate to the back of the filter material and volatilize due to uneven heating and humidification of the air, enter the HEPA filter downstream, and aggravate the blocking of the HEPA filter. Later, Factory E changed to use electric forklifts, which reduced the chemical pollution in the plant and also alleviated the filter blockage.
