1. The willow catkins in spring are a disaster for the filter. The floating catkins block any air filter that tries to intercept them. In this case, you should take corresponding measures in the air conditioning design, such as changing the height of the air inlet or adding protective nets or frequently replacing the filter at the air inlet.
2. Mist is a small water droplet that touches the filter and mixes with the accumulated dust on the filter material to form mud. If the filter material is very fluffy, the mud will enter the downwind end of the filter with the wind, and the filter can still function properly. If the filter material is dense or water absorption becomes soft, mud will stick the filter to death. For filtration or dust removal devices with pulse back blowing cleaning function, if there is mud on the filter material, the cleaning function will fail. Some filters may not be afraid of continuous rain or rain. But afraid of continuous fog. On cloudy and rainy days, there is less dust, and even slight measures can keep rainwater out of the filter. There is no shortage of dust in foggy weather, and no measure can stop the fog.
3. In the cold weather of the north, there is often a phenomenon of fine rain falling on the ground and thin ice. Usually, filters block the fine rain as particulate matter, and water droplets freeze on the filter material below zero degrees Celsius and quickly seal the filter. Most inefficient filters can last for a while. When the filter material is dense filter paper, an hour is enough to freeze the filter to death. If there is a possibility of ice rain in your area, it is recommended to keep a set of filter spare parts, For emergency use.
4. Hydrofluoric acid has a strong corrosive effect on glass. The filter material of high-efficiency filters is often fiberglass, but some clean factories may produce hydrofluoric acid, which is feared by high-efficiency filters. For example, in the manufacturing process of a picture tube, the glass casing needs to be cleaned with hydrofluoric acid, and the cleaning process needs to be carried out in a clean workshop equipped with high-efficiency filters. Although hydrogen fluoride in the air can damage the fiberglass material in high-efficiency filters. Some "screen cleaning" workshops use fresh air systems, but in order to save energy, other designs use a large amount of circulating air. For the latter, the glass fibers in the high-efficiency filter become the "fuse" of hydrogen fluoride. The screen cleaning workshop with circulating air has inevitably encountered the problem of high-efficiency filters being corroded, sometimes even causing malignant accidents. When high-efficiency filters have to come into contact with hydrogen fluoride, the final resistance is no longer the basis for judging the service life of the filter, and managers should mandatorily specify the replacement cycle of the filter. The new high-efficiency filter material PTFE is not afraid of hydrogen fluoride, but if it is used in the above situations, it is equivalent to replacing the "fuse" with copper wire.