High-efficiency air filters are generally used as filter tips. Therefore, the requirements for high-efficiency filters are also the most stringent. High efficiency filter as the end is the most critical level of all levels of filters, and requires an additional “view”. To extend the useful life of high-efficiency filters, the most fundamental way is to block the dust in the pre-filter. Replacement of pre-filtering generally does not require shutdowns or commissioning, so experienced owners will pay attention and money to pre-filters. For 10000 and 100,000 grade clean workshops. Pre-filtering can use F8 filter, so that the life of the end high efficiency filter is generally up to five years. In foreign projects and domestic new projects, F8 filters are the most common prefilters in non-uniform flow cleanrooms. For chip factory 100, 10 or higher cleanliness plants, the pre-filter common efficiency level is H10, many new projects simply choose HEPA. In the past domestic clean room air conditioning system design, filters are commonly configured as: coarse efficiency and efficient. At that time, the service life of high-efficiency filters was only 1 to 3 years, and the worst was only a few months. It can be seen that the efficiency of the prefilter determines the service life of the end filter.