(1)Usually, the last stage filter determines the degree of air purification.

(2)The upstream filters at all levels only have a protective effect and are collectively referred to as "pre filters".

(3)The efficiency of filters at all levels should be properly configured. If the efficiency specifications of adjacent filters differ too much, the previous level cannot protect the latter level; If the difference between the two levels is not significant, then the burden on the latter level is too small.

(4)The reasonable configuration is to set up a filter every 2-4 gears, according to the current filter efficiency classification in Europe. If the H13 high-efficiency filter is used at the end, the F5-F8-H10 three-way protection can be selected for the front stage, and the service life of the H13 high-efficiency filter at the end can reach up to eight years.

(5)The service life of the high-efficiency filter at the end of the clean room should be 5-15 years. The most important factors affecting the service life are the quality of the pre-filter itself and whether the configuration is reasonable.

(6)A filter with an efficiency of no less than F8 should be used to protect the high-efficiency filter at the end of the clean room.

(7)G3-F6 is a common primary filter in urban central air conditioning systems.

(8)Key points: The performance of the final filter should be reliable, the efficiency and configuration of the pre-filter should be reasonable, and the maintenance of the primary filter should be convenient.