For a clean room in operation, the value of the end high-efficiency filter is not high, and the total value may not be less than the user's output value in a few hours, but the risk and indirect cost of replacing the end high-efficiency filter will be high. When replacing the filter, the production must be stopped. Only the owner can calculate the loss of the stoppage. This loss must be higher than the cost of spare parts for the filter. Replacing the high-efficiency filter is a very careful operation. Anything in the clean room may be expensive, and the damage to a component may be higher than the cost of the entire filter. After replacing the filter, it must be tested by a professional, and sometimes the air conditioning system must be debugged, and a period of trial operation is required. The three costs of inspection, debugging and trial operation are added together, which may be comparable to the price of the filter. Smart owners always want to extend the life of high-efficiency filters as much as possible, not to save a few dollars on the filters, they want to avoid a bunch of troubles caused by replacing the filters.
To extend the service life of high-efficiency filters, the most fundamental way is to block dust in the pre-filter. Replacing the pre-filter generally does not need to stop production or commissioning, so experienced owners will spend their attention and money on pre-filters and protection-level intermediate filters. For 10K and 100K clean workshops, G4 is used for pre-filtration, and F8 filter (95% colorimetric method) can be used for intermediate filtration. In this way, the service life of the end high-efficiency filter can generally reach 5 years. In foreign projects and new domestic projects, F8 filter is the most common pre-filter in non-uniform flow clean room.
In some cases, the regulations on the service life of high-efficiency filters are not based on resistance considerations, but on other factors. If there is hydrofluoric acid in the plant, and the air conditioning in the workshop is not a new air system, the glass fiber filter paper in the high-efficiency filter will be corroded by the return air. For safety, the high-efficiency filter must be replaced regularly. Some large pharmaceutical factories need to replace high-efficiency filters after the rainy season every year, in order to prevent any possible mold contamination on the filters. Some biological laboratories and laboratories dealing with dangerous goods will require the use of new high-efficiency filters for reliability before launching a new important subject.