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How to judge whether the qualified high-efficiency filter
How to judge whether the qualified high-efficiency filterDue to the strict requirements of the place of use, high-efficiency filters must be tested unit by unit before leaving the factory and pass the standards before being put into use. The testing of filters includes factory testing and field testing. During these two tests, the reasons for filter failure may be as follows.High-efficiency filter I. Reason of raw material itself (1) Low efficiency of the filter material itself. If the efficiency of the filter material itself cannot meet the requirements (definition of high-efficiency filter material: tested at 5.3cm/s wind speed, filtering efficiency of 0.3μm dust ≥ 99.97%), it is impossible to produce qualified filters. This principle is clear to everyone, but some of the markets marked high efficiency but not up to the high efficiency of the filter material. (2) Material dust. Traditionally, there is a high-efficiency filter with a partition. If the paper spacer is not strictly controlled, the paper spacer has the danger of dust. Filter materials are produced in a poor environment. The filter material itself carries a lot of dust and may shed. The resulting filter may also generate dust. It is worth noting that some testing methods cannot detect this dust. II. Problems with the test itself. (1) If a scanning test method is used during factory inspection, there may be eddy currents on the outlet surface of the filter, and the surrounding dust enters the scanning area with the eddy currents. If eddy currents exist, the dust must exceed the standard when scanning. At this point, you cannot be sure if the dust is coming from the filter nozzle leakage point or the eddy current. An inexperienced operator may judge a good filter to be a waste. Some foreign manufacturers place filter test benches in clean rooms to eliminate the misjudgment caused by eddy currents. Domestic quarrels are not so extravagant, so we must take steps to eliminate eddy currents. (2) In many cases, after installing a filter, people use the dust concentration downstream to judge whether the filter is qualified. Even if the efficiency of the filter is qualified, it may be misjudged as unqualified because of the high downstream concentration. III. Visual inspection and simple tests can identify the cause. (1) The surface of the filter material is broken or slightly damaged. It is easier to observe the damage to the filter material with the naked eye, and it is easier to repair a small amount of damage, preferably in the filter plant. Some minor breakage is not easy to observe and can only be detected after testing. (2) The filter material is too heavy in the production process, or some human factors will damage the filter material. If only a few places are damaged and not serious, it is possible to repair qualified products, but the repair quality should meet the standard requirements. (3) Sealing defects, and air leakage between the filter material and the outer frame of the filter. In the production inspection, most of the failure rate is caused by this kind of leakage. Most cases can be repaired, but there is no obvious defect in appearance after repair. (4) Filter air leakage at sealant joints. Many high-efficiency filters have sealant strips on the boundary. Sometimes the interface is not well handled and this can lead to air leakage. Some manufacturers use field-foamed polyurethane sealing strips with no joints and have no air leakage problems. If adhesive tape with joints is used, the joints should be labyrinthine. |
