What are the causes of unqualified high efficiency air filter detection in Shanghai?

High efficiency air filter

There are three reasons for unqualified high efficiency air filters, so what are the three? Here’s how. Analysis from the wind speed of high efficiency air filter detection of unqualified factors is a very important factor affecting the filter effect of high efficiency air filter, the higher the wind speed of filtration efficiency, the filter material itself because of low efficiency. If the efficiency of the filter material itself does not meet the requirements (the definition of high efficiency filter material: detection at 5.3cm/s wind speed, for 0.3μm dust filtration efficiency ≥99.97%), it will not be able to produce a qualified filter.

If only a few local damage and not serious, it is possible to repair qualified products, but the repair quality should meet the standard requirements. Seal defects, air leakage in the combination of filter material and filter frame. In production inspection, most efficiency disqualification is caused by such air leakage.

Most of these cases can be repaired, but the repaired appearance should not have obvious defects. There is air leakage in the joint of the filter sealing rubber strip.

Many HEPA filters have sealing strips on the border. Sometimes, the interface is not handled well, resulting in air leakage. Some manufacturers use on-site foaming polyurethane seals, no seams, there is no air leakage problem. (Shanghai high efficiency air filter manufacturer)

If a joint is used, the joint is best made into a maze. This truth who all understand, but the market does indicate that some is efficient, the actual can not reach the efficient filter material. Materials dust.

Traditional partition high efficiency filter, if the paper partition, and the raw material control is not strict, the paper partition has the risk of dust. Filter material production environment is poor, filter material itself with a large number of dust may fall off, the filter may also dust. (Shanghai high efficiency air filter manufacturer)

It is important to note that some tests cannot detect such dust.

During factory inspection, if scanning detection method is used, there may be eddy current on the outlet surface of the filter, and the surrounding dust will enter the scanning area with the eddy current.

If eddies exist, dust will certainly exceed the standard during the scan. At this point, you cannot determine whether the dust is from the filter leak or vortex, and inexperienced operators may judge a good filter as a waste. Some foreign manufacturers, in order to eliminate the misjudgment caused by eddy current, put the filter test table in the clean room. Domestic manufacturers don’t have that luxury, so we have to find ways to eliminate turbulence. In the early summer of 2004, I came across a case in Beijing. (Shanghai high efficiency air filter manufacturer)

The end customer is a famous key laboratory, which requires the engineering contract to test the filter one by one before installation. The contractor built a simple scan bench, and the filter failed every test.

After we explained that they also suspected eddy current, they covered the air outlet side of the filter with a long pipe, which was increased to 1m in length, and eddy current still existed. When the filter is installed, it is sometimes scanned on site. That is the responsibility of the installation company or the user, but the high air filter manufacturer is often required to participate. At this point, vortex is also a headache, a little careless, may also be good filter waste.

In many cases, after the filter is installed, people use the downstream dust concentration to judge whether the air filter is qualified. At this time, if the upstream concentration is too large, even if the filter efficiency is qualified, it may be misjudged as unqualified due to the high downstream concentration. Sealing problem of HEPA filter Sometimes, the sealing of the contact part of the HEPA filter and the external structure is not strict, resulting in leakage.

This is not the quality of the filter itself, but the external structure or installation problem. Field installers sometimes plug glue around the HEPA filter. I don’t like the glue plugging method, because practice has shown that once the contact part is not sealed well, the more glue plugging it, the more leakage, you may never plug tight.

The sealing of the filter should be guaranteed by the sealing structure itself. If the structure is not good, the structural defects should be dealt with