Development of HEPA filter in China bio-safety laboratory
After 2008, the revised content of GB 1948-2008 (Draft for approval) was officially determined. With the support of science and technology support plan, major special project of infectious disease prevention and control science and technology, national key research and development plan project and other related science and technology plans, relevant scientific research institutions in China began to work hard on HEPA filtration device and key technologies, and officially entered the stage of science and technology innovation and development.
The shape of the sampling port of the filter scanning probe is generally square or rectangular, mostly rectangular. The scanning mechanism can use a single probe, but to carry out X-Y two-way movement, the motion control mechanism is more complex, which is mostly used by the factory filter test bench. Another way is to add multiple sampling probes to form a row, and the probe moves only in one direction. This mechanism is relatively simple, but it needs to use the probe automatic switching device or manual switching. Due to the small positioning range of the conventional rectangular sampling probe, the function of accurate positioning of the leakage point is highlighted. If the leakage point is found, the factory can repair it locally. However, in the field of biosafety, once the filter leakage is detected, even if the filter has been sterilized, it is not allowed to remove the filter for temporary repair and then use it again, which can not reflect the advantages of scanning leak detection, which is a precise positioning function. At the same time, this kind of scanning leak detector also has the problems of long working cycle and many matching instruments.
In order to solve the above problems, the national biological protection equipment engineering and technology research center has developed another type of scanning sampling probe, which is the same width as the air outlet of the filter, and the sampling port is a slit, in the shape of a line. It only needs to run from top to bottom once to complete the leak detection of the whole filter. According to its operation mode, it can be called the line scanning method. In 2009, the leak point identification ability of the line scan leak detection device passed the inspection of the national construction engineering quality supervision and inspection center. The results show that the line scan leak detection device can accurately identify and locate the leak point (artificial pinhole leak point), as shown in Figure 1, the three leak points are respectively located near the frame of the filter, 1 / 4 position and the middle position.
