With the continuous development of science and technology, the production of modern industrial products and modern scientific experiments have become more and more demanding for indoor air cleanliness, especially in microelectronics, medical, chemical, biological, food processing and other industries. The precision, high purity, high quality and high reliability of the indoor environment, the main way to achieve this goal is to widely use air filters in clean air conditioning systems. High-efficiency (HEPA) and ultra-efficient (ULPA) filters are the last protection for dust particles entering the clean room. Its performance is directly related to the clean room level, which in turn affects the process and product quality. To this end, many countries have developed and promulgated standards for performance testing methods: The US Military Commission established the military standard MIL-STD-282 in 1956, using the DOP (dioctyl phthalate) method, which uses forward light scattering. The photometric meter detects the turbidity ratio of the gas sample before and after the filter to calculate the filter efficiency of the filter. This standard has not been changed until now. In 1965, the British BS3928 standard adopted the sodium flame method. The detection instrument is flame luminosity. In 1973, the EUROVENT4/4 standard in Europe adopted this method; in 1985, China promulgated GB6166-85 "Experimental Methods for Performance of High-Efficiency Air Filters", using both the oil mist method and the sodium flame method as statutory performance test methods; Japanese Industrial Standard JISB 1 High Performance Filter Performance Test Method 1.1 Efficiency detection of high efficiency filter is known from the above. The efficiency detection methods of high-efficiency filters are various, but after more than half a century of development and evolution, the current influence is large and the scope of use is wide: DOP method, particle counting method and the most easy to penetrate particle size t (MPPS) )law. 1 DOP method refers to the heat generation (coagulation method) DOP aerosol plus photometer measurement method. The method was first proposed by the United States to heat the DOP liquid into a vapor. The vapor condenses into tiny droplets under certain conditions, and removes too large and too small droplets to leave a monodisperse phase aerosol particle of about 0.3"m. The DOP enters the air duct, and the turbidity ratio of the gas sample before and after the filter is detected by a light-scattering photometer to calculate the filter efficiency of the filter. 2 Particle counting method The particle counting method uses a particle counter as a detection instrument, and the dust source uses a monodisperse or polydisperse aerosol. Polydisperse aerosols are produced by spray method (cold formation). The glue source sometimes uses DOP particles, compared with the heat-generating DOP particles. Their materials are the same, but the dispersion and detection methods are not the same. 9927:1999 In the room air filter performance test method, the particle counting method is used to detect the high-efficiency filter; in Europe, the BSEN-1822 standard was established in 1998-2000, and the filter is filtered by the most transparent particle size (MPPS) method. effectiveness. The following sections will analyze and compare several standards at home and abroad from the aspects of efficiency test, leak detection and aerosol source, and focus on the problems in the process of high-efficiency filter performance testing, pointing out the future research and development direction in this field.
The pneumatic lifting table is a simplification of the automatic lifting table. It eliminates the need for a motor or compressor, and adjusts the air pressure bar manually to achieve the function of lifting
advantage:1. Low price and high cost performance 2. No need to connect to electricity, no oil, good safety.
Disadvantages:1. The stability is not high 2. It takes a little effort to raise and lower, and some buttons need to be lifted by hand to achieve the purpose of up and down.
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