Experimental research on air filter efficiency

The efficiency of the air filter is different, and the detection method is also different. Therefore, when choosing an air filter, it is necessary to consider both its efficiency and its test method and test dust. my country is the first in the world to use the atmospheric dust group counting method to test the efficiency of the filter, and in 1990, it issued the 'Performance Test Method of Air Filters for General Ventilation' (GB 12218—1990) o For high-efficiency air filters, the test dust and test methods of various countries are quite different. Such as my country's 'High-efficiency air filter performance test method, transmittance and resistance' (GB/T 6165—1985) the oil mist method and the sodium flame method are used as the legal performance test method simultaneously, Germany adopts the paraffin oil mist method (DIN24185), and the UK adopts the sodium flame method (BS3928).—1969), the United States adopts DOP (dioctyl phthalate) method. Countries put forward air filter standards on the basis of selected standard test methods, such as the BS5295 standard with DOP as the test dust in the UK, EUROVENT4/9 formulated by the European Association of Air Handling Equipment Manufacturers, various air filter standards at home and abroad See Table 3-3 for comparison with efficiency. Table 3-3 Comparison of various air filter standards and efficiencies at home and abroad Chinese standard European standard EUROVENT4/9 ASHRAE standard measurement method Efficiency (%) ASHRAE standard colorimetric method Efficiency (%) American DOP method (0.3—Efficiency (%) European Standard EN 779—1993 German standard DIN24185 coarse air filter EU1<65 G1 A coarse air filter EU2 65-80 G2 B1 coarse air filter EU3 80-90 G3 B2 medium efficiency air filter EU4>90 G4 B2 medium-efficiency air filter EU5 40-60 F5 C1 medium-efficiency air filter EU6 60-80 20-25 F6 C1/C2rt high-efficiency air filter EU7 80-90 55-60 F7 C2 Chinese standard European business standard EUROVENT4 /9 ASHRAE Standard Metrology Efficiency (%) ASHRAE Standard Colorimetric Efficiency (%) American DOP Method (0.3nm) Efficiency (%) European Standard EN 779—1993 German standard DIN24185 high-efficiency air filter EU8 90-59 65-70 F8 C3 high-efficiency air filter EU9 3=95 75-80 F9 sub-high-efficiency air filter EU10>85 H10 Q sub-high efficiency air filter EU11>98 H11 R HEPA filter k EU12>99.9 H12 R/S HEPA filter A EU13>99.97 H13 S HEPA filter B EU14>99.997 H14 S/T HEPA Filter C EU15>99.997 U15 T HEPA filter D EU16>99.99997 U16 C HEPA filter D EU17>99.999997 U17 V The commonly used test methods for air filters at home and abroad are: (1) The mass method is used to test the efficiency of coarse and medium-efficiency air filters. Test principle: The filter is installed in the standard test wind tunnel, and the upper wind side continuously emits dust. The quality of the dust passing through the filter is measured at regular intervals to obtain the filtration efficiency of the filter in the calculation of the dust quality at this stage. The relevant standards for adopting this method are China's 'General Ventilation Air Filter Performance Test Method' (GB 12218—1990), American ANSI/ASHRAE52.1—1992 and European EN779—1993. (2) The colorimetric method is used for the efficiency detection of medium-efficiency air filters. Test principle: Sampling before and after the filter, the dust-laden air passes through the filter paper, and the contaminated filter paper is irradiated under the light source, and then the light transmittance of the filter paper before and after the filter is measured with a photocell colorimeter (photoelectric densitometer). Under the conditions of the same composition, size and distribution, the filtration efficiency is calculated by using the relationship between the optical density and the amount of dust accumulation. (3) The particle counter method is used for the detection and test of high-efficiency air filters in clean rooms, and is widely used in clean air-conditioning projects. Test principle: When the dust-laden airflow passes through the strong light illumination area at a small flow rate, when the dust particles in the measured air pass through in turn, each dust particle will produce a light scattering to form a light pulse signal, according to the amplitude of the light pulse signal. The size of the particle is proportional to the size of the particle surface. The number and brightness of the particles are measured by the photomultiplier tube to determine the filtration efficiency. For coarse-efficiency air filters, it can be judged according to the filtration efficiency of particle size files of ^5/zm; for general medium-efficiency air filters, the filtration efficiency of available particle-size files can be judged; for high-efficiency air filters The filtration efficiency of the particle size files that can be used by the filter judges its performance; as for the filtration efficiency of the particle size files that can be used by the sub-high-efficiency and high-efficiency air filters, the performance is judged. (4) DOP (dioctyl phthalate) method is used for the efficiency detection of high efficiency air filter. Test principle: The test dust source is 0.3/im monodisperse phase DOP droplets are heated into steam, condensed into tiny droplets under specific conditions, and the particles of about 0.3/mi are left after removing too large and too small droplets. Then, the turbidity of the gas samples before and after the filter is measured, and the filtration efficiency of the filter for 0.3/xm dust is judged. The DOP method has a history of more than 50 years, and this method used to be the most commonly used method for measuring high-efficiency air filters in the world.

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