(1) sodium flame method
Sodium flame in 1969 originated in the United Kingdom, some European countries in the 20th century, 70 to 90 years to implement, is one of China’s current national standard method. Its test dust source for the multi-dispersed phase sodium chloride salt spray, “quantity” for the combustion of salt spray with hydrogen flame brightness. Brine in the compressed air under the agitation splash, the formation of small particles of salt crystals and drying into the air duct, respectively, before and after the filter in the sample, salt mist gas to hydrogen flame color blue, brightness increases, the flame brightness to determine the air Of the salt spray concentration, and to determine the filter on the salt spray filtration efficiency, the main detection instrument for the flame photometer. Sodium flame law related standards are: the United Kingdom BS3928-1969, Europe Eurovent4 / 4, China GB6165-85. The method can only detect the sensitivity is not high, can not be ultra-efficient filter detection.
(2) oil mist method
Oil mist method originated in Germany, China and the former Soviet Union also implemented. Test the dust source for the oil mist, “quantity” for the oil mist air turbidity, before and after the gas filter to determine the difference between the turbidity of the filter oil mist filter efficiency. Germany requires the use of paraffin oil, oil mist particle size of 0.3 ~ 0.5 & m; The Chinese standard stipulates that the average weight diameter of oil mist is 0.28 ~ 0.34 um, the type of oil is not specified. The relevant standards are: China GB6165-85, Germany DIN24184-1990. Oil mist method in the detection of filters, easy to damage the filter, and can not read the value directly, a waste of time. German oil mist law has become history, Germany in 1993, the first to promulgate the count method for the detection of national standards, the European standard EN-1822 is based on the German standard developed. China only a few military units to use the method.
(3) DOP method
DOP method originated in the United States in 1956, has been adopted by many countries, China’s national standard has also been adopted, this method was the most commonly used method of testing efficient filters. Its test dust source is 0.3 μm micro dispersed mono-phthalate (DOP) droplets, also known as “hot DOP”, “amount” is DOP-containing air turbidity. DOP liquid is heated to steam, steam under certain conditions, condenses into tiny droplets, remove too large and too small droplets left behind 0.3? M particles, into the duct, by measuring the gas before and after the filter Turbidity, and thus determine the filter on the 0.3 μ m dust filtration efficiency. The measuring instrument is mainly a light scattering photometer. The relevant standards are: MIL-STD-282-1956.
(4) fluorescence method
Fluorescence method is only used in France, the fluorescence source of the test method for the generation of sodium fluorescein dust spray. Test method is first in the filter before and after sampling, and then dissolved in water on the filter paper sodium fluorescein, and then measured with sodium fluorescein aqueous solution under certain conditions of fluorescence brightness, brightness reaction dust weight, which calculated the filter filter effectiveness. France has long been no fluorescence method, they will also be the European Standardization Association of the statute law for the national standard, a number of nuclear industry system on-site detection of the filter also uses fluorescence method.
(5) particle counting method
The method is common in Europe, the United States ultra-efficient filter test methods are relatively similar, is the international mainstream test methods. Dust sources are polydisperse droplets, or solid dusts of defined particle size. In some cases, the filter manufacturer should use atmospheric dust or other specific dust as specified by the user. If a coagulation core counter is used, a monodisperse phase test dust source with a known particle size must be used. The main measuring instrument is a large flow laser particle counter or condensation nucleus counter (CNC). With the counter to filter the entire wind surface scan test, the counter gives the number of dust per point, you can also compare the local efficiency of each point.
