Classification of explosion hazardous areas in Chi

2022-08-09
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The division of explosion hazardous areas in China is equivalent to that of the International Electrotechnical Commission in the code for electrical safety in explosion hazardous areas (Trial) jointly formulated by the former Ministry of labor and personnel, the Ministry of public security, the former machinery Commission, the former Ministry of coal, the Ministry of chemical industry, the former Ministry of petroleum, the Ministry of textiles, the Ministry of light industry and other departments, This is because it is in line with the desire of the International Electrotechnical Commission to require countries to revise regulations and unify internationally, and it is also in line with China's technical policy of approaching and being equivalent to the International Electrotechnical Commission. Gas and steam explosions are divided into zone 1, zone 2 and zone 3 in the booming border town dangerous places, mainly for the following reasons: ① it is conducive to the implementation of China's opening-up policy. From the above situation, countries are gradually approaching the IEC standard, the most authoritative standardization organization in the International Electrotechnical field, for the convenience of trade and technical exchange. After opening to the outside world, China has established trade relations with more and more countries. There is no unified standard, which will bring a lot of inconvenience to international technical exchange and cooperative design. In recent years, the petrochemical sector has introduced more and more foreign devices, while most of the major western industrial countries are based on IEC standards. The unification of the grades in the site division is not only conducive to the cooperative design and convenient for both sides of the trade, but also can obtain the same foundation and common language for the mastery of the degree of safety, which brings convenience to the spot check and acceptance work of the commodity inspection and domestic labor safety departments. ② The zoning method of the International Electrotechnical Commission is based on the release source, which is consistent with most countries. Destructive accidents such as the explosion of processing containers, large pipelines or tanks are not considered as release sources. The establishment of the concepts of continuous level, first level, second level and multi-level release sources is a step further than the simple division of industries and varieties in the past. Conversely, it can better meet the needs of various types of devices in various industries. ③ The International Electrotechnical Commission divides the area according to the frequency and duration of explosive mixture. There are two L-shaped pressing plates (a total of 8) in front of and behind the fixed beam and the moving beam (for the guidance of jaw chuck). At present, there is no special unit in China to conduct long-term measurement and statistical analysis on the annual frequency and average duration (hours) of explosive mixtures in operation units of all walks of life, so that the "maximum" figure is often not proposed in the design, but can only be determined "qualitatively". In the long run, it will lay a good foundation for how to scientifically carry out scientific experiments, statistics and prediction based on probability in the future. The feedback signal of displacement sensor should also be disconnected at this time, so that the conditions are ready to gradually move from "qualitative" to "quantitative". Some countries have proposed the following values for the probability or occurrence time of zoning boundaries, as shown in Table 1. The above figures are only for reference, but we can see the trend of countries from "qualitative" to "quantitative". ④ The division of explosion hazardous areas in China is consistent with that of the International Electrotechnical Commission, which makes the selection of explosion-proof electrical equipment more safe, economical and reasonable. For example, the places with the highest explosion hazard level are specified as level Q-1 in gbj58-83 (level B-1 in the Soviet Union), but there is no Zone 0 equivalent to the International Electrotechnical Commission. In this way, the area equivalent to zone 0 may be included in class Q-1 places. According to IEC regulations, zone 0 only allows the use of intrinsically safe "ia" electrical equipment. In Q-1, flameproof electrical equipment other than intrinsically safe type is allowed, which breeds unsafe factors. On the contrary, because the most dangerous area equivalent to zone 0 is not divided separately in class Q-1 places, it is difficult and economically unreasonable to gradually expand the scope of use of increased safety explosion-proof electrical equipment. The formulated regulations are divided into zone 0, zone 1 and zone 2. If handled properly, not only the safety is guaranteed, but also the economic benefits are great nationwide. Table 1 zoning probability country 6 zone 1 zone 2 zone dangerous zone 1. Australia 10 ~ 100% ~ < above 2. Japan 100% 10% above 3. The United States above ~ above 4. Germany has a long-term existence of more than 100 hours per year, 1 ~ 100 hours per year, and less than 1 hour per year 5. The division of Zones 0, 1, and 2 in the electrical safety code for explosive hazardous places (Trial) and Q-1 in gbj58-83 The three-level comparison relationship of Q-2 and q-3 can be shown in Table 2: Table 2 in this procedure, zone 0, zone 1, zone 2, non hazardous area gbj58-83q1, Q2, Q3, non hazardous area. From the definition of explosion hazard area classification, the clear relationship in the above table can be obtained. The above is a general introduction to the evolution of the division of explosion hazardous environment areas in foreign countries and the latest regulations of major industrial countries and China. However, in the specific use, we should combine the practical situation and use the production experience to judge, and we can't copy mechanically. According to the document of the International Electrotechnical Commission 79-10 on the classification of hazardous areas, the level of hazardous areas is related to the release source and ventilation conditions. ⑤ Area grade of dust explosion hazardous places. Places where explosive dust and combustible fibers are mixed with air to form explosive mixtures are divided into two regional levels according to the degree of danger. Grade 10 area: refers to the place where explosive dust or mixture of combustible fiber and air may occur continuously, frequently for a short time or exist for a long time under normal conditions. Grade 11 area: refers to the place where explosive dust or the mixture of combustible fiber and air cannot appear under normal conditions, and only occasionally appears for a short time under abnormal conditions

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