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Explosion-proof area division
Dec 13, 2022|
View:2731.Hazardous location zoning
The meaning of hazardous location area is a measure of the actual possibility of danger in the area, thereby specifying the applicable explosion-proof type. The explosion-proof areas classified by the International Electrotechnical Commission/European Electrotechnical Commission are:
Zone 0: An area where there is a continuous hazard greater than 1000 hours/year
Zone 1: An area where there is a hazard intermittently for 10 to 1000 hours/year
Zone 2: The area where the danger exists in an accident state for 1 to 10 hours/year
2. Analysis of explosion-proof signs
①Gas group
| Typical Hazardous Gases | European Committee for Electrotechnical Standardization | North American NEC500 terms | China | Minimum ignition energy |
| EN50014EC | CLASS1 air | GB-3836-1 | (microfocus) | |
| Acetylene | ⅡC | A | ⅡC | 20 |
| hydrogen | ⅡC | A | ⅡC | 20 |
| Vinyl | ⅡB | C | ⅡB | 60 |
| Propane | ⅡA | D | ⅡA | 180 |
Note:
The Chinese GB3836 standard stipulates that the minimum ignition energy of Class IIC is 19 microjoules, and the minimum ignition energy of Class IIA is 200 microjoules.
Gas grouping and ignition temperature are related to the mixed concentration of flammable gas and air at a certain ambient temperature and pressure.
② Temperature group (T group)
| Maximum surface temperature (°C) | Temperature group | |
| IEC79-8 | GB3836-1 | |
| 450°C | T1 | T1 |
| 300°C | T2 | T2 |
| 200°C | T3 | T3 |
| 135°C | T4 | T4 |
| 100°C | T5 | T5 |
| 85°C | T6 | T6 |
This is the highest surface temperature of electrical equipment (assuming an ambient temperature of 40C) related to the ignition temperature of the gas, and the ignition energy has nothing to do with the ignition temperature. All flammable gases and their groups are listed in the standard BS5345 Part 1.
| class and level | MESG/mm | MICR | Temperature grade and group/°C | |||||
| T1 | T2 | T3 | T4 | T5 | T6 | |||
| Ⅰ | MESG= 1.14 | 1 | Methane | |||||
| ⅡA | 0.9<MESG<1.14 | 0.8<MICR<1.0 | Ethane, propane, acetone, styrene, vinylidene chloride, benzene, benzene, ammonia, methanol, carbon monoxide, methyl acetate, acetic acid | Butane, Ethyl Butane, Acetic Acid, Propyl Acetate, Acetic Acid | Pentane, hexane, heptane, decane, kerosene, | trimethylamine, acetaldehyde | Ethyl nitrite | |
| Cyclohexane | ||||||||
| ⅡB | 0.5<MESG≤0.9 | 0.45<MICR≤0.8 | Dimethyl ether, town gas, cyclopropane | Acrylic methyl, vinyl | Dimethicone, acrylic acid | Dibutyl ether | ||
| ⅡC | MESG≤0.5 | MICR≤0.5 | Water gas, hydrogen | Acetylene | Carbon disulfide | Ethyl nitrate | ||
3. Division of common explosion-proof areas in chemical industry
In principle, the districts listed in Table 3 where explosive gases exist are all explosion-proof districts.
In general, the following situations do not belong to the explosion-proof area:
thermal power plant
Air separation plant
