Section 7. Electrical equipment of special installations

Electrical installations in hazardous areas. Classification of explosive mixtures according to GOST 12.1.011-78

Encyclopedia of radio electronics and electrical engineering / Rules for the installation of electrical installations (PUE)

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7.3.26. Explosive mixtures of gases and vapors with air, depending on the size of the BEMZ, are divided into categories according to Table. 7.3.1.

7.3.27. Explosive mixtures of gases and vapors with air, depending on the temperature of self-ignition, are divided into six groups according to Table. 7.3.2.

7.3.28. The distribution of explosive mixtures of gases and vapors with air by categories and groups is given in Table. 7.3.3.

Table 7.3.1. Categories of explosive mixtures of gases and vapors with air *

* The BEMZ values ​​given in the table cannot be used to control the shell gap width in operation.

Table 7.3.2. Groups of explosive mixtures of gases and vapors with air by auto-ignition temperature

Table 7.3.3. Distribution of explosive mixtures by categories and groups

* Mine methane should be understood as mine gas, in which, in addition to methane, the content of gaseous hydrocarbons - homologues of C2-C5 methane - is no more than 0,1 volume fraction, and hydrogen in gas samples from boreholes immediately after drilling is no more than 0,002 volume fraction of the total volume of combustible gases .

** In industrial methane, the hydrogen content can be up to 0,15 volume fraction.

7.3.29. The lower concentration limit of ignition of some explosive dusts, as well as their smoldering, ignition and self-ignition temperatures are given in Table. 7.3.4.

7.3.30. Categories and groups of explosive mixtures of gases and vapors with air, as well as smoldering, ignition and self-ignition temperatures of dust not included in the table. 7.3.3 and 7.3.4 are determined by testing organizations in accordance with their list in accordance with GOST 12.2.021-76.

Table 7.3.4. The lower concentration limit of ignition, the temperature of smoldering, ignition and self-ignition of explosive dusts

* Self-ignition temperature of the molten substance.

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