Ex code indicates that the equipment has labeled protections against the explosion and then the next symbol shows the type of protection, which is achieved by means of explosion protection. According to the European classification adopted also in the Russian Federation, there are The following types of protection: d – flameproof enclosure e – Increased safety ia, ib, ic – intrinsically safe (IBTS); h – sealed insulation m – partitioning into capsules with the isolation of an explosive atmosphere o – oil filling p – method of high pressure q – powder filling s – special protection, for example, consider the type of protection Ex industrial telephone Ex ResistTel. His markings – 2Exem ib IICT5. Explosion phone have such protections as' intrinsically safe ',' increased safety 'and' partition on the capsule with the isolation of an explosive atmosphere. " The marking appropriated for communications equipment based on Certification provides information on the conditions in which the equipment will be explosion proof.
This information is contained in the code following the type of protection. The first code is a pointer category of gases and vapors, and the second shows the physical parameters determined for each gas or vapor mixtures – ignition temperature. Gas or steam mixture are classified as follows: Group I – Gas and steam mixture in mines (underground work), Group II – gas and steam mixture to all other objects and types of work group II, in turn, divided into subgroups – IIA, IIB and IIC Subgroups vary the degree of explosion, characterized by the following physical parameters – 'maximum clearance between the flanges of the shell, through which there is no transmission of the explosion from the inside of the shell to the external environment' – short BEMZ, and 'minimum current ignition mixture with respect to the current auto-ignition of methane ', for short – MTV. Explosive gas atmosphere is growing from the top down, so the equipment, found fit for use in class IIC, can be used and in the subgroups IIB and IIA. Often such equipment is marked with only the group number II.
From this classification it follows that, for example, explosion-proof telephone Ex ResistTel labeling of which contains a cipher II, may be used in all industries and jobs, except for mines or other underground works, in all gaseous environments, the respective temperature class T5. Total classification of gas ignition temperature according to Russian State Standards includes six items from T1 to T6 inclusive. Numeral before the symbol Ex labeling indicates the level of protection. There are three: Level 2 – "equipment with superior explosion" – Explosion-proof electrical equipment in MDM provides protection during normal operation, Level 1 – "Explosion-proof equipment" – explosion-proof electrical equipment in which protection is provided as a