Explosion-proof equipment standards

Explosion-proof equipment standards 27.12.2017

Explosion-proof equipment standards

ATEX - the new European standard explosion protected equipment

Explosion-proof equipment standards

Standard ATEX (Atmospheres Explosibles) explosive mixtures of gases were introduced 01.08.2003 in accordance with the requirements of the European Union 94/9/EC, which replaced the old CENELEC and used in Europe. Applies to electrical and mechanical equipment, as well as protective equipment for use in hazardous areas like underground and on the surface.

The ATEX standard has more stricter requirements:

-limit the capacitive circuit parameters;

-the use of other protection classes;

-new requirements for the electrostatics;

-use protective leather case;

Example of marking according to ATEX: II 2 G EEx ib IIB T4

Ex – marking of explosion-proof equipment

Equipment group: I – mining II – (not mine) khimindustriya, etc.

0 – with the frequent appearance of explosive gases, vapors, and mixtures;

1 – similar to 0, but the appearance of explosive gases, mixtures of vapors appears from time to time (for example, accident);

2 – similar to 1, but in rare cases the occurrence of similar situations;

G for gas, D for combustible dust, mist, fibres;

European marking of explosion-proof equipment

The scope of the equipment

Marking of explosion protection equipment









Explosion-proof equipment standards   








1. The equipment has certificates from testing laboratories of the EU;

2. Applications: I – underground application, II – ground application;

3. Category zones: 0 – permanent presence of explosive substances (more than 1000 hours per year);

4. Surrounding atmosphere: G – gas, D – dust;

5. E – according to the European standards (CENELEC); Ex – pravozashhitnoe equipment;

6. Classification types of protection:

d – flameproof enclosure;

e – increased protection;

about oil filling;

p – filling or purging shell under Risb;

q – quartz filling;

m – filling compound;

i – intrinsically safe circuit: a guarantee that an emergency will not arise as a result of a spark (short circuit) or open when the power supply circuit, or by heating the wires;

ia – a guarantee that a dangerous situation will not occur in normal operation, the interference noise on the line and when any of combinations of two faults specified in "i";

ib – a guarantee that a dangerous situation will not occur in normal operation, the interference noise on the line and when one of the malfunctions;

Also might be an additional security, after the main

7. Applications: I – underground application, II – aerial application;

When using equipment in the overhead areas for types of protection "d" and "i" are introduced subgroups IIA, IIB and IIC (according to the value of BEP or MTV)

8. Ignition temperature:

T1 > 450℃;

T2 = 300-350℃;

T3 = 200-300℃;

T4= 135-200℃;

T5= 100-135℃;

T6 = 85-100℃;

The presence of brackets in the marking indicates that the equipment associated with, for example, [Ex ia] IIC – related equipment in a hazardous area.

Classification of hazardous areas

Class hazardous area selected by qualified staff – specialists of operating organizations together with technologists. Depending on the class, the selection of the electrical equipment.

Normative documents of the Russian Federation there are the following classes of explosive zones :

1) Zone class b-1 zone located in areas where the amount of emitted hazardous gases and vapors in quantities that may form with air an explosive mixture ;

2) classes In Zone-1A zone that are located in areas where any faults, violations and accidents formed an explosive mixture of gases and vapors;

3) Zone class b-1B is different from zone 1A to the fact that explosive gases have high lower flammable limit <15%, as well as, a pungent odor at high concentrations. These include areas in laboratories and other facilities, which are gases in small quantities insufficient to produce explosive mixtures , where the work is carried out without the use of an open flame. Also, zones are not considered explosive, if all the operational work is carried out under local exhaust devices, and fume hoods;

4) Zone class b-1G – zone, which include region exterior processing units, open neftedobycha, overhead and underground tanks with flammable liquids, etc. containing flammable gases or flammable liquids;

5) Zone class b-2 zone, located in spaces in which there are combustible dusts and fibres, in such quantities that can create explosive mixtures with air;

6) Zone class b-2A zone, in which during the normal operation, life-threatening conditions do not occur;

Regulations include the determination of the geometric dimensions for each class of zones

Explosion-proof equipment standards


Zone 0

Zone 1

Zone 2

GOSTREM 51330.9-99, RUSSIA

Zone 0

Zone 1

Zone 2

PUE (2001), RUSSIA


B-Ia, B-IB, B-G

Equipment designed to operate in the zones must have the required level of explosion protection.

The level of explosion protection equipment

1) Level 2 – equipment, enhanced explosion protection, where protection is ensured only in normal operation mode;

2) Level 1 – equipment in which protection against explosions is provided not only during normal operation, but damage caused by operating conditions other than damage themselves means providing explosion protection;

3) Level 0 – equipment, in which the applied special measures of protection from explosion. Explosion-proof equipment;

The degree of explosion protection (2, 1, and 0) is placed in Russia as the first digit before the European explosion protection marking of devices.

Methods of ensuring explosion safety of equipment

The purpose of the methods of ensuring explosion safety – prevention of contact incoroorated and for heat-segregation elements of the apparatus with the external explosive environment or an obstacle outside of the explosion, by its localization.

There are several methods of ensuring explosion safety of equipment:

1) Insulation (seal) fill with compound, Polish, maintain high pressure inside the shell is achieved by purging the device with inert gas or compressed air;

2) Localization of the explosion – preventing the release of an explosion outside shell of the equipment;

3) Prevention or restriction of thermal and electric emitted energy;

4) Immersing the equipment in oil, filling sand;

European detailing applied type of explosion protection in equipment:

The type of protection

Schematic diagram

The main application


Protection of the e


Explosion-proof equipment standards   

Terminal and junction boxes, luminaires, control stations, switchgear

GOST R 51330.8-99

Explosion proof enclosure


Explosion-proof equipment standards   

Switching devices, lamps, control stations, switchgear, motor starters, heating elements

GOST R 51330.1-99

Filling or purging


Explosion-proof equipment standards   

High-current switch panels, analyzer instruments, engines

GOST R 51330.3-99

Intrinsically safe electrical circuit


Explosion-proof equipment standards   

Measuring and regulating techniques, Stasi, sensors, actuators

S GOST 51330.10-99

Oil filling of shell


Explosion-proof equipment standards   

Transformers, inrush resistance

S GOST 51330.7-99

Quartz filling the shell


Explosion-proof equipment standards   

Transformers, capacitors

GOST R 51330.6-99

Sealing compound


Explosion-proof equipment standards   

The switching devices are low power, indicators, sensors

GOST R 51330.17-99

The absence of sparking


Zone 2
This type of protection includes simplified versions of the various methods of explosion protection

All devices for the zone 2, except the switching devices

GOST R 51330.17-99

Special protection


This type of protection includes special methods of protection

Sensors, surge arresters

GOST R 51330.17-99

Airtight insulation


GOST R 51330.17-99

Russian classification of the levels of protection equipment

The category of explosive mixture

The required level of protection

I (coal mine methane)

II (all gases)



Particularly explosion-proof






Increased reliability against explosion

European classification recognized in Russia and used equipment certificates.

The category of explosive mixture

There are two categories of the potentially explosive mixture:

Category I – establishes requirements for equipment intended for use in areas with danger of methane explosion (mine, mines);

Category II – establishes requirements for equipment intended for operation in conditions which can form an explosive gas mixture;

Also, there are three subcategories II: IIA, IIB, IIC. Each can replace the previous one. The subcategory With the highest, meets the requirements of all categories A,b,C.

Russia, Europe

Ignition energy (µj)

A typical representative of


Zone 0

Increase risk

Explosion-proof equipment standards   

Methane (mining)


More than 180






less than 60

Acetylene, Hydrogen

Category of explosive mixture is isolated in the temperature-dependent self-ignition

Group mixture

The auto-ignition temperature, °C


More than 450


From 300 to 450


From 200 to 300


From 135 to 200


From 100 to 135


From 85 to 100

General requirements for equipment categories explosive gas mixtures and the ignition temperature of gas mixtures;

T1 – hydrogen, water gas, coal gas, hydrogen, 75% + nitrogen 25%

T2 – acetylene, methyldichlorosilane;

T3 – trichlorosilane;

T4 is not applied;

T5 – disulfide;

T6 – does not apply;

Categories A and b correspond to the following explosive mixtures


T1 – ammonia, acetone, benzene, 1,2-dichloroethane dichloropropane, diethylether, blast furnace gas, isobutane, methane (industrial, containing the amount of hydrogen in 75 times superior to mine methane), propane, solvents, solvent oil, alcohol datetoday, chlorobenzene, ethane;

T2 – alkylbenzene amylacetate, gasoline Б95\130, butane, solvents, alcohols, ethylbenzene, cyclohexanol;

T3 – gasoline A-66, A-72, A-76, the "boot", B-70, extraction. Butylmethacrylate, hexane, heptane, kerosene, oil, petroleum ether, polyester, pentane, turpentine, alcohols, fuel T-1 t TC – 1, white spirit, cyclohexane, ethyl mercaptan;

T4 – acetaldehyde, isobutyric aldehyde, butyric aldehyde, propionic aldehyde, Dean, tetramethylguanidine, 1,1,3 – triethoxysilane;

T5 and T6 – are not applied;


T1 – coke oven gas, hydrogen cyanide;

T2 – butadiene, 4,4 – dimethyldioxane, dimethyldichlorosilane, dioxane, nitrocyclohexane, propylene oxide, ethylene oxide, ethylene;

T3 – acrolein, vinyltrichlorosilane, hydrogen sulfide, tetrahydrofuran, tetraethoxysilane, triethoxysilane, diesel fuel, formalistically, ethyldichlorosilane, etiltsellozolv;

T4 – dietilovyi ether, diethyl ether, diethyl ether of ethylene glycol;

T5 and T6 – are not applied;

Category IIC – excessive for most applications of communication equipment.

Sub-category IIA, IIB, IIC have the following options: BEP – the maximum clearance between the flanges of the shell, through which passes the blast from the shell of the equipment to the external environment. MTV – the ratio of minimum ignition current of a mixture of explosive gas and the minimum ignition current of methane.

Category of explosive mixture

BEMZ (mm)


I (coal mine methane)

more than 1.0



0,9 and more



from 0.5 to 0.9

from 0.4 to 0.8


0.5 and less

less than 0.45

Temperature class

The temperature class of the equipment depends on the temperature, which can withstand the equipment surface during operation. Is set depending on the minimum temperature, the corresponding temperature range (its left boundary): equipment that can be used in the environment of gases and vapours with ignition temperature class T4, should have a maximum temperature of the surface elements is below 135 degrees, T5 – below 100, T6 – below 85.

Example of an application ExdIIBT4:

Ex – sign of explosion proof equipment according to the standard CENELIC;

d – type of protection ;

IIB is the category of the potentially explosive gas mixture II ;

T4 – group of the mixture at the ignition temperature (the temperature above 135 degrees Celsius);

Designation of explosion protection according to American standard FM

American standard FM (Factory Mutual) differs from the European standard form of writing. The standard also specifies the conditions of use of the device: class of explosion hazard (Class), operating conditions (Division) and group mixes, depending on their temperature of ignition (Group)

Class ( I, II, III): Class I – explosive mixtures of gases and vapors Class II – combustible dust, Class III – combustible fibers.

Division (1, 2) : Division 1 – similar to zone B1(B2) under normal working conditions there are explosive mixtures of gases and vapors. To work in this area, it is necessary to use explosion-proof equipment Division 2 – analog zone B1A (B2A) where an explosive mixture is a result of violations of technological process and accidents. In this area you must use a class a non-incendive.

There are 7 subgroups formed vapors, gases and mixtures:

Group A – mixture which contains acetylene (IIC T3, T2);

Group B – mixture containing: butadiene, acrolein, hydrogen and ethylene oxide (IIC T2, T1);

Group C – mixture containing: cyclopropane, ethylene or ethyl ether (IIB T4, T3, T2);

Group D – mix, which contain: alcohol, ammonia, benzene, butane, gasoline, hexane, lacquer, solvent vapors, naphtha, natural gas or propane (IIA T1, T2, T3, T4);

E Group – includes air concentrations of combustible metal dust

Group F – mixture containing combustible dust soot, charcoal or coke, with a white head of foam with conductivity from 100 to 100,000 Ohm-cm or flammable substances more than 8% of the volume;

Group G – suspension of combustible dust with the resistance of over 100,000 ohms-cm;

Electric accumulators in the presence of FM certification, can be used in:

Division 1: Classes I, II, III; Groups D, F, G (Intrinsically safe);

Division 2: Class I; Groups A,B ,C ,D (Non-Incendive);

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