Classification of hazardous areas. Hazardous area classification What does ex mean

Approximate decoding of explosion-proof marking of explosion-proof rope hoist.

Hazardous area classification

The class of the explosive zone, in accordance with which the choice of electrical equipment is made, is determined by the technologists together with the specialists of the design or operating organization.

According to Russian regulatory documents, the following are distinguished hazardous area classes:

Zones of class B-1 - located in rooms in which flammable gases or vapors of flammable liquids are emitted in such an amount and with such properties that they can form explosive mixtures with air during normal operation;

Zones of class B-1a - are located in rooms in which explosive mixtures of flammable gases (regardless of the lower concentration limit of ignition) or flammable liquid vapors with air are not formed during normal operation, but only as a result of accidents or malfunctions;

Zones of class B-1b are similar to B-1a, but differ from them in that in case of accidents, flammable gases have a high lower ignition limit (15% and higher), as well as a pungent odor at hazardous concentrations. This class includes areas of laboratory and other premises in which flammable gases and flammable liquids are present in small concentrations insufficient to create an explosive mixture and where work is carried out without the use of an open flame. Zones are not classified as explosive if work with hazardous substances is carried out in hoods or under hoods;

Zones of class B-1g - spaces near external installations: technological installations containing flammable gases or flammable liquids, open oil traps, aboveground and underground tanks with flammable liquids or flammable gases (gas tanks), racks for unloading and loading flammable liquids, settling ponds with a floating oil film etc.

Zones of class B-2 - are located in rooms where flammable dust or fibers passing into a suspended state are emitted in such an amount and with such properties that they can create explosive mixtures with air during normal operation;

Zones of class B-2a are those where dangerous conditions do not arise during normal operation, but can arise as a result of accidents or malfunctions.

Normative documents contain the definition of the geometric dimensions of each class of zones.

Equipment designed to operate within a zone of a particular class must have an appropriate explosion-proof level.

Explosion protection level of equipment

The explosion protection levels of electrical equipment are designated 2, 1 and 0 in the Russian classification:

Level 2 - electrical equipment of increased reliability against explosion: in it, explosion protection is provided only in normal operation;

Level 1 - explosion-proof electrical equipment: explosion-proofness is ensured both under normal operating conditions and in case of probable damage depending on operating conditions, except for damage to the means ensuring explosion-proofness;

Level 0 - especially explosion-proof equipment, in which special measures and means of protection against explosion are applied.

The degree of explosion-proofness of the equipment (2, 1, or 0) is put in the Russian Federation as the first digit before the European marking of the explosion-proofness of the equipment.

Methods for ensuring explosion safety of equipment

There are several methods of ensuring explosion safety, the purpose of which is to prevent the possibility of contact of the internal spark-generating or heat-generating elements of the equipment with an external explosive atmosphere, or to prevent an explosion that has arisen inside the outer shell of the equipment from escaping to the outside by its localization:

Localization, or containment of an explosion - preventing the spread of an explosion outside the envelope;

Insulation, or sealing - filling with compound, varnish, maintaining high pressure inside the shell by blowing the equipment with compressed air or inert gas;

Filling the shell with quartz sand, immersing the equipment in oil, for example, for transformer windings;

Prevention, or limitation of electrical and thermal energy released - the use of "intrinsically safe electrical circuit" in the method of protection.

The European classification provides details of the type of explosion protection used in equipment (it is recognized in the Russian Federation and is found in certificates for explosion-proof equipment):

Explosion protection type		Schematic representation	Main application	Standard
Protection type e	e		Terminal and junction boxes, lamps, control stations, switchgear	GOST R 51330.8-99
Explosion-proof enclosure	d		Switching devices, lamps, control stations, switchgears, motor starters, heating elements	GOST R 51330.1-99
Filling or purging	p		High-current electrical cabinets, analyzers, motors	GOST R 51330.3-99
Intrinsically safe electrical circuit	i		Measuring and control technology, communication technology, sensors, drives	GOST Z 51330.10-99
Oil-filled shell	o		Transformers, starting resistors	GOST Z 51330.7-99
Quartz filling of the shell	q		Transformers, capacitors	GOST R 51330.6-99
Compound sealing	m		Low power switching devices, indicators, sensors	GOST R 51330.17-99
No sparking	n	Zone 2 This type of protection includes simplified versions of the various methods of protection	All devices for zone 2, except switching devices	GOST R 51330.17-99
Special protection	s	This type of protection includes special methods of protection	Sensors, arresters	GOST R 51330.17-99
Hermetic insulation	h			GOST R 51330.17-99

The following Russian classification of equipment explosion protection levels is in effect:

The existing classification provides for two categories: I and II:

There are three subcategories of category II: IIA, IIB, IIC. Each subsequent subcategory includes (can replace) the previous one, that is, subcategory C is the highest and meets the requirements of all categories - A, B and C. It, therefore, is the most "strict".

According to GOST, the following classification by autoignition temperature is valid:

T1 - hydrogen, water gas, luminous gas, hydrogen 75% + nitrogen 25% ";

T2 - acetylene, methyldichlorosilane;

T3 - trichlorosilane;

T4 - not applicable;

T5 - carbon disulfide;

T6 - not applicable.

T1 - ammonia, ..., acetone, ..., benzene, 1,2-dichloropropane, dichloroethane, diethylamine, ..., blast furnace gas, isobutane, ..., methane (industrial, with a hydrogen content 75 times higher than in mine methane), propane ,…, Solvents, petroleum solvent, diacetone alcohol,…, chlorobenzene,…, ethane;

T2 - alkylbenzene, amyl acetate, ..., gasoline B95 \ 130, butane, ... solvents ..., alcohols, ..., ethylbenzene, cyclohexanol;

T3 - gasolines A-66, A-72, A-76, galosha, B-70, extraction. Butyl methacrylate, hexane, heptane, ..., kerosene, oil, petroleum ether, polyester, pentane, turpentine, alcohols, T-1 and TC-1 fuels, white spirit, cyclohexane, ethyl mercaptan;

T4 - acetaldehyde, isobutyric aldehyde, butyric aldehyde, propionic aldehyde, decane, tetramethyldiaminomethane, 1,1,3 - triethoxybutane;

T5 and T6 - not applicable.

T1 - coke oven gas, hydrocyanic acid;

T2 - divinyl, 4,4 - dimethyldioxane, dimethyldichlorosilane, dioxane, ..., nitrocyclohexane, propylene oxide, ethylene oxide, ..., ethylene;

T3 - acrolein, vinyltrichlorosilane, hydrogen sulfide, tetrahydrofuran, tetraethoxysilane, triethoxysilane, diesel fuel, formalglycol, ethyldichlorosilane, ethyl cellosolve;

T4 - dibutyl ether, diethyl ether, ethylene glycol diethyl ether;

T5 and T6 - not applicable.

Additional Information.

Categories IIA, IIB and IIC are determined by the following parameters: safe experimental maximum clearance (BEMZ is the maximum clearance between the shell flanges through which no explosion is transmitted from the shell to the environment) and the MTB value (the ratio of the minimum ignition current of an explosive gas mixture and the minimum ignition current methane).

Temperature class

The temperature class of electrical equipment is determined by the limiting temperature in degrees Celsius that the surface of explosion-proof equipment can have during operation.

The temperature class of the equipment is set based on the minimum temperature of the corresponding temperature range (its left border): equipment that can be used in an environment of gases with a self-ignition temperature of class T4 must have a maximum temperature of surface elements below 135 degrees; T5 is below 100 and T6 is below 85.

Consider an example of labeling (used in Europe before July 1, 2003) according to the “CENELEC” standard:
ExdIIBT4

Ex- sign of explosion-proof equipment according to CENELEC standard;
d- type of explosion protection (flameproof enclosure);
IIB- explosion hazard category of the gas mixture II, option B (see above);
T4- mixture group by ignition temperature (temperature not higher than 135 Сº); 

FM Explosion Proof Symbols

Factory Mutual (FM) are essentially identical to European and Russian standards, but differ from them in the form of recording. The American standard also specifies the conditions for the use of the equipment: the explosion hazard class of the environment (Class), the operating conditions (Division) and the group of the mixture according to their auto-ignition temperature (Group).

Class can be I, II, III: Class I - explosive mixtures of gases and vapors, Class II - combustible dust, Class III - combustible fibers.

Division can have values ​​1 and 2: Division 1 is a complete analogue of zone B1 (B2) - an explosive mixture is present under normal operating conditions; Division 2 is an analogue of zone В1А (В2А), in which an explosive mixture can appear only as a result of an accident or disturbances in the technological process.

To work in zone Div.1 requires especially explosion-proof equipment (in terms of the standard - intrinsically safe), and for work in zone Div.2 - explosion-proof equipment of the Non-Incendive class.

Explosive air mixtures, gases, vapors form 7 subgroups, which have direct analogies in Russian and European standards:

Group A - mixtures containing acetylene (IIC T3, T2);

Group B - mixtures containing butadiene, acrolein, hydrogen and ethylene oxide (IIС T2, T1);

Group C - mixtures containing cyclopropane, ethylene or ethyl ether (IIB T4, T3, T2);

Group D - mixtures containing alcohols, ammonia, benzene, butane, gasoline, hexane, varnishes, solvent vapors, kerosene, natural gas or propane (IIA T1, T2, T3, T4);

Group E - air suspension of combustible metal dust particles, regardless of its electrical conductivity, or dust with similar hazard characteristics, having a specific volumetric conductivity of less than 100 KΩ - see.

Group F - mixtures containing combustible dust of soot, charcoal or coke with a combustible substance content of more than 8% by volume, or suspensions having a conductivity of 100 to 100,000 ohm-cm;

Group G - suspensions of combustible dust with a resistance of more than 100,000 ohm-cm.

FM approved electric batteries can be used in the following cases:

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

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

ATEX - the new European standard for explosion-proof equipment

In accordance with the EU directive 94/9 / EC, from July 1, 2003, a new ATEX standard is introduced. The new classification will replace the old CENELEC and will be introduced in European countries.

ATEX Is an abbreviation for ATmospheres Explosibles. ATEX requirements apply to mechanical, electrical equipment and protective equipment that are intended to be used in a potentially explosive atmosphere, both underground and on the surface of the earth.

The ATEX standard toughens the requirements of the EN50020 / EN50014 standards in terms of IS (Intrinsically Safe) equipment. These toughenings include:

Limiting the capacitive parameters of the circuit;

Use of other protection classes;

New requirements for electrostatics;

Using a protective leather case.

Let us consider the ATEX classification marking of explosion-proof equipment using the following example: II 2 G EEx ib IIB T4

Ex in hex - marking of explosion-proof equipment according to ATEX.

The following labeling element identifies the equipment group:

I - mine;

II - other (not mine): chemical industry, petrochemical plant, oil refinery, etc. The third element - an Arabic numeral - determines the permissible operating area of ​​the equipment, it can take the values ​​0, 1 or 2:

0 - with frequent occurrence of explosive or flammable concentrations of hazardous gases or mixtures (gases, suspensions);

1 - the same as 0, but the indicated concentrations can occur only from time to time (for example, in emergency situations);

2 - the same as 1, but in rare cases of these situations.

The fourth element: G - for gases, D - for combustible dusts, fibers and suspensions.

Further symbols (after E Ex) were discussed earlier.

European marking for explosion-proof equipment

1. Explosion-proof equipment has certificates of one of the testing laboratories of the EU countries.

2. Scope:

I - underground workings;

II - ground use.

0 - constant presence of explosive substances (more than 1000 hours per year);

1 - frequent 10 ... 1000 hours per year;

2 - short-term less than 10 hours per year.

4. Ambient atmosphere:

D is dust.

5. Е - according to European standards (CENELEC requirements); Ex - explosion-proof equipment.

6. Classification of types of protection:

D - flameproof enclosure;

E - protection type "e" (increased);

О - oil filling;

Р - filling or purging the shell under Rizb;

Q - quartz filling;

M - filling with compound;

I - intrinsically safe electrical circuit: (this type of explosion protection guarantees that a dangerous situation cannot arise as a result of a spark (in case of a short circuit), or in the event of a sudden break in the power supply circuit (energy of the internal inductance of the device), or as a result of heating of current-carrying wires);

Ia - a dangerous situation cannot arise during normal operation with interference on the line and with any combination of two possible malfunctions;

Ib - a dangerous situation cannot occur during normal operation, with line noise and one fault.

After the main type of protection, an additional one may be indicated.

7. Scope of application:

I - underground work;

II - ground use;

For types of protection "D" and "I" in the case of ground use, subgroups are introduced IIA, IIB and IIC(according to the size of BEMZ or MTV).

8. Ignition temperature:

T1> 450 ° C;

T2 = 300 ... 450 ° С;

T3 = 200 ... 300 ° C;

T4 = 135 ... 200 ° C;

T5 = 100 ... 135 ° C;

T6 = 85 ... 100 ° C.

Markings in square brackets indicate that it is related equipment.
For example, the IIC mark indicates associated equipment located in a hazardous area.
Associated equipment located in a hazardous area and having the type of protection "flameproof enclosure" is marked as follows: Ex d IICT4.

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The word "ex" has many meanings. It can be a prefix, an abbreviation, or an abbreviation. Read about what "ex" is in our article. And you can find out about other words on our website in the section.

"Ex-" as a prefix

The most common meaning of the prefix "ex-" is "former" or "past". In this version, it is written with a hyphen: for example, "ex-director" ("former director"), "ex-owner" ("former owner"), "ex-president" ("former president").

In addition, the prefix "ex-" can be part of foreign words, denoting an exit, movement outward. For example, "exhumation" is the removal of a burial from the ground, "expatriation" is the expulsion of a person from the country.

"Ex" as an abbreviation

Understanding what "ex" means as an independent word is quite simple if you know the meaning of the prefix. Very often "ex" in colloquial speech is used as an abbreviation - for example, from "ex-boyfriend". There is also a specific meaning: Russian revolutionaries at the beginning of the 20th century called expropriation - a robbery in order to finance revolutionary activities - as "exs".

"EKS" as an abbreviation

In addition to the prefix and abbreviation, "EKS" can also be used as an abbreviation. Most often, this is understood as a pacemaker. A more narrowly specialized meaning is an emergency caesarean section.