1. Categories of explosive mixtures

Production processes where explosive mixtures of gases, vapours, dusts or fibres with air may occur are divided into explosive zones by classes.

Zones of Class B-I are zones where the formation of explosive mixtures of gases and vapours is possible under normal working conditions.

Zones of Class B-la are zones where the formation of explosive mixtures of gases and vapours is possible only as a result of accidents and malfunctions.

Zones of Class B-Ib are zones which differ among each other with one of the particularities:

  • Combustible gases in these areas have a high lower concentration limit of flaming (15 per cent or more) and a sharp odour at permissible concentrations (e.g. ammonia).

  • Spaces related to formation of gaseous hydrogen are not more than 5% of the free space.

Zones of Class B-lr - exterior installations spaces above and below-ground tanks with liquids or flammable gases, or spaces at openings outside the exterior fences of the spaces with the B-l, B-la, C-II class areas.

Zones of Class B-II are zones located in the spaces where the dust and fibres that rise into suspension, which are capable of forming explosive mixtures with the air under normal modes of operation, are allocated.

Zones of Class B-IIa are zones where the dangerous conditions that are of Class B-II are only possible as a result of accidents or malfunctions.

Table of approximate conformity of PEU and GOST 30852.9-2002

Zone 0, where

explosive gas mixture is present permanently or for long periods of time

Zone 1, which is likely to present an explosive gas mixture under normal operating conditions

Zone 2, where the presence of an explosive gas mixture is unlikely under normal operating conditions and, if it occurs, is rare and very short.

cenelec/iec, europe

Zone 0

Zone 1

Zone 2

gost r 30852.9-2002, russia

Zone 0

Zone 1

Zone 2

pue (2003), russia

B-l, B-ll

B-la, B-Ib, B-Ig, B-lla

2. Types of explosion protection

Type of explosion protection – special measures provided in electrical equipment to prevent the ignition of an explosive gas environment.

Type and principle of explosion protection Schematic diagram Main application
Explosion-proof enclosure.
Spread of the explosion to external environment is excluded.
Ex d VELAN erminal and junction boxes, switch appliances, lighting fixtures, control stations, distribution devices, starters, motors, heating elements, control panels, IT equipment zone 1, zone 2.
Protection of type е.
Elimination of spark or elevated temperature.
Ex e VELAN Terminal and junction boxes, lighting fixtures, control stations, distribution devices, heating elements zone 1 (partially), zone 2.
intrinsically safe electrical circuit. Ex i VELAN Measuring and regulating equipment, communications equipment, sensors, drives, and battery lights.
Level of explosion protection of Exi-equipment.
Limitation of spark energy or elevated temperature. Explosive zone 0 1 2

ia ia, ib ia, ib, ic
Filling or blowing under excessive pressure.
Ех - atmosphere is isolated from the source of ignition.
Ex p VELAN Current switchboard panels, highly integrated IT equipment, analyzer appliances, heavy-duty motors. Zone 1, Zone 2
Compound encapsulation.
Еx - atmosphere is isolated from the source of ignition.
Ex m VELAN Switching appliances of low power, indicators, sensors.
Zone 1, Zone 2
Oil immersion of enclosure.
Ех - atmosphere is isolated from the source of ignition.
Ex 0 VELAN Transformers, resistance starters.
Zone 2
Powder filling of enclosure.
Ex - atmosphere is isolated from the source of ignition.
Ex q VELAN Transformers, capacitors, indicators.
Zone 1, Zone 2
n protection type
do not have incendiary capacity.
Ex n VELAN All devices of zone 2.

Ex n equipment is divided into four groups:

  • Non sparking Ex nA - components that do not produce an arc or sparking.
  • Isolated Ex nC components with incendiary capacity, such as lamp holders, are isolated to prevent explosive gases or vapours from intrusion.
  • Energy limitations Ex nL- low energy schemes eliminate the possibility of ignition.
  • Air movement limitation Ex-nR is based on sealing equipment to eliminate intrusion of explosive mixtures on hot surfaces and inflammable components.
Special protection. Ex s This type of explosion protection includes special methods. All devices for zone 1 and zone 2.


3. Distribution of explosive mixtures of gases and vapours with air by categories and groups
Mixture category Mixture group Substances which form an explosive mixture by air intrusion
I T1 Methane (mine) *
IIa T1 Ammonia, alkyl chloride, acetone, acetonitrile, benzene, benzotriflouride, vinyl chloride, vinylidene chloride, 1.2-Dichloropropene, Dichloroethane, Diethylamine, diisopropyl ether, domain gas, isobutylene, isobutane, izopropilbenzol, acetic acid, xylene, methane (industrial) methyl acetate, α-metilstirol, bromide chloride, methyl isocyanate, methyl chloroformate, methyl cyclopropyl ketone, methyl ethylketone, carbon monoxide, propane, pyridin, solvents R-4.
R-5 and RS-1, RE-1 diluent, oil solvent, styren, diacetone alcohol, toluol, Triflourrpropan, tridifluorethane, Triftlourethylen, Triethylamine, Chlorobenzene, cyclopentadiene, Ethan, Ethyl chloride.
T2 Alkyl benzene, amyl acetate, acetic anhydride, acetylacetone, acetyl chloride, Acetopropilhlorid, Petrol b95/130, Bhutan, butyl acetate, Butilpropionat, vinyl acetate, Viniliden fluoride, Diatol, Diisopropylamine, Dimetilamin, Dimetilformamid, Isopentane, isoprene, isopropylamine, Isooctane, acid, methylamin, methyl isobutyl ketone, methyl methacrylate, methyl mercaptan, Metiltrihlorsilan, 2-Metiltiofen, Metilfuran, Monoizobutilamin, Metilfuran, Monoizobutilamin, Metilhlormetilhlorsilan, mesityl oxide, Pentadien-1.3, propilamin, propylene. Solvents: №646,647,648,649, RS-2, BEF and AZ. Diluents: RDV, RKB-1, RKB-2. Alcohols: Butyl normal, butyl tertiary, ISO-amyl, isobutyl, isopropyl, methyl, ethyl. Triffluorpropil metildichloridesilan, trifluoroethylene, Isobutyl chloride, ethylamine, Ethyl, Ethyl butyrate, Etilendiamin, ethylene chlorohydrin, ethyl butyrate, ethyl Benzene, cyclohexanol, ketohexamethylene.
T3 Petrols: А66, А72, А-76, “GALOSHA”, B-70, extracted as per TR 38.101.303-72, extracted as per MRTU12N -20-63. Butyl methacrylate, hexane, Heptane, Diizobutilamin, dipropilamin, aldehyde isovalerianic, Izoktilen, Camphene, kerosene, various boron, oil, ether ether, polyester TGM-3, pentane, solvent No. 651, turpentine, alcohol amylic, tretilamin, fuel T-1 and TC-1, White spirit, cyclohexane, cyclohexylamine, ethyldifluorphosphate, Ethylmercaptane.
T4 Acetaldehyde, aldehyde isobutyric, aldehyde oil, aldehydeing, decane, tetramethyldiaminomethane, 1, 1, 3- Powell frother.
T5
T6
IIb T1 Coke gas, prussic acid.
T2 divinyl, 4,4-dimethyldioxane, dimethylfluorsylan, dioxane, iethyldifloursyane, camphor oil, acrylic acid, methyl acrylate, methylvinyldichlorosilane, acrylonitrile, nitrocyclogexane, ethylene oxide, AMR-3 and АКN solvents, trimethylchlorosilane, formaldehyde, furfuran, furfurol, epichlorhydrin, ethyl trichlorosilane, ethylene.
T3 Acrylaldehyde, vinyltrichlorosilane, hydrogen sulphide, tetrahydrofurane, Tetraethoxysilane, diesel fuel, formalglycole, ethyldifluorsylane, ethyl cellosolve.
T4 Dibutyl ether, diethyl ether, EG diethyl ether
T5
T6
IIc T1 hydrogen, water-gas, coal-gas, hydrogen 75%+ nitrogen 25%.
T2 Acetylene, methyldichlorosilane.
T3 Trichlorosilane.
T4
T5 Carbon disulfide.
T6
4. Temperature classes

Взрывоопасные смеси газов и паров подразделяются на группы в зависимости от температуры самовоспламенения согласно таблицы:

Explosive mixtures of gases and vapours are divided into groups depending on the combustion temperature as per the table:
Main application Ignition temperature, ° C Characteristic gas, mixture Maximum permissible temperature on the surface of appliance, ° C Temperature group of the explosive mixture for which the electrical equipment is explosion-proof
T1 more than 450 ° C Acetone, hydrogen, propane 450°C T1
T2 from 300 ° C to 450 ° C Bhutan, alcohol, acetylene 300°C Т1, Т2
T3 from 200 ° C to 300 ° C Petrols, kerosene, turpentine, oil 200°C Т1, Т2, Т3
T4 from 135°C to 200°C Acetaldehyde, diethyl ether 135°C Т1, Т2, Т3, Т4
T5 from 100 ° C to 135 ° C Carbon disulfide 100°C Т1, Т2, Т3, Т4, Т5
T6 from 85 ° C to 100 ° C 85°C Т1, Т2, Т3, Т4, Т5, Т6

5. Ingress protection (IP)
For safe and secure operation of the electrical equipment, it is placed in enclosures, which protect service personnel from contact with the moving parts or parts under tension, and also prevent the electrical installation of solid extraneous bodies and water. IP is the method of protection provided by enclosure from access to dangerous parts, external solids and/or water, and tested by standard test methods. As per GOST 14254 of 01.01.1997 IP code is the codification system used to provide the degree of protection provided by enclosure from access to dangerous parts, the entry of external solids, water, and the provision of additional information related to such protection. As per GOST 14254 of 01.01.1997, IP codes characterize: Personnel protection from touching or accessing the hot or moving parts (except smooth rotating shafts, etc.) located inside enclosure; Protection of electrical equipment from the penetration of solid foreign bodies; Protection of electrical equipment from harmful intrusion of water. Ingress protection is indicated by GOST 14254 with letters IP (Index of protection) and two digits. The first digit describes the degree of protection from penetration of the solid body into enclosure, and the second is the degree of protection against water intrusion.
1st digit
Protection from solid objects and dust 2nd digit
Water protection
0
No protectionт 0
No protection
1 50mm velan Protection from solids with a diameter of more than 50 mm (protection against accidental touching of a large section of a human body with current carrying or moving parts inside enclosure of appliance) 1 velan Protection from vertically falling drops of water
2 12,5mm velan Protection from solid objects with a diameter of more than 12.5 mm (protection against possible contact of fingers with current carrying or moving parts inside enclosure of appliance) 2 velan Protection against drops of water falling on enclosure inclined at an angle of to 15 ° to the vertical
3 2,5mm velan Protection from solid objects with a diameter of more than 2.5 mm (protection against possible contact of the instrument, wire, etc. with current carrying or moving parts inside enclosure of appliance) 3 velan Protection from rain that falls on enclosure inclined at an angle of to 60 ° to the vertical
4 1mm velan Protection from solid objects in diameter of more than 1mm (protection against possible contact of fingers with current carrying or moving parts inside enclosure of appliance) 4 velan Protection from water spatters of any direction
5 velan Dust protection. Full protection of personnel from contacting current carrying or moving parts inside enclosure of appliance 5 velan Protection from water jets of any direction
6 velan Full dust protection. Full protection of personnel from contacting current carrying or moving parts inside enclosure of appliance 6 velan Protection from water waves
-

7 velan Protection when immersed in water up to 1 meter deep within 30 minutes
-

8 velan Protection for long immersion in water
6. Climatic category

Electrical equipment and items intended for use in certain climatic areas on land, rivers and lakes are released in the following climatic categories as per GOST 15150 and have letters in Russian and Latin alphabet respectively.

Climatic category of items Designation
For macroclimatic moderate area (from-45 ° C to + 40 ° C) U (N) Moderate
For moderate and cold macroclimatic area (from-60 ° C to + 40 ° C) UHL (NF) moderate and cold
For macroclimatic area with cold climate (from-60 ° C to + 40 ° C) HL (F) cold
For macroclimatic area with humid tropical climate (+ 1 ° C to + 45 ° C) TV (TH) humid tropical
For macroclimatic area with humid tropical climate (+ 1 ° C to + 45 ° C) TV (TH) humid tropical
For macroclimatic area with dry tropical climate (from-10 ° C to + 50 ° C) Т (T) dry and humid tropical
For all macroclimatic areas on land except the macroclimatic area with a very cold climate (from-60 ° C to + 50 ° C) 0 (U) general climatic category
For macroclimatic area with moderate and cold sea climate (from-40 ° C to + 40 ° C) М (M) moderate cold sea climate
For macroclimatic area with tropical sea climate, including vessels of coastal navigation or other destined for navigation only in this area (+ 1 ° C to + 45 ° C) ТМ (TM) tropical sea climate
For macroclimatic areas of moderate and tropical sea climate, includingfor vessels of unlimited navigation (from-40 ° C to + 45 ° C) ОМ (MU) moderate cold and tropical sea
Items designed for use in all climatic areas on land and at sea, except macroclimatic area with very cold climate (pan-climatic category) (from-60 ° C to + 50 ° C) V (W) pan-climatic category е

7. Placement categories of electrical equipment
Characteristic Designation
For outdoor use. 1
For operation under impounding or in a facility where the fluctuations in air temperature and humidity are not significantly different from those in the open air and there is relatively free outdoor air access. 2
For operation under impounding or in a facility where the fluctuations in air temperature and humidity are not significantly different from those in the open air and there is relatively free outdoor air access. 2
For operation in closed spaces with natural ventilation, without artificially controlled climatic conditions, where fluctuations in temperature and humidity and the impact of sand and dust are significantly lower than outdoor air. 3
For operation in premises with artificially controlled climatic conditions, such as closed heated or cooled and ventilated production and other facilities, including well ventilated underground facilities. 4
For operation in high-humidity rooms, such as in unheated and unventilated underground spaces, including mines, cellars, ships, shipments and other facilities where water is possible for a long time or where moisture is condensed on walls and ceilings. 5