Annex 1

to the Technical Regulation of

the Customs union «On safety of

equipment intended for use in

explosive atmospheres»

(ТР ТС 012/2011)

 

Classification of parameters defining the explosion safety of equipment

I. Classification of hazardous areas

1.   Classification of hazardous areas is used for the purpose of selection of equipment according to its level of protection providing safety operation of such equipment in the relevant hazardous zone.

2.   Hazardous areas are classified according to frequency of the occurrence and duration of an explosive gas or dust atmosphere into the following zones:

explosive gas atmospheres - zones 0, 1 and 2;

explosive dust atmospheres - zones 20, 21 and 22.

II. Equipment grouping

According to the field of application electrical equipment is divided into the following groups:

1) Group I equipment - equipment intended for use in underground mines and surface installations of such mines susceptible to firedamp and (or) combustible dust. Depending on construction to group I equipment one of three equipment protection levels can be assigned;

2) Group II equipment - equipment intended for use in places with an explosive gas atmospheres other than underground mines and surface installations of such mines. Depending on construction to group II equipment one of three equipment protection levels can be assigned. Group II equipment is subdivided into the sub-groups IIA, IIB, IIC according to the category of the explosive mixture it is intended to be used in;

3) Group III equipment – equipment intended for use in places with explosive dust atmosphere other than underground mines and surface installations of such mines. Depending on construction to group II equipment one of three equipment protection levels can be assigned. Group III equipment is subdivided into the sub-groups IIIA, IIIB, IIIC according to the category of the explosive mixture it is intended to be used in;

III. Classification of equipment according to equipment protection levels

1.   According to the likelihood of becoming a source of ignition and conditions of its use in explosive atmospheres equipment is classified to equipment protection levels:

1)   «ultra explosion-proof» («very high»);

2)   «explosion-proof» («high»);

3)   «equipment protection by increased safety» («increase safety») .

2.   Ultra explosion-proof («very high») equipment protection level is applied to equipment intended for use in accordance with the operational parameters specified by the manufacturer, ensures the required equipment protection level even in the event of rare failures relating to equipment, with an explosive atmosphere present, and which in the event of failure of one means of protection, at least an independent second means provides the required level of protection or the required level of protection is assured in the event of two failures occurring independently of each other;

Equipment with this equipment protection level is intended for use in underground mines and surface installations of such mines suseptabel to firedamp and/or combustible dust (group I equipment) or at the objects and/or its parts (group II and II equipment) where explosive atmosphere, created by the mixture with air of flammable substances in the form of gas, vapour, dust, fibres, or flyings is present permanently for long-term periods or frequently.

3. Explosion-proof («very high») equipment protection level is applied to the equipment intended for use in accordance with the operational parameters specified by the manufacturer, ensures the required equipment protection level and functioning under normal operation mode in the event of single recognized expected fault.

Group I equipment with this equipment protection level shall be provided with the means of safe shutdown when the specified concentration of the firedamp in the surrounding atmosphere achieves.

Equipment with this equipment protection level is intended for use in underground mines and surface installations of such mines endangered by the possible presence of firedamp and/or combustible dust (group I equipment) or at the objects and/or its parts (group II and III equipment) where explosive atmosphere is likely to present in the form of gas, vapour, dust, fibres, or flyings.

4.             Equipment protection level  «equipment protection by increased safety» («increased safety») is applied to equipment intended for use in accordance with the operational parameters specified by the manufacturer and which ensures functioning only in normal operation mode specified by the manufacturer.

Group I equipment with this equipment protection level shall be provided with the means of safe shutdown when the specified concentration of the firedamp in the surrounding atmosphere achieves.

Equipment with this equipment protection level is intended for use in underground mines and surface installations of such mines (group I equipment) where firedamp and/or combustible dust or explosive atmosphere created by the mixture with air in the form of gas, vapour, dust, fibres, or flyings is not likely to occur in normal operation, but if it does occur, will persist for a short period only.

IV. Types of protection of equipment

1. Depending on the special measures applied to prevent ignition of the surrounding explosive atmosphere one type or combination of several types of explosion protection may be applied to:

1)           electrical equipment intended for use in explosive gas atmospheres:

"d" – flameproof enclosure;

"е" – increased safety;

"i" ("ia", "ib", "ic") – intrinsic safety (intrinsically safe electric circuit);

"m" ("mа", "mb", "mс") –encapsulation by compound;

"nА" – non-sparking equipment;

"nС" - enclosed-break devices, hermetically-sealed device or non-incendive components producing arcs, sparks or hot surfaces;

"nR" - restricted-breathing enclosure;

"nL" - energy-limited apparatus;

"nZ" – pressurized enclosure;

"о" - oil immersion;

"р" ("рх", "ру", "pz") - pressurization;

"q" - powder filling;

"s" - special protection;

2)           electrical equipment intended for use in explosive dust atmospheres:

"t" ("ta", "tb", "tc") – protection by enclosure;

"i" ("ia", "ib") - intrinsic safety (intrinsically safe electric circuit);

"m" ("ma", "mb", "mc") - encapsulation;

"p" - pressurization;

"s" - special protection;

3)            non-electrical equipment intended for use in explosive atmospheres:

"с" – protection by constructional safety;

"b" - protection by control of ignition source;

"k" – protection by liquid immersion;

"d" – protection by flameproof enclosure;

"fr" - Protection by flow restricting enclosure;

"р" - pressurization;

4)          other recognized types of explosion protection.

2. The types of explosion protection of equipment are determined by the following special measures, applied to equipment with different levels of protection to avoid ignition of a surrounding explosive atmosphere:

1)    flameproof enclosure "d" - type of protection in which the parts capable of igniting an explosive gas atmosphere are provided with an enclosure which can withstand the pressure developed during an internal explosion of an explosive mixture, and which prevents the transmission of the explosion to the explosive gas atmosphere;

2)    dust ignition protection type «t» - type of protection whereby all equipment is protected by an enclosure to avoid ingress of dust and by means of surface temperature limitation;

3)    increased safety "е"  -  type of protection in which additional measures are applied so as to give increased security against the possibility of excessive temperatures and of the occurrence of arcs and sparks in normal service or under specified (abnormal) conditions;

4)    intrinsic safety (intrinsically safe electric circuit)  "i"  -  type of protection based on restriction of electrical energy (power) of electrical discharge and temperature of the components of electrical equipment  to a level below that which can cause ignition by either sparking or heating effects ;

5)    encapsulation “m” - type of protection whereby parts that are capable of igniting an explosive atmosphere by either sparking or heating are enclosed in a compound in such a way that the explosive atmosphere cannot be ignited under operating or installation conditions;

6)    type of protection "n"  - type of protection applied to electrical apparatus such that, in normal operation and in certain specified (abnormal) conditions, it is not capable of igniting a surrounding explosive gas atmosphere;

7)    oil immersion "о" - type of protection in which the equipment or parts of the equipment are immersed in a protective liquid in such a way that an explosive gas atmosphere which may be above the liquid or outside the enclosure cannot be ignited;

8)    pressurization "р" – type of protection for guarding against the ingress of the external atmosphere into an enclosure or room by maintaining a protective gas therein at a pressure above that of the external atmosphere;

9)    powder filling "q" – type of protection in which the parts capable of igniting an explosive atmosphere are fixed in position and completely surrounded by filling material to prevent ignition of an external explosive atmosphere;

10)                 special protection “s” – type of protection based on the measures of protection other than those specified in items1-9 of the present clause, but which are considered to be sufficient to ensure explosion safety during assessment or tests;

11)                 constructional safety "с" – type of ignition protection in which constructional measures are applied so as to protect against the possibility of ignition from hot surfaces, sparks and adiabatic compression generated by moving parts;

12)   protection by control of ignition source 'b' – type of explosion protection by means of installation in non-electrical equipment of a device, which prevents creation of ignition source and whereby integral sensors detect impending operation and initiate operation of automatic protective and signal devices.

13)   liquid immersion 'k' - a type of protection in which potential ignition sources are made ineffective or separated from the explosive atmosphere by either totally immersing them in a protective liquid, or by partially immersing and continuously coating their active surfaces with a protective liquid in such a way that an explosive atmosphere which may be above the liquid, or outside the equipment enclosure cannot be ignited.

14)   Protection by flow restricting enclosure "fr"   -  type of ignition protection which, by means of an enclosure, reduces the probability of ingress of a surrounding explosive atmosphere into the enclosure to an acceptably low level so that the concentration inside the enclosure is below the lower explosive limit.

V. Temperature classification of equipment

Group II equipment is classified according to the maximum permissible surface temperature as follows:

1)  Т1 - 450 degrees Celsius;

2)  Т2 - 300 degrees Celsius;

3)  ТЗ - 200 degrees Celsius;

4)  Т4 - 135 degrees Celsius;

5)  Т5 - 100 degrees Celsius;

6)  Т6 - 85 degrees Celsius.

ТР ТС 012/2011

Annex  2

to the Technical Regulation of

the Customs union «On safety of

equipment intended for use in

explosive atmospheres»

 (ТР ТС 012/2011)

Drawing of special Explosion Safety Mark