Blog

Key facts about explosion-proof equipment marking

Key facts about explosion-proof equipment marking



Ex proof 2

WorldWideBridge gets many questions about the marking of explosion-proof equipment, and we have prepared an article that details the marking requirements for this type of equipment according to GOST 31441.1-2011 “ Non-electrical equipment for potentially explosive atmospheres”.



According to GOST 31441.1-2011 “ Non-electrical equipment for potentially explosive atmospheres” the equipmentexplosion-proof equipment should be marked in a visible place on the main part of the equipment. The marking must be clear and durable, even in case of possible chemical corrosion.

Equipment Marking

The marking should include:

a) manufacturer’s name and address;

b) equipment type designation;

c) year of equipment manufacture;

d) designation of the group and explosion protection level of equipment (Group I, with Ma or Mb explosion protection levels - for use in underground mines and their surface structures, hazardous as to firedamp and/or combustible dust; Group II, with Ga, Gb, Ge explosion protection levels Group III, with Da, Db, Dc explosion protection levels - for use in hazardous areas of premises and outdoor installations, except for underground mines, pits and their surface structures);

e) designation of explosion protection type indicating that the equipment complies with one or more of the types of explosion protection

The following symbols for the types of explosion protection should be used:

“fr” - enclosure with limited gas passage;

“d” - flameproof enclosure;

“c” - structural safety;

“b” - control of the ignition source;

“p” - high blood pressure;

“k” - liquid immersion;

“g” - inherent safety;

f) designation of group and subgroup of equipment:

“I” - for equipment intended for use in underground mines and their surface structures, hazardous as to firedamp or combustible dust;

“II” or “IIА”, or “IB”, or “IIС” - for equipment intended for use in places with a potentially explosive gas atmosphere, except for mines and their surface structures, hazardous as to firedamp or combustible dust. The letters A, B, C are used if it is prescribed by the standard for a specific type of explosion protection.

If the equipment is intended for use with a specific gas only, the designation “II” must be followed by the chemical formula or name of the gas.

Note - Equipment marked IIB is suitable for use in places where equipment of subgroup IIA is required. Equipment marked IIC is suitable for use in places where equipment of subgroup IIA or IIB is required.

If the equipment is intended for use with a specific gas only, the designation “II” must be followed by the chemical formula or name of the gas.

NOTE - Equipment marked IIB is also suitable for use in places where equipment of subgroup IIA is required. Likewise, equipment marked IIC is also suitable for use in places where equipment of subgroup IIA or IIB is required.

“III” or “IIIА”, or “IIB”, or “IIIС” - for equipment intended for use in places with a potentially explosive dust atmosphere, except for mines and their surface structures, hazardous as to firedamp or combustible dust.

NOTE - Equipment marked IIIB is suitable for use in places where equipment of subgroup IIIA is required. In a similar way, equipment marked IIIC is suitable for use in places where equipment of subgroup IIIA or IIIB is required.

g) for Group II equipment - designation of the temperature class or maximum surface temperature, °C, or both. If both values are included in the marking, then the temperature class should be indicated last in parentheses. The temperature class or maximum surface temperature is not marked on the equipment fittings.

Example - T1 or 350 °C or 350 °C (T1).

Group II equipment with a maximum surface temperature exceeding 450 °C should include only the temperature value.

Example - 600 °C.

Group II equipment intended for use in a specific gas does not need to be marked with a surface temperature value.

For Group III equipment - designation of the maximum surface temperature value, °С, preceded by the T sign; the degree of protection provided by the enclosure.

Example - T110 °C;

Example - IP54.

If the actual maximum surface temperature does not depend directly on the equipment, but mainly on the operating conditions (such as the heated liquid in the pump), then the temperature class or surface temperature is allowed not to be included in the marking. Such situation should be reflected in the marking, and the corresponding information should be provided in the manual for the consumer or the operation manual.

h) ambient temperature designation for Group I, Group II and Group III equipment (if applicable) as shown in Table.

Ambient temperature designation:

Equipment Ambient temperature range during operation Temperature designation
Normal Maximum 40 °С,

Minimum, -20 °С
None
Special To be installed by the manufacturer and indicated in the operation manual or specifying a special range, for example 0 °С  40 °С or X

i) serial number, excluding:

- fittings (bushings, locking plates, fixing plates);

- small-sized equipment with a limited surface (the batch number can be considered as an alternative to the serial number);

j) name or mark of the certification body and certificate number - if the equipment is certified; number of the “technical file” (technical documentation), assigned by the manufacturer - if the equipment is not certified;

k) special conditions for safe use, if necessary. In this case, “X” must be placed after the explosion protection mark or the “technical file” number. A warning notation can be used instead of “X”.

NOTE The manufacturer should provide the consumer with information on the requirements of special conditions for safe use, together with other necessary information contained in the manual for the consumer or in the operation manual;

l) any other additional marking prescribed by the standards for the specific types of explosion protection listed in section 1;

m) any marking required by the specific equipment standards.

If the equipment is intended for use in an explosive atmosphere containing gases, vapors, mists or dust, the marking should include designation of appropriate levels of equipment explosion protection. In case of using different parts of equipment with different types of explosion protection, each corresponding part in the marking must have a designation of the type of explosion protection adopted therefor.

If several types of explosion protection were used in the equipment, designation of the main type of explosion protection is put in the first place, and then that of other types.

On small equipment with a limited surface, the content of the marking can be reduced, but, nevertheless, the marking must include the name or registered trademark of the manufacturer and the following:

a) designation of the explosion protection type;

b) name or mark of the certification body;

c) certificate number;

d) “X” mark, if applicable.

Examples of complete equipment marking

Marking example of non-electrical equipment of Group II, Ga level of explosion protection, certified to meet the requirements of this standard

Example for Group II equipment with Ga explosion protection level for operation in an explosive gas atmosphere for a long time, using two independent types of explosion protection, one of which remains active even in case of rare faults. Two independent types of explosion protection are “structural safety protection “c” with a maximum surface temperature of 135 °C (T4) and “liquid immersion protection “k””:

- manufacturer’s name and address;

- type of equipment and year of manufacture;

- group and explosion protection level of equipment, II Ga ;

- type of explosion protection and temperature class, с/k T4;

- serial number;

name or mark of the certification body and certificate number.

NOTE There is a “/” sign between the two independent types of explosion protection.

Example of marking equipment for Group II, Gb explosion protection level

Example for Group II equipment with Gb explosion protection level for operation in an explosive gas environment using two types of explosion protection on different parts of this equipment. Two types of explosion protection are “structural safety protection “c” with a maximum surface temperature of 135 °C (T4) and “liquid immersion protection “k””:

- manufacturer’s name and address;

- type of equipment and year of manufacture;

- group and explosion protection level of equipment, II Gb ;

- type of explosion protection and temperature class, с/k T4;

- serial number;

- number of the “technical file” of the manufacturer.

NOTE There is no “/” sign between the two combined types of explosion protection.

Examples of equipment explosion protection marking

Example for Group II equipment with Gb explosion protection level and with type of explosion protection “flameproof enclosure” for use in an explosive gas atmosphere with gas of IIB subgroup, temperature class T4:

II Gb d IIBT4

Example for Group II equipment with Gc explosion protection level for use in an explosive gas environment with temperature class T4 without any type of explosion protection:

II Gc T4

Example for Group III equipment with Db explosion protection level and with type of explosion protection “constructional safety” for use in explosive dust environment with a maximum surface temperature of 110 °C and degree of protection IP54:

III Db c T110 °C

IP54

Example for equipment: Group II, Gb level of explosion protection with type of explosion protection “constructional safety “c””, for use in explosive gas atmosphere with temperature class T2 and Group III, Db level of explosion protection with type of explosion protection “constructional safety “c””, for use in potentially explosive dust atmosphere with a maximum surface temperature of 230 °C and degree of protection IP54:

II Gb с Т4

III Db с Т230 °С

IP54

Example for Group II equipment with two levels of explosion protection (for example, for different pieces of equipment):

II Gb d Т3 / Ga with Т2

Consumer Information

The equipment should be supplied with user manual or operation manual, including at least the following:

- summary information included in the marking of the equipment, except for the serial number, as well as any additional relevant information to facilitate maintenance (for example, the address of the supplier, repair service, etc.):

- safety instructions;

- on commissioning;

- on operation;

- on assembly and disassembly;

- on maintenance (inspection, routine and emergency repair);

- on installation;

- on adjustment;

- indications of special hazards arising from the equipment, for example, in hazardous areas in front of pressure relief devices (if necessary);

- instructions for training (if necessary);

- details that allow a decision to be made whether the equipment can be used safely in the intended area and under the expected operating conditions.

NOTE This information is based on an assessment of the ignition hazards.


- values of pressure, maximum surface temperature and other limit values;

- special conditions for safe use, including details of possible misuse based on experience (if necessary);

- main characteristics of auxiliary devices that can complement the equipment (if necessary).

Manual for the consumer or the operation manual should contain information, drawings and diagrams necessary for commissioning, maintenance, inspection, verification of the correct functioning and, if necessary, repair of the equipment, along with recommendations to ensure the explosion safety of its operation.

WorldWideBridge team is always ready to consult you on this matter. Do not hesitate to contact our team. You can also send your inquiry through [email protected]

Read more articles about the certification:

Metrological equipment certification: Primary Verification Case (Poverka)
Safety Case / Safety Justification: two titles but one meaning





Please comment, ask questions and share with colleagues


Latest Posts