ATEX marking structure

ATEX Certificate Marking Structure

To identify and sell explosion-proof goods, the manufacturer must determine the marking of explosion-proof goods based on the technical requirements of the buyer when completing the application for ATEX certification.

Part relevant to EN IEC 60079-0				Part relevant to ATEX directive
equipment protection level (EPL)	Temperature Class	Symbol of equipment group	Type of Explosion Protection	equipment category	equipment group	Hexagon arm
(6)	(5)	(4)	(3)	(2)	(1)

Important notes

The Ex marking for explosive gas atmospheres and explosive dust atmospheres shall be separate and not combined, like the below example:

II 1 G Ex ia IIB T4 Ga
II 1 D Ex ia IIIC T120°C Da

Alternatively, the directive part of the marking may be combined and the standard part of the marking kept separate, like the below example:

II 1 GD Ex ia IIB T4 Ga
Ex ia IIIC T120°C Da

For Ex Equipment intended to be put on the market in the EEA, CE marking is applicable.

For Ex Components intended to be put on the market in the EEA, CE marking is not applicable.

Charachters of ATEX marking

1- Charachters for ATEX directive

the symbol Hexagon: indicates that the desired explosion proof equipment, corresponds to one or more of the types of ATEX protection which are the subject of the specific standards listed in the clause 1 of EN IEC 60079-0:2018.

equipment group

according to ATEX directive, explosion proof products are classified in two below groups:

equipment-group I: equipment intended for use in underground parts of mines, and in those parts of surface installations of such mines, liable to be endangered by firedamp and/or combustible dust, comprising equipment categories M 1 and M 2;
equipment-group II: equipment intended for use in other places (non-mineral and for general industrial explosive atmospheres) liable to be endangered by explosive atmospheres, comprising equipment categories 1, 2 and 3.

equipment category

Means the classification of equipment, within each equipment-group, determining the requisite level of protection to be ensured, including:

Gases: 1G (Zone 0), 2G (Zone 1), 3G (Zone 2)
Dust: 1D (Zone 0), 2D (Zone 1), 3D (Zone 2)

for more information about explosive hazardous areas or zones, click here.

2- Charachters for Standard

2-1- Ex marking for explosive gas atmospheres

Type of Explosion Protection
- Ex da: flameproof enclosures, (for EPL Ga or Ma)
- Ex db: flameproof enclosures, (for EPL Gb or Mb)
- Ex dc: flameproof enclosures, (for EPL Gc)
- Ex eb: increased safety, (for EPL Gb or Mb)
- Ex ec: increased safety, (for EPL Gc)
- Ex ia: intrinsic safety, (for EPL Ga or Ma)
- Ex ib: intrinsic safety, (for EPL Gb or Mb)
- Ex ic: intrinsic safety, (for EPL Gc)
- Ex ma: encapsulation, (for EPL Ga or Ma)
- Ex mb: encapsulation, (for EPL Gb or Mb)
- Ex mc: encapsulation, (for EPL Gc)
- Ex nA: non-sparking, (for EPL Gc)
- Ex nC: protected sparking, (for EPL Gc)
- Ex nR: restricted breathing, (for EPL Gc)
- Ex ob: liquid immersion, (for EPL Gb)
- Ex oc: liquid immersion, (for EPL Gc)
- Ex op is: optical radiation, inherently safe (for EPL Ga or Gb or Gc or Ma or Mb)
- Ex op pr: optical radiation, protected fibre (for EPL Gb or Gc or Mb)
- Ex op sh: optical radiation, interlock (for EPL Ga or Gb or Gc or Ma or Mb)
- Ex pv: pressurization, (for EPL Gb or Gc)
- Ex pxb: pressurization, (for EPL Gb or Mb)
- Ex yb: pressurization, (for EPL Gb)
- Ex pzc: pressurization, (for EPL Gc)
- Ex q: powder filling, (for EPL Gb or Mb)
- Ex sa: special protection (for EPL Ga or Ma)
- Ex sb: special protection (for EPL Gb or Mb)
- Ex sc: special protection (for EPL Gc)

the symbol of the group
- Ex Equipment for mines susceptible to firedamp which is shown by symbol I;
- Ex Equipment for places with an explosive gas atmosphere other than mines susceptible to firedamp which is shown by symbol II, includes:
  - IIA, a typical gas is propane;
  - IIB, a typical gas is ethylene;
  - IIC, typical gases are hydrogen and acetylene.
  - When the Ex Equipment is intended for use only in a particular gas, the chemical formula or the name of the gas should be placed in parentheses.
  - When the Ex Equipment is intended for use in a particular gas in addition to being suitable for use in a specified equipment group, the chemical formula of the particular gas shall be written after the equipment group and be separated with the symbol “+”. for example, “IIB + H2”;

Temperature Class (only for group II equipment)

The temperature class is determined according to the amount of maximum surface or service temperature on the basis of the below table which specifies the corresponding between temperature classes (T1 to T6) and temperature ranges relevant to each temperature class.

For instance, the equipment having a maximum surface or service temperature between 85°C to 100°C falls into temperature class T5.

Note: where the manufacturer wishes to specify a maximum surface temperature between two temperature classes, he may do so by marking that maximum surface temperature in degrees celsius alone, or by marking both that maximum surface temperature in degrees Celsius and, in parentheses, the next highest temperature class, for example, T1 or 350 °C or 350 °C (T1).

Note: Group II Ex Equipment, having a maximum surface temperature greater than 450 °C, shall be marked only with the maximum surface temperature in degrees Celsius, for example, 600 °C.

Ex Equipment with multiple temperature classes or external sources of heating / cooling

the complete temperature class information shall be included in the certificate;
in case if the temperature class includes a range, it shall be shown in the marking with the lower and upper limits of the temperature class separated by “…”, e.g. “T6...T3”.
the mentioned marking in the certificate shall include the symbol “X” to indicate this specific condition of use;

cases of not existence temperature class or maximum surface temperature in ATEX marking

Group II Ex Equipment, marked for use in a particular gas;
Ex Equipment cable glands;
Ex Equipment blanking elements; and
Ex Equipment thread adapters.

equipment protection level (EPL)

EPL for Ex equipment group II

Ga: equipment for explosive gas atmospheres, having a "very high" Level of Protection, which is not a source of ignition in normal operation, during expected malfunctions or during rare malfunctions and usually is a category 1 equipment (used for hazardous Zone 0);
Gb: equipment for explosive gas atmospheres, having a "high" Level of Protection, which is not a source of ignition in normal operation or during expected malfunctions and usually is a category 2 equipment (used for hazardous Zone 1);
Gc: equipment for explosive gas atmospheres, having an "enhanced" Level of Protection, which is not a source of ignition in normal operation and which may have some additional protection to ensure that it remains inactive as an ignition source in the case of regular expected occurrences (for example failure of a lamp) and usually is a category 3 equipment (used for hazardous Zone 2)

EPL for Ex equipment group I

EPL Ma: equipment for installation in a mine susceptible to firedamp, having a "very high" Level of Protection, which has sufficient security that it is unlikely to become an ignition source in normal operation, during expected malfunctions or during rare malfunctions, even when left energized in the presence of an outbreak of gas and usually is a category M1 equipment (hazardous Zone is not applicable for equipment group I)
EPL Mb: equipment for installation in a mine susceptible to firedamp, having a "high" Level of Protection, which has sufficient security that it is unlikely to become a source of ignition in normal operation or during expected malfunctions in the time span between there being an outbreak of gas and the equipment being de-energized (hazardous Zone is not applicable for equipment group I)

Symbol "X" or abnormal ambient temperature range (as appropriate)

Normal ambient temperature range: Equipment designed for use in the range of –20 °C to +40 °C or a reduced range such as -5 ºC ≤ Tamb ≤ 15 ºC.

Ex equipoment with normal ambient temperature range, does not require marking of the ambient temperature range but the equipment with abnormal ambient temperature range is considered as special.

Marking for Ex equipment with special ambient temperature range: The marking shall include either the symbol Ta or Tamb together with both the upper and lower ambient temperatures or, if this is impracticable, the symbol “X“ shall be used to indicate specific conditions of use that include the upper and lower ambient temperatures.

When the ambient temperature range is abnormal, the symbol “X” could be mentioned as the last charachter of ATEX marking to indicate the specific condition of use with the intent that the requirements of the Specific Conditions of Use are passed to the user together with any other relevant information.

An advisory marking may appear on the equipment as an alternative to the requirement for the “X” marking.
A reference to a specific instruction document containing the detailed information may appear on the equipment as an alternative to the requirement for the “X” marking.

Note: If the Ex Equipment is marked for use in both explosive gas and dust atmospheres and the ambient temperature range rating is identical, only one marking of ambient temperature range need appear.

ATEX marking for associated apparatus and Ex associated equipment

associated apparatus

electrical apparatus which contains both intrinsically safe and non-intrinsically safe circuits and is constructed so that the non-intrinsically safe circuits cannot adversely affect the intrinsically safe circuits. Associated apparatus is either:

additionally protected by a Type of Protection suitable for use in the appropriate explosive atmosphere, or
not protected by a Type of Protection suitable for use in the appropriate explosive atmosphere and therefore is not to be used within an explosive atmosphere.

Hazardous area: area in which an explosive atmosphere is present, or may be expected to be present, in quantities such as to require special precautions for the construction, installation and use of equipment.

non-hazardous area: area in which an explosive atmosphere is not expected to be present in quantities such as to require special precautions for the construction, installation and use of equipment.

Marking of the associated apparatus

#	suitability for installation in hazardous area	Source of providing energy limitation	Similarities or differences between groups	Marking Style	Example(s)
1	suitable	inside the Ex Equipment in the hazardous area	equipment group of the associated apparatus is similar to the associated apparatus.	the symbols for the Level of Protection and EPL shall be enclosed within square brackets	Ex db [ia Ga] IIC T4 Gb or a shunt diode safety barrier located inside a flameproof enclosure
2	suitable	inside the Ex Equipment in the hazardous area	the equipment group of the associated apparatus differs from that of the Ex equipment.	the symbols for the Level of Protection, EPL and the equipment group of the associated apparatus shall be enclosed within square brackets.	Ex db [ia IIC Ga] IIB T4 Gb

3	suitable	outside the Ex Equipment in the hazardous area	---	the symbols for the Type of Protection shall not be enclosed within square brackets.	Ex db ia IIC T4 Gb a flameproof luminaire with an intrinsically safe photocell connected to a safe area Note: the equipment group of the Ex equipment and associated apparatus shall be the same.

4	not suitable	---	---	the symbol Ex and the symbol for the Level of Protection and EPL shall be enclosed within the same square brackets. the temperature class is not included	[Ex ia Ga] IIC Note: The reason there is no character to the left of the bracket in the marking is that the associated apparatus is not intended for use in a hazardous area and only its output is connected to the hazardous area. For example, a power supply with a barrier connected to it which are located in the safe area.

end of table.

Marking of the “associated apparatus” for Ex Equipment in special case (includes both associated apparatus and intrinsically safe apparatus; and with no connections required to be made to the intrinsically safe part of the Ex Equipment by the user)

#	Similarities or differences between EPLs	Marking style	Correct example	Incorrect example
1	similar EPLs	the “associated apparatus” marking shall not appear	Ex db ib IIC T4 Gb	Ex db ib [ib Gb] IIC T4 Gb
2	different EPLs	the “associated apparatus” marking shall appear	Ex db ib [ib Gb] IIC T4 Gb	Ex db ib IIC T4 Gb

end of table.

Ex associated equipment

auxiliary equipment used in conjunction with explosion-protected equipment to maintain specific aspects of the Type of Protection of the explosion-protected equipment.

Examples

special time/current
relays for increased safety motors;
pressurization control systems;
power limits for encapsulated Ex Equipment.

Ex associated equipment is either

additionally protected by a type of Protection suitable for use in the appropriate explosive atmosphere; or
not protected by a type of Protection suitable for use in the appropriate explosive atmosphere and therefore is not to be used within an explosive atmosphere.

Marking of Ex associated equipment

#	suitability for installation in hazardous area	Providing only Ex associated equipment or with associated apparatus	Marking Style	Example(s)
1	suitable	only Ex associated equipment is provied	the symbols for the Level of Protection of the Ex associated equipment and the EPL shall be enclosed within square brackets	Ex db [pxb Gb] IIC T4 Gb a control box (unit) with the protection of Ex pxb Gb which is placed inside an Exd enclosure in the hazardous area (associated equipment) and connected to a Exp container (Ex equipment) which has been installed in an hazardous area too.
2	suitable	both associated apparatus and associated equipment are provided	the symbols for the Levels of Protection and EPL are shown within separate square brackets	Ex db [ib Gb] [pxb Gb] IIC T4 Gb a control box (unit) with the protection of Ex pxb Gb (associated equipment) together with a barrier (associated apparatus) which are placed inside an Exd enclosure in an hazardous area and connected to a Exp container (Ex equipment) which has been installed in an hazardous area too.

3	not suitable	only Ex associated equipment is provied	the symbol Ex and the symbol for the Level of Protection of the Ex associated equipment and the EPL shall be enclosed within the same square brackets and no temperature class include.	[Ex pxb Gb] a control box (unit) with the protection of Ex pxb Gb (associated equipment) which is placed inside a non explosion proof enclosure in the non-hazardous (safe) area and connected to a container with Exp protection (Ex equipment) which has been installed in a hazardous area.
4	not suitable	both associated apparatus and associated equipment are provided	the symbols for the Levels of Protection and EPL are shown within separate square brackets and no temperature class include.	[Ex ib Gb] [Ex pxb Gb] IIC a control box (unit) with the protection of Ex pxb Gb (associated equipment) together with a barrier (associated apparatus) which are placed inside a non explosion proof enclosure in the non-hazardous (safe) area and connected to a container with Exp protection (Ex equipment) which has been installed in a hazardous area.

end of table.

Where the equipment group is different for the Ex associated equipment and the Ex Equipment, the Equipment Group shall also be shown for example, Ex db [ib IIC Gb] [pxb Gb] IIB T4 Gb.

Differences between associated apparatus and associated equipment

associated apparatus is an electrical device which has been formed of an intrinsically safe current and a non-Ex current;
associated apparatus has not an independent function but associated eqipment has independent function;
the ATEX marking for associated apparatus is considered as a part of a complete marking for the relevant Ex equipment but an associated equipment has a specific independent ATEX marking.

2-2- Ex marking for explosive dust atmospheres

ATEX marking structure

ATEX marking structure

ATEX Certificate Marking Structure

To identify and sell explosion-proof goods, the manufacturer must determine the marking of explosion-proof goods based on the technical requirements of the buyer when completing the application for ATEX certification.

Part relevant to EN IEC 60079-0

Part relevant to ATEX directive

equipment protection level (EPL)

Temperature Class

Symbol of equipment group

Type of Explosion Protection

equipment category

equipment group

Hexagon arm

(6)

(5)

(4)

(3)

(2)

(1)

Important notes

The Ex marking for explosive gas atmospheres and explosive dust atmospheres shall be separate and not combined, like the below example:

II 1 G Ex ia IIB T4 Ga II 1 D Ex ia IIIC T120°C Da

Alternatively, the directive part of the marking may be combined and the standard part of the marking kept separate, like the below example:

II 1 GD Ex ia IIB T4 Ga Ex ia IIIC T120°C Da

For Ex Equipment intended to be put on the market in the EEA, CE marking is applicable.

For Ex Components intended to be put on the market in the EEA, CE marking is not applicable.

Charachters of ATEX marking

1- Charachters for ATEX directive

the symbol Hexagon: indicates that the desired explosion proof equipment, corresponds to one or more of the types of ATEX protection which are the subject of the specific standards listed in the clause 1 of EN IEC 60079-0:2018.

equipment group

according to ATEX directive, explosion proof products are classified in two below groups:

equipment-group I: equipment intended for use in underground parts of mines, and in those parts of surface installations of such mines, liable to be endangered by firedamp and/or combustible dust, comprising equipment categories M 1 and M 2;

equipment-group II: equipment intended for use in other places (non-mineral and for general industrial explosive atmospheres) liable to be endangered by explosive atmospheres, comprising equipment categories 1, 2 and 3.

equipment category

Means the classification of equipment, within each equipment-group, determining the requisite level of protection to be ensured, including:

Gases: 1G (Zone 0), 2G (Zone 1), 3G (Zone 2)

Dust: 1D (Zone 0), 2D (Zone 1), 3D (Zone 2)

for more information about explosive hazardous areas or zones, click here.

2- Charachters for Standard

2-1- Ex marking for explosive gas atmospheres

Type of Explosion Protection

Ex da: flameproof enclosures, (for EPL Ga or Ma)

Ex db: flameproof enclosures, (for EPL Gb or Mb)

Ex dc: flameproof enclosures, (for EPL Gc)

Ex eb: increased safety, (for EPL Gb or Mb)

Ex ec: increased safety, (for EPL Gc)

Ex ia: intrinsic safety, (for EPL Ga or Ma)

Ex ib: intrinsic safety, (for EPL Gb or Mb)

Ex ic: intrinsic safety, (for EPL Gc)

Ex ma: encapsulation, (for EPL Ga or Ma)

Ex mb: encapsulation, (for EPL Gb or Mb)

Ex mc: encapsulation, (for EPL Gc)

Ex nA: non-sparking, (for EPL Gc)

Ex nC: protected sparking, (for EPL Gc)

Ex nR: restricted breathing, (for EPL Gc)

Ex ob: liquid immersion, (for EPL Gb)

Ex oc: liquid immersion, (for EPL Gc)

Ex op is: optical radiation, inherently safe (for EPL Ga or Gb or Gc or Ma or Mb)

Ex op pr: optical radiation, protected fibre (for EPL Gb or Gc or Mb)

Ex op sh: optical radiation, interlock (for EPL Ga or Gb or Gc or Ma or Mb)

Ex pv: pressurization, (for EPL Gb or Gc)

Ex pxb: pressurization, (for EPL Gb or Mb)

Ex yb: pressurization, (for EPL Gb)

Ex pzc: pressurization, (for EPL Gc)

Ex q: powder filling, (for EPL Gb or Mb)

Ex sa: special protection (for EPL Ga or Ma)

Ex sb: special protection (for EPL Gb or Mb)

Ex sc: special protection (for EPL Gc)

the symbol of the group

Ex Equipment for mines susceptible to firedamp which is shown by symbol I;

Ex Equipment for places with an explosive gas atmosphere other than mines susceptible to firedamp which is shown by symbol II, includes:

IIA, a typical gas is propane;

IIB, a typical gas is ethylene;

IIC, typical gases are hydrogen and acetylene.

When the Ex Equipment is intended for use only in a particular gas, the chemical formula or the name of the gas should be placed in parentheses.

When the Ex Equipment is intended for use in a particular gas in addition to being suitable for use in a specified equipment group, the chemical formula of the particular gas shall be written after the equipment group and be separated with the symbol “+”. for example, “IIB + H2”;

Temperature Class (only for group II equipment)

The temperature class is determined according to the amount of maximum surface or service temperature on the basis of the below table which specifies the corresponding between temperature classes (T1 to T6) and temperature ranges relevant to each temperature class.

For instance, the equipment having a maximum surface or service temperature between 85°C to 100°C falls into temperature class T5.

Note: Group II Ex Equipment, having a maximum surface temperature greater than 450 °C, shall be marked only with the maximum surface temperature in degrees Celsius, for example, 600 °C.

II 1 G Ex ia IIB T4 Ga
II 1 D Ex ia IIIC T120°C Da

II 1 GD Ex ia IIB T4 Ga
Ex ia IIIC T120°C Da