Decoding Hazardous Area Exproof Certification Markings

Many industrial facilities contain flammable gases, vapors, or dust. In these environments, using the wrong equipment can have serious consequences. Exproof refers to equipment that is certified for safe use in these hazardous environments. Most engineers and specifiers recognize the Ex marking as a sign that a product is certified for hazardous areas. However, interpreting what each symbol, letter, and number actually means can be confusing, even for experienced engineers. Misreading can lead to incorrect equipment selection, regulatory non-compliance, increased project costs, or unsafe installation.

An Exproof label carries critical information in a compact format. It tells you which hazardous atmosphere the equipment is certified for, which protection concept is applied, which gas or dust group it covers, the maximum permitted surface temperature, the ambient temperature range, and the area classification where it can be safely installed. There are two main certification systems used globally. European and international facilities follow ATEX and IECEx standards. Facilities in the United States and Canada follow the NEC/CEC system certified by UL and cUL.

 

European Standard: ATEX and IECEx

The ATEX and IECEx system classifies hazardous areas into zones. Zones define both the type of explosive atmosphere and the likelihood of it being present.

• Zone 0 and Zone 20 indicate an explosive atmosphere present continuously or for long periods.
• Zone 1 and Zone 21 indicate an explosive atmosphere likely to occur in normal operation.
• Zone 2 and Zone 22 indicate an explosive atmosphere not likely to occur in normal operation but that may be present for short periods.
• Zones 0, 1, and 2 apply to gases, vapors, and mists.
• Zones 20, 21, and 22 apply to dust.

The equipment marking follows a structured format:

• The equipment group and category indicate where the equipment can be used and what level of protection it provides.
• The type of explosive atmosphere tells you whether the equipment is certified for gases, vapors, or mists (G) or for dust (D).
• The protection concept describes how the equipment prevents ignition.
• The apparatus group defines which specific gases the equipment is approved for.
• The temperature class indicates the maximum surface temperature the equipment can reach.
• The ambient temperature range shows the operating temperature limits.
• The IP rating indicates protection against dust and water ingress.
• Certificate numbers for both ATEX and IECEx are shown separately on the label.

 

US and Canada Standard: UL and cUL

The NEC/CEC system used in the United States and Canada uses a different structure but serves the same purpose.

• Classes define the type of hazardous material present.
• Class I covers flammable gases or vapors.
• Class II covers combustible or electrically conductive dust.
• Class III covers easily ignitable fibers or flyings.

Divisions define the likelihood of the hazardous atmosphere being present.

• Division 1 means the hazard exists or is likely to exist under normal conditions.
• Division 2 means the hazard does not normally exist but may appear under abnormal conditions.

In the USA, installations can use either the Class/Division or the Class/Zone system.
In Canada, new installations must now use the Class/Zone system. Existing installations in Canada may use either system.

The equipment label shows:

• The class and division classification indicates the type of hazardous material present and the likelihood of it being present.
• The temperature class indicates the maximum surface temperature the equipment can reach.
• The ambient temperature range shows the operating temperature limits.
• The UL mark confirms the product is listed for use in the United States and Canada.
• The enclosure type indicates the level of physical protection the housing provides.

 

ATEX/IECEx and US/Canada Classification Comparison

ATEX Equipment Group	ATEX Equipment Category and Environment Type	Zone Classification ATEX/IECEx	Required Equipment Protection Level (EPL)	Class/Zone Classification US/Canada	Class/Division Classification US/Canada
I	M1	N/A	Ma	N/A	Mining
	M2		Mb
II	1G	Zone 0	Ga	Class 1, Zone 0	Class I, Division 1
	2G	Zone 1	Gb	Class 1, Zone 1
	3G	Zone 2	Gc	Class 1, Zone 2	Class I, Division 2
	1D	Zone 20	Da	Class 1, Zone 20	Class II, Division 1
	2D	Zone 21	Db	Class 11, Zone 21
	3D	Zone 22	Dc	Class 11, Zone 22	Class II, Division 2, Class III

 

Cedetaş Engineering as Your Solution Partner

Selecting the right Exproof equipment requires understanding both your facility and the equipment. Cedetaş Engineering & Technology can guide you in equipment selection and procurement. Contact us to discuss your requirements.