ATEX Terms and Definitions

ATEX Terms and Definitions

This glossary provides definitions for key terms used throughout ATEX documentation, standards, and workplace safety. Terms are organised alphabetically for quick reference.

A

Accreditation

Formal recognition that a conformity assessment body is competent to perform specific tasks. Notified bodies are typically accredited to EN ISO/IEC 17065.

ATEX

From French "ATmosphères EXplosibles". Refers to the EU regulatory framework covering equipment and workplaces where explosive atmospheres may occur. See What is ATEX?

ATEX Equipment Directive

Directive 2014/34/EU covering equipment and protective systems intended for use in potentially explosive atmospheres. See The Two ATEX Directives Explained.

ATEX Workplace Directive

Directive 1999/92/EC setting minimum requirements for worker safety in explosive atmospheres. See The Two ATEX Directives Explained and Employer Duties Under ATEX.

Auto-ignition Temperature (AIT)

The lowest temperature at which a substance will spontaneously ignite without an external ignition source. Critical for determining temperature class requirements.

C

Cable Gland

A fitting that secures and seals cables where they enter enclosures. Must be certified for the protection type and correctly sized for the cable. See Cables in Hazardous Areas.

Category (Equipment)

Classification indicating the level of protection provided by ATEX equipment. Categories 1, 2, and 3 for Group II; M1 and M2 for Group I mining equipment. See Equipment Categories Explained.

CE Marking

Marking indicating conformity with applicable EU legislation. Required on ATEX equipment before placing on the EU market. See ATEX Marking Requirements.

Close Inspection

Inspection grade that includes visual inspection plus checks requiring access tools, but without opening enclosures. See Inspection Grades.

Combustible Dust

Finely divided solid particles that can form an explosive atmosphere when dispersed in air. Subject to Zone 20/21/22 classification. See Introduction to Zone Classification.

Component

An item essential to safe functioning of equipment but with no autonomous function. Must be incorporated into complete equipment before use. See Components vs Equipment.

Conformity Assessment

The process of demonstrating that a product meets applicable requirements. Procedures vary by equipment category. See Conformity Assessment Overview.

D

Declaration of Conformity

Document issued by the manufacturer declaring that a product meets all applicable requirements. Enables CE marking. See Conformity Assessment Overview.

Detailed Inspection

The most thorough inspection grade, including opening enclosures and using test equipment. See Inspection Grades.

Directive 1999/92/EC

See ATEX Workplace Directive.

Directive 2014/34/EU

See ATEX Equipment Directive.

Dust Ignition Protection

Protection methods for equipment in combustible dust atmospheres, including Ex t (protection by enclosure). See Protection Types Overview.

E

Encapsulation (Ex m)

Protection type where parts that could ignite an explosive atmosphere are enclosed in a compound to prevent contact with the atmosphere. See Protection Types Overview.

EPD (Explosion Protection Document)

Document required by the Workplace Directive demonstrating that explosion risks have been assessed and adequate measures taken. See What is an EPD?

EPL (Equipment Protection Level)

Level of protection assigned to equipment based on likelihood of becoming an ignition source. Ga/Da/Ma for highest, Gb/Db/Mb for high, Gc/Dc for enhanced. See Reading ATEX Labels.

Equipment Group

Classification dividing ATEX equipment into Group I (mining) and Group II (surface industries). See Equipment Groups I and II.

EU-Type Examination (Module B)

Conformity assessment procedure where a notified body examines design and tests specimens. Required for Category 1 and 2 equipment. See EU-Type Examination.

Ex d

See Flameproof Enclosure.

Ex e

See Increased Safety.

Ex i

See Intrinsic Safety.

Ex m

See Encapsulation.

Ex n

Type of protection "n" for Zone 2 only, encompassing various techniques including non-sparking, restricted breathing, and energy-limited apparatus.

Ex o

See Oil Immersion.

Ex p

See Pressurised Enclosure.

Ex q

See Powder Filling.

Ex t

Protection by enclosure for dust atmospheres, preventing dust ingress and limiting surface temperature.

Explosive Atmosphere

A mixture with air of flammable substances (gas, vapour, mist, or dust) in which combustion spreads to the entire unburned mixture after ignition. See What is an Explosive Atmosphere?

Explosive Limits

See LEL and UEL.

F

Firedamp

Methane occurring naturally in coal mines. Group I equipment is specifically designed for firedamp hazards.

Flameproof Enclosure (Ex d)

Protection type where an enclosure can withstand an internal explosion and prevent it from igniting the surrounding atmosphere through gaps. See Flameproof Enclosures (Ex d).

Flamepath

The gap between mating surfaces of a flameproof enclosure through which internal explosion products must travel to reach the external atmosphere. Dimensions are critical to safety.

Flash Point

The lowest temperature at which a liquid produces sufficient vapour to form an ignitable mixture with air. See Gases, Vapours and Mists.

G

Gas Group

Classification of gases/vapours by their explosion characteristics. Group IIA (e.g., propane), IIB (e.g., ethylene), IIC (e.g., hydrogen—most hazardous). See Equipment Groups I and II and Reading ATEX Labels.

Group I

Equipment category for underground mines and their surface installations endangered by firedamp and/or combustible dust. See Equipment Groups I and II.

Group II

Equipment category for all other places (surface industries) where explosive atmospheres may occur. Subdivided into IIA, IIB, and IIC by gas group. See Equipment Groups I and II.

H

Harmonised Standard

European standard referenced in the Official Journal that provides presumption of conformity with directive requirements. See Key ATEX Standards.

Hazardous Area

A location where an explosive atmosphere may occur in quantities requiring special precautions. Classified into zones.

I

IEC 60079 Series

International standards for electrical equipment in explosive atmospheres, forming the technical basis for ATEX harmonised standards. See Key ATEX Standards.

IECEx

International certification scheme for equipment in explosive atmospheres, using IEC 60079 standards. See ATEX Beyond Europe.

Ignition Source

Any source of energy capable of igniting an explosive atmosphere: hot surfaces, flames, sparks, electrical arcs, static discharge, etc.

Importer

Any person established in the EU who places a product from a third country on the EU market. Has specific obligations under ATEX. See Importer Obligations.

Increased Safety (Ex e)

Protection type applying measures to prevent sparks, arcs, or excessive temperatures occurring in normal operation. See Protection Types Overview.

Ingress Protection (IP)

Rating system indicating protection against solid objects and water. Important for dust protection (Ex t) and maintaining equipment integrity.

Intrinsic Safety (Ex i)

Protection type limiting electrical energy to levels below those capable of causing ignition. "ia" for Zone 0, "ib" for Zone 1. See Protection Types Overview.

L

LEL (Lower Explosive Limit)

The minimum concentration of a flammable substance in air below which the mixture cannot be ignited. Also called LFL (Lower Flammable Limit). See What is an Explosive Atmosphere?

M

M1 Category

Group I equipment that can remain energised in the presence of an explosive atmosphere. Requires two independent protection means.

M2 Category

Group I equipment intended to be de-energised when an explosive atmosphere is detected.

Machinery Directive

Directive 2006/42/EC covering general machinery safety. Often applies alongside ATEX for machines in hazardous areas. See ATEX and the Machinery Directive.

Manufacturer

Any person who manufactures a product or has it designed/manufactured and markets it under their name or trademark. Bears primary responsibility for ATEX compliance. See Manufacturer Obligations.

Market Surveillance

Activities by national authorities checking conformity of products on the market and taking action against non-compliant products.

Minimum Ignition Energy (MIE)

The lowest electrical spark energy capable of igniting an explosive atmosphere. Critical for intrinsic safety design.

Mist

Fine liquid droplets suspended in air, capable of forming an explosive atmosphere. See Gases, Vapours and Mists.

Module (Conformity Assessment)

A conformity assessment procedure or combination of procedures. Module A (internal control), Module B (type examination), Module D (quality assurance), etc. See Conformity Assessment Overview.

N

NANDO

New Approach Notified and Designated Organisations database listing all notified bodies and their scope of notification.

Non-Electrical Equipment

Mechanical equipment that may present ignition hazards through hot surfaces, friction, or sparks. Also covered by ATEX. See Non-Electrical Equipment in ATEX.

Notified Body

Independent conformity assessment body authorised by an EU Member State to perform certification under ATEX. See What are Notified Bodies?

O

Oil Immersion (Ex o)

Protection type where electrical equipment is immersed in oil to prevent contact with explosive atmosphere. See Protection Types Overview.

P

Powder Filling (Ex q)

Protection type where equipment is filled with powder (e.g., quartz sand) to prevent ignition of surrounding atmosphere. See Protection Types Overview.

Pressurised Enclosure (Ex p)

Protection type maintaining internal pressure above atmospheric to prevent entry of explosive atmosphere. See Protection Types Overview.

Presumption of Conformity

Legal presumption that products meeting harmonised standards comply with directive requirements covered by those standards.

Protection Type

Method of construction preventing equipment from igniting explosive atmospheres (Ex d, Ex e, Ex i, etc.). See Protection Types Overview.

Protective System

Device intended to halt incipient explosions or limit explosion effects (flame arresters, suppression systems, relief panels).

R

Risk Assessment

Systematic evaluation of explosion hazards required by the Workplace Directive. See Risk Assessment Fundamentals.

S

Source of Release

A point from which a flammable substance may be released into the atmosphere. Characterised as continuous, primary, or secondary based on frequency/duration.

Static Electricity

Electrical charge accumulation that can discharge as a spark, potentially igniting explosive atmospheres. A significant ignition source in both gas and dust environments.

Surface Temperature

Maximum temperature of equipment surfaces that may contact explosive atmosphere. Must not exceed ignition temperature of substances present. See Temperature Classes.

T

Technical Documentation

Documentation demonstrating how equipment meets essential requirements. Must be retained for 10 years. See Manufacturer Obligations.

Temperature Class (T-Class)

Classification (T1-T6) indicating maximum surface temperature of equipment. T6 (85°C) is most restrictive; T1 (450°C) is least. See Temperature Classes (T1-T6).

U

U Suffix

Marking suffix indicating an Ex component that must be incorporated into complete equipment before installation in hazardous areas. See Reading ATEX Labels.

UEL (Upper Explosive Limit)

The maximum concentration of a flammable substance in air above which the mixture cannot be ignited. Also called UFL (Upper Flammable Limit). See What is an Explosive Atmosphere?

V

Vapour

Gaseous phase of a substance that is normally liquid at ambient conditions. See Gases, Vapours and Mists.

Visual Inspection

Basic inspection grade identifying defects apparent without using tools or opening enclosures. See Inspection Grades.

X

X Suffix

Marking suffix indicating specific conditions of use that must be consulted in certificate or instructions. See Reading ATEX Labels.

Z

Zone

Classification of hazardous areas by likelihood of explosive atmosphere occurrence. See Introduction to Zone Classification.

Zone 0

Area where explosive gas atmosphere is present continuously or for long periods. Requires Category 1 equipment. See Zone 0, 1, 2 for Gases.

Zone 1

Area where explosive gas atmosphere is likely to occur occasionally in normal operation. Requires Category 2 or better. See Zone 0, 1, 2 for Gases.

Zone 2

Area where explosive gas atmosphere is not likely in normal operation, or only for short periods. Can use Category 3. See Zone 0, 1, 2 for Gases.

Zone 20

Area where explosive dust cloud is present continuously or for long periods. Equivalent to Zone 0 for dust. Requires Category 1 equipment.

Zone 21

Area where explosive dust cloud is likely occasionally in normal operation. Equivalent to Zone 1 for dust. Requires Category 2 or better.

Zone 22

Area where explosive dust cloud is not likely in normal operation, or only briefly. Equivalent to Zone 2 for dust. Can use Category 3.

Zone Classification

Process of dividing areas into zones based on likelihood of explosive atmosphere occurrence. Required by employer duties. See Introduction to Zone Classification.