ATEX Glossary

Glossary Word ATEX Glossary Description
ATEX Term used to describe the legal requirement for explosive atmospheres in Europe (or a contract specification outside Europe). May refer to equipment (ATEX 95) or the protection of Workers from Potentially Explosive Atmospheres (ATEX 137) depending on the context.
ATEX 95 (Atmosphere Explosive): Mandatory Legislation from July 1:’2003 covering electrical, non-electrical and protective safety systems used to prevent or limit the effects of an explosion caused by the ignition of a gas or dust explosive atmosphere.
DSEAR UK Implementation ATEX 137. Dangerous Substances and Explosive Atmosphere Regulations:
Mandatory legislation commenced December 2002 incorporating the Chemicals Agents Directive (CAD) and the Protection of Workers from Potentially Explosive Atmospheres (Directive ATEX137).
ATEX 137 Mandatory Legislation in Europe from July 2006 for the Protection of Workers from Potentially Explosive Atmospheres.
Ex Equipment Equipment that has been certified for use in a Potentially Explosive Atmosphere. Pre-ATEX only covered electrical ignitions and gas atmospheres. ‘Ex’ Equipment can be ignition capable if the concept is designed to contain an explosion, such as Ex’d’
Ignition Risk Assessment The likelihood that ignition sources will be present and become active and effective, the installations, work processes and substances used their possible interactions and the scale of the anticipated effects
Area Classification The likelihood that explosive atmospheres will occur and their persistence. Places that are or can be connected via openings to places in which explosive atmospheres may occur shall be taken into account in assessing explosion risks.
Flashpoint The temperature at which a liquid will form a flammable atmosphere.
Detonation A violent explosion, flame front speed 200-3000 m/sec, speed of sound 330 m/sec
Zone 0 A location where an explosive atmosphere consisting of a mixture of air or flammable substances in the form of a gas, vapour or mist is likely to occur continuously or long periods.
Zone 1 A location where an explosive atmosphere consisting of a mixture of air or flammable substances in the form of a gas, vapour or mist is likely to occur in normal operation occasionally.
Zone 2 A location where an explosive atmosphere consisting of a mixture of air or flammable substances in the form of a gas, vapour or mist is likely to occur in abnormal operation occasionally.
Zone 20 A location where an explosive atmosphere consisting of a mixture of air and flammable substances in the form of dust is present continuously or for long periods
Zone 21 A location where an explosive atmosphere consisting of a mixture of air and flammable substances in the form of dust is likely to occur in normal operation occasionally
Zone 22 A location where an explosive atmosphere consisting of a mixture of air and flammable substances in the form of dust is not likely to occur in normal operation but if it does it will persist for a short period only
IP15 Institute of Petroleum Model code of Safe Practice Part 15 (Petroleum Products).
AEx North American NEC 505 Explosion protected Equipment.
Ex IEC or ATEX Explosion Protected Equipment.
Notified Body A body that has been audited and accepted by the Government of the country of Notification and Europe. Notified Bodies are frequently mandated for certain directives such as ATEX and PED and may also be required for other Directives where the manufacturer can not comply with the required European Standard.
CE Conformity European – indicates that a product complies will all current European Directives (and normally the applicable European Standards) at the ‘current’ state (on the day it was put in to supply). CE is NOT a safety mark; it is a passport system for accessing markets in Europe.
Risk Assessment Determining by systematic examination the overall system risk by evaluating the frequency and consequences of hazards.
Distinctive Community Mark A mark that indicates explosion protection has been applied for Europe
under the ATEX Directive. Prior to ATEX the mark could only be applied
by a Notified Body, since 2003, people who self certify can also apply
the mark.
Flameproof
EEx d
Ex d
AEx d
Explosion proof
The equipment is contained within an enclosure which will withstand an internal explosion of a flammable gas or vapour that may enter it, without suffering damage and without communicating the internal explosion to the external explosive atmosphere, through any joints or structural openings in the enclosure. Equipment designed to this concept is suitable for use in “Zone 1” and “Zone 2” classified hazardous areas.
Intrinsic safety
i.s.
EEx ‘ia’
EEx ‘ib’
Ex ‘ia’
Ex ‘ib’
AEx ‘ia’
AEx ‘ib’
A protection technique based upon the restriction of electrical energy within the apparatus and in the interconnecting wiring, exposed to a explosive atmosphere, to a level below that can cause ignition by either sparking or heating effects.
Because of the method by which intrinsic safety is achieved it is necessary that not only the electrical apparatus exposed to the explosive atmosphere, but also other (associated) electrical apparatus with which it is interconnected, is suitably constructed.
The concept is divided into two sub types, which are dependent upon the number of allowable fault conditions. The symbols ‘ia’ and ‘ib’ denote the sub types.
This design concept is reflected in the equipment making by the symbols Ex ‘ia’ or Ex ‘ib’.
Equipment designed to this concept is suitable for use in: ‘EX ia’ ‘Zone 0’, ‘Zone 1’ and ‘Zone 2’; ‘Ex ib’ ‘Zone 1’ and ‘Zone 2’ classified hazardous areas.
Increased Safety
EEx e
Ex e
AEx e
Additional measures are applied to an electrical apparatus to give increased security against the possibility of excessive temperatures and of the occurrence of arcs and sparks during the life of the apparatus.
It applies only to an electrical apparatus, no parts of which produce sparks, arcs, or exceeds the limiting temperature of the materials, upon which safety depends, that are used in its construction. Equipment designed to this concept is suitable for use in ‘Zone 1’ and ‘Zone 2’ classified hazardous areas.
Purge
Pressurisation
EEx p
eX P aeX P
A method of protection using the pressure of a protective gas to prevent the ingress of an explosive atmosphere to a space that may contain a source of ignition and were necessary, using continuous dilution of an atmosphere within the space that contains a source of emission gas, which may form an explosive atmosphere.
This design concept is reflected in the equipment making by the symbol Ex ‘p’.
Equipment designed to this concept is suitable for use in ‘Zone 1’ and ‘Zone 2’ classified hazardous areas.
Non-sparking
EEx n
Ex n
A type of protection applied to an electrical apparatus such that, in normal operation, it is not capable of igniting a surrounding explosive atmosphere.
Equipment designed to this concept is suitable for use in ‘Zone 2’ classified hazardous areas. Breaks down to several concepts, nL, nA, nC and nR.
Encapsulation
EEx maE
Ex mb
EEx mc
A type of protection in which parts that could ignite an explosive atmosphere by either sparking or heating are enclosed in a compound in such a way that the explosive atmosphere cannot be ignited. The compound provides a barrier between the electrical apparatus and the explosive atmosphere.
Equipment designed to this concept is suitable for use in ‘Zone 0’, ‘Zone 1’ and ‘Zone 2’ classified hazardous areas.
Oil Immersion
EEx o
Ex o
A method of protection where the electrical apparatus is made safe by oil-immersion. In the sense that an explosive atmosphere above the oil or outside the enclosure will not be ignited. The oil presents a barrier between the explosive atmosphere and the electrical apparatus.
Equipment designed to this concept is suitable for use in ‘Zone 1’ and ‘Zone 2’ classified hazardous areas.
Powder Filled
EEx q
Ex q
A method of protection where the enclosure of the electrical apparatus is filled with a mass of granular material such that, if an arc occurs the arc will not be liable to ignite the external explosive atmosphere.
Equipment designed to this concept is suitable for use in ‘Zone 1’ and ‘Zone 2’ classified hazardous areas.
CAT 1 A special form of protection and a Standard for the highest risk equipment, CAT 1 can be achieved by combining two independent CAT 2 protection concepts or by certain types of intrinsically safe or specially encapsulated circuits (assuming other requirements such as non electrical and static can be met) or by (for example) having an Ex e Motor within and Ex d enclosure
IP
Ingress Protection
Degree of protection from foreign bodies (from test fingers to dust) and water (from rain to sprayed jets)
LEL
LFL
Lower Explosive/Flammable Limit at which a substance will ignite
Substance  LEL(%)
Methane      4.4
Propane       1.7
Ethylene      2.3
Acetylene     2.3
Hydrogen     4
See FlamCal for full LEL data for most flammable gas types
UEL
UFL
Upper Explosive/Flammable Limit at which a substance will ignite
Substance   UEL(%)
Methane       17
Propane        11
Ethylene       36
Acetylene     100
Hydrogen      77
 See FlamCal for full UEL data for most flammable gas types
Temperature Class ATEX, AEx and IEC Equipment is identified with a temperature class. It is either identified by a ‘T’ rating or by a temperature in degrees C. The temperature class identifies the hottest temperature that the equipment can obtain. This can be either the inside or the outside of the equipment depending on the protection concept.
Temperature Class    Max Temp limit(C)
T1                              450
T2                              300
T3                              200
T4                              135
T5                              100
T6                              85