| Glossary Word | Description |
| ATEX 95 | (ATmosphere EXplosive): Mandatory Legislation from July 1st 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 of 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 |
| 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. |
| 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. |
| SoR | Source of Release (for Area Classification- the leak path that may lead to a zone) |
| SoH | Source of Hazard (for Area Classification- the leak path that may lead to a zone) |
| LEL LFL | Lower Explosive/Flammable Limit at which a substance will ignite Example Substance | LEL (%) | UEL (%) | Methane | 4.4 | 17 | Propane | 1.7 | 11 | Ethylene | 2.3 | 36 | Acetylene | 2.3 | 100 | Hydrogen | 4 | 77 |
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| UEL UFL | Lower Explosive/Flammable Limit at which a substance will ignite Example Substance | LEL (%) | UEL (%) | Methane | 4.4 | 17 | Propane | 1.7 | 11 | Ethylene | 2.3 | 36 | Acetylene | 2.3 | 100 | Hydrogen | 4 | 77 |
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| Flashpoint | The temperature at which a liquid will form a flammable atmosphere |
| 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. |
| 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. |
| 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 which 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 marking 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. |
| 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, where 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 marking 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, and a fault capable of causing ignition is not likely to occur. Equipment designed to this concept is suitable for use in ‘Zone 2’ classified hazardous areas. Breaks down to several concepts, nL, nA, nC, nP, nR. |
| nL | Not enough energy in an electrical circuit to be an effective ignition |
| nA | Non-sparking for zone 2 |
| nC | Various methods of preventing ignition form zone 2 including enclosed break. |
| nP | Zone 2 purge |
| nR | Restricted breathing protection concept Zone 2) |
| 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. |
| Encapsulation EEx m Ex m | 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 1’ and ‘Zone 2’ classified hazardous areas. |
| IP Ingress Protection | Degree of protection from foreign bodies (from test fingers to dust) and water (from rain to sprayed jets) Click here for a chart of ingress protection |
| MEIC | At a critical concentration called the most easily ignited concentration (MEIC), the amount of energy required to cause ignition is minimal. |
| Detonation | Detonation: A violent explosion, flame front speed 200-3000 m/sec, speed of sound 330 m/sec |
| Temperature Class T1 T2 T3 T4 T5 T6 | 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 a 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 |
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| AEx | American Explosion proof (NEC505) |
| EEx | European Explosion proof |
| Ex | Explosion proof |
| Zone 0 | A location where an explosive atmosphere consisting of a mixture of with air or flammable substances in the form of a gas, vapour or mist is present continuously or for long periods. |
| Zone 1 | A location where an explosive atmosphere consisting of a mixture of with 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 with air or flammable substances in the form of a gas, vapour or mist is not likely to occur in normal operation occasionally but if it does will occur will only persist for a short period only. |
| Zone 20 | A location where an explosive atmosphere consisting of a mixture of with air or 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 with air or 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 with air or flammable substances in the form of dust is not likely to occur in normal operation occasionally but if it does will occur will only persist for a short period only. |
| IP15 | Institute of Petroleum Model code of Safe Practice Part 15 (Petroleum Products) |
| Risk Assessment | Determining by systematic examination the overall system risk by evaluating the frequency and consequences of hazards. |
| LVD | Low Voltage Directive – A European CE Directive concerned with he safety (primarily electrical) of products with a supply voltage over 50V AC, 75V DC. |
| EMC | Electromagnetic Compatibility– A European CE Directive concerned with he safety of products with reference to Radio Frequencies, magnetic interference and supply interference. Products must pass both ‘emissions’ (what they give out) and ‘immunity’ (what they are capable of receiving whilst still operating). |
| PED | Pressure Equipment Directive– A European CE Directive concerned with he safety of products from overpressure. The starting pressure for this Directive is 0.5 bar. |
| Machinery Directive | The Machinery Directive is a European CE Directive concerned with he mechanical and electrical safety of machines (where the mechanical risk is greater than the electrical risk- if the electrical risk is greater, use the Low Voltage Directive). The Machinery Directive is largely based on Risk Assessment and use of EU Standards for critical features such as guards and emergency stops. |
| 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. |
| Notified Body | A body such as Epsilon Compliance 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. |
