CEN/TC 305 - Potentially explosive atmospheres - Explosion prevention and protection

This document specifies the requirements for flame arresters that prevent flame transmission when explosive gas-air or vapour-air mixtures are present. It establishes uniform principles for the classification, basic construction and information for use, including the marking of flame arresters, and specifies test methods to verify the safety requirements and determine safe limits of use. This document is applicable to pressures ranging from 80 kPa to 160 kPa and temperatures ranging from -20 °C to +200 °C. This document does not apply to the following: - external safety-related measurement and control equipment that might be required to keep the operational conditions within the established safe limits; - flame arresters used for explosive mixtures of vapours and gases, which tend to self-decompose (for example, acetylene) or which are chemically unstable; - flame arresters used for carbon disulfide, due to its special properties; - flame arresters whose intended use is for mixtures other than gas-air or vapour-air mixtures (for example, higher oxygen-nitrogen ratio, chlorine as oxidant); - flame arrester test procedures for reciprocating internal combustion engines; - fast acting valves, extinguishing systems and other explosion isolating systems; - Flame arresters used in gas detectors (those being covered for example, by IEC 60079‑29‑1 and IEC 62990‑1). This edition cancels and replaces ISO 16852:2016, which has been technically revised. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to ISO 16852:2016: a) adaptation of the relevant IEC TC 31 requirements on standards; b) modification of the upper limit of the temperature range from 150 °C to 200 °C under the condition that T0 shall be not larger than 80 % of the auto ignition temperature of the gas-air-mixture; c) change of the term "explosion group" to "equipment group" due to editorial requirements in IEC/TC 31; d) clarification of the conditions and requirements for flame arresters whose intended operating conditions are outside the atmospheric conditions in 7.3.4 and 7.3.5; e) clarification of the requirements on the information for use in Clause 12 f) concerning the burn time; f) addition of a permission to the construction requirements both in 7.1 and 14.1 to substitute visual inspection by performing a flow test; g) addition of a flow chart for the evaluation of test results as Annex D

This document specifies the requirements for equipment and protective systems for firedamp drainage at mines. It also contains requirements for the construction and monitoring of this equipment and protective systems (see EN 1127 2:2014).
This document does not apply to firedamp utilization systems beyond the utilization shut-off device.

This document specifies terms and definitions (vocabulary) to be used in suitable standards dealing with equipment and protective systems intended for use in potentially explosive atmospheres within the scope of Directive 2014/34/EU.
NOTE   Terms and definitions avoid misunderstandings that are important in relation to the essential health and safety requirements of Directive 2014/34/EU.

1.1   This document specifies the constructional requirements for fans constructed to Group II G (of explosion groups IIA, IIB and hydrogen) categories 1, 2 and 3, and Group II D categories 2 and 3, intended for use in explosive atmospheres.
NOTE 1   Operation conditions for the different categories of fans used in this document are defined in Clause 4.
1.3   This document specifies requirements for design, construction, testing and marking of complete fan units intended for use in potentially explosive atmospheres in air containing gas, vapour, mist and/or dusts. Such atmospheres can exist inside (the conveyed atmosphere (flammable or not)), outside, or inside and outside of the fan.
This document covers mechanical equipment, in particular fans. The “type of protection” as specified in EN ISO 80079 37:2016 is constructional safety.
1.4   This document is applicable to fans working in ambient atmospheres and with normal atmospheric conditions at the inlet, having
—   absolute pressures ranging from 0,8 bar to 1,1 bar,
—   and temperatures ranging from −20 °C to +60 °C,
—   and maximum volume fraction of 21 % oxygen content,
—   and an aerodynamic energy increase of less than 25 kJ/kg.
NOTE 1   25 kJ/kg is equivalent to 30 kPa at inlet density of 1,2 kg/m3.
This document can also be helpful for the design, construction, testing and marking of fans intended for use in atmospheres outside the validity range stated above or in cases where other material pairings need to be used. In this case, the ignition risk assessment, ignition protection provided, additional testing (if necessary), manufacturer's marking, technical documentation and instructions to the user, clearly demonstrate and indicate the equipment's suitability for the conditions the fan can encounter.
NOTE 2   Temperatures below −20 °C can be considered. Material suitability can require specific evaluation for these temperatures. With lower temperature the explosion pressure increases, which leads to increased test pressures (see A.3) and can require specific testing. Although the standard atmospheric conditions in EN ISO 80079 36:2016 give a temperature range for the atmosphere of −20 °C to +60 °C the normal ambient temperature range for the equipment is −20 °C to +40 °C unless otherwise specified and marked.
1.5   This document does not apply to:
—   group I fans (fans for mining);
—   explosion group IIC (other than hydrogen);
—   category 1D fans;
—   cooling fans or impellers on rotating electrical machines;
—   cooling fans or impellers on internal combustion engines, vehicles or electric motors.
NOTE 3   Measures for category 1D fans are given in EN 1127 1:2019.
NOTE 4   Measures for explosion group IIC (other than hydrogen) are given in EN 1127 1:2019.
NOTE 5   Measures for explosion group I are given in EN ISO/IEC 80079 38:2016 and EN 1127 2:2014.

This document specifies requirements for design, construction, testing and marking of hand-held, portable and transportable vacuum cleaners, including their accessories, constructed to Group II, categories 2G or 3G (of explosion groups IIA, IIB, IIB plus hydrogen), and to Group II, categories 2D or 3D (of explosion groups IIIA, IIIB and IIIC), intended for the collection of combustible or non-combustible dusts and flammable or non-flammable liquids in potentially explosive atmospheres. A potentially explosive atmosphere could be generated by the equipment during its intended use.
NOTE 1   The accumulation of 1 mm or more of combustible dust on surfaces in a working area can create an explosive atmosphere (see reference to 1/32 in. of Depth of Dust Accumulation for Guidance for Area Electrical Classification in NFPA 654, 2017 Edition).
This document applies to equipment driven by electric power and by pneumatic power.
This document gives guidelines for dealing with significant hazards, hazardous situations and/or events relevant to vacuum cleaners when they are used as intended and under conditions of misuse which are reasonably foreseeable by the manufacturer.
Typical applications for the concerned equipment are:
-   collection of dust produced by machinery at the point of generation;
-   general housekeeping around machinery and of working areas; and/or
-   collection of spills;
-   cleaning of equipment during maintenance operations; and/or
-   collection of specific waste.
For the collection of dust in the presence of flammable liquids or vapours, a specific risk assessment is performed if this is part of the vacuum cleaners intended conditions of use and additional precautions beyond what is described in this document can be required.
NOTE 2   The passage of dust through a vacuum cleaner will generate high levels of electrostatic charge which, in most situations, will be a potential source of ignition to a flammable gas or vapour atmosphere.
For the collection of low-conductivity flammable liquids, a specific risk assessment is performed if this is part of the vacuum cleaners intended conditions of use and additional precautions beyond what is described in this document can be required.
NOTE 3   The resulting liquid velocities are likely to be in excess of the limits required to maintain electrostatic charge generation at a non-hazardous level according to CLC/TR 60079 32 1:2018.
This document does not apply to equipment used to collect toxic dusts where there is a health risk if dust passes through the filter elements. This document does not apply to the collection of dusts which have explosive and unstable properties (UN transport class 1, class 4.1 and class 5.2).
NOTE 4   Hazards related to the use of vacuum cleaners for the collection of hazardous dusts are the subject of other standards.
This document applies to vacuum cleaners with an internal dirty air volume of maximum 250 l.
NOTE 5   250 l is the volume above which it is recognized a vacuum cleaner might not be considered as transportable by an operator, and above which additional explosion protections can be required.
The present version of the document does not apply to battery operated equipment.
NOTE 6   Battery operated equipment might be part of the scope of this document in a subsequent version.
This document does not apply to vacuum trucks.
This document applies to vacuum cleaners of canister and back-pack types. This document does not apply to upright vacuum cleaners.
This document does not apply to motorized cleaning head accessories.
NOTE 7   This document does not apply to household appliances which are the subject of other standards.
This document does not apply to applications where the substances are conveyed into a separate receiving container.
This document does not apply to equipment intended for use in underground parts of mines as well as those parts of surface installations of such mines endangered by firedamp and/or combustible dust.
..

This document describes the basic requirements for the design and application of explosion suppression systems. This document also specifies test methods for evaluating the effectiveness and the scaling up of explosion suppression systems against defined explosions. This document covers:
-   general requirements for explosion suppression system parts;
-   evaluating the effectiveness of an explosion suppression system;
-   evaluating the scale up of an explosion suppression system to larger than tested volumes;
-   development and evaluation of design tools for explosion suppression systems;
-   installation, operation and maintenance instructions for an explosion suppression system.
This document is applicable only to explosion suppression systems intended for the protection of closed, or essentially closed, enclosures in which an explosion could result as a consequence of ignition of an explosible mixture, e.g. dust-air, gas(vapour)-air, dust-gas(vapour)-air and mist-air.
This document is not applicable for explosions of materials listed below, or for mixtures containing some of those materials:
-   unstable materials that are liable to dissociate;
-   explosive materials;
-   pyrotechnic materials;
-   pyrophoric materials.

Inerting is a preventive measure to avoid explosions or fire to happen. By feeding inert gas into a system, which is to be protected against an explosion or a fire, the oxygen content is reduced below a certain limit or completely replaced by an inert gas, depending on the inert gas, on the fuel and the process until no explosion or fire can occur or develop.
Inerting can be used to prevent fire and explosion by reducing the O2 content.
NOTE Inerting can also be used to prevent and to extinguish smouldering nests and glowing fires which are a primary source of ignition in pulverized fuel storage and handling facilities, substituting air by sufficient inert gas inside the equipment.
The following cases are not covered by the guideline:
- admixture of an inert solid powder to a combustible dust;
- inerting of flammable atmospheres by wire mesh flame traps in open spaces of vessels and tanks;
- firefighting;
- avoiding an explosive atmosphere by exceeding the upper explosion limit of a flammable substance;
- anything related to product quality (oxidation or ingress of humidity) or product losses;
- any explosive atmosphere caused by other oxidizing agents than oxygen.
Other technologies might be used in combination with inerting such as floating screens made of independent collaborative floaters consisting of an array of small floaters non-mechanically linked but overlapping each other in order to form a continuous layer covering the liquid surface.
Product oxidation or evaporation reduction is directly proportional to the surface area covering ratio and quality of the inerting.

This document specifies a test method to determine the explosion limits of gases, vapours and their mixtures, mixed with a gaseous oxidizer or an oxidizer/inert gas mixture at pressures from 0,10 MPa to 10 MPa and for temperatures up to 400 °C.

This document specifies a test method that is designed to measure the explosion pressure and the maximum explosion pressure, the rate of explosion pressure rise and the maximum rate of explosion pressure rise of a quiescent flammable gas/air/inert mixture in closed volume at ambient temperature and pressure. In this document, the term “gas” includes vapours but not mists. Detonation and decomposition phenomena are not considered in this document.
The pressures and rates of pressure rise measured by the procedures specified in this document are not applicable to flameproof enclosures, i.e. enclosures intended to withstand an internal explosion and not to transmit it to an external explosive atmosphere, or any other closed volume where the internal geometry can result in pressure piling. Even in an enclosure of relatively simple geometry the disposition of the internal components can lead to rates of pressure rise significantly higher than those measured using this document. This document does not apply to the design and testing of flameproof enclosures in conformity with EN ISO 80079-37 (for non-electrical equipment) and EN 60079-1 (for electrical equipment).

This document describes the recommendations for the design and use of screw conveyors and product receivers which can in addition be used as a means for explosion isolation to prevent a dust explosion transmission into connected plant items by using the bulk material which is inside.
The recommendations given in this document are procedural measures since the properties of the bulk material affect the efficacy of this measure essentially (e.g. flow and explosion characteristics). Product receivers and screw conveyors cannot be considered as protective systems under the scope of the ATEX Directive.
As far as screw conveyors are concerned, the scope of this document is limited to rigid, tubular, singular screw conveyors which consist of a spiral blade coiled around a shaft held by external bearings (the rotating part of the conveyor is sometimes called “auger”).
NOTE   Additional internal bearings can be necessary if the tubular screw conveyor exceeds a certain length.
This document includes limits of application where a plug of bulk material in a screw conveyor is not possible/sufficient to achieve explosion isolation and also application ranges where a plug of bulk material is not necessary to achieve explosion isolation.
This document does not address the mandatory risk analysis and ignition hazard assessment, which are performed for the application of the screw conveyors and product receivers. The mandatory risk assessment includes start-up and shut-down conditions, when potentially no plug of material is present to prevent explosion propagation. To mitigate this residual risk, it is possible to use as an extra measure, e.g. a traditional gate valve which prevents flame transmission and is able to withstand the expected maximum explosion pressure.

ISO/IEC 80079-20-1:2017 is published as a dual log standard and provides guidance on classification of gases and vapours. It describes a test method intended for the measurement of the maximum experimental safe gaps (MESG) for gas-air mixtures or vapour-air mixtures under normal conditions of temperature and pressure (20 °C, 101,3 kPa) so as to permit the selection of an appropriate group of equipment. This document also describes a test method intended for use in the determination of the auto-ignition temperature (AIT) of a vapour-air mixture or gas-air mixture at atmospheric pressure, so as to permit the selection of an appropriate temperature class of equipment. Values of chemical properties of materials are provided to assist in the selection of equipment to be used in hazardous areas. Further data may be added as the results of validated tests become available. The materials and the characteristics included in a table (see Annex B) have been selected with particular reference to the use of equipment in hazardous areas. The data in this document have been taken from a number of references which are given in the bibliography. These methods for determining the MESG or the AIT may also be used for gas-air-inert mixtures or vapour-air-inert mixtures. However, data on air-inert mixtures are not tabulated.
Keywords: classification of gases and vapours, measurement of the maximum experimental safe gaps (MESG)

This document specifies methods for the identification and assessment of hazardous situations leading to explosion and the design and construction measures appropriate for the required safety. This is achieved by:
-   risk assessment;
-   risk reduction.
The safety of equipment, protective systems and components can be achieved by eliminating hazards and/or limiting the risk, i.e. by:
a)   appropriate design (without using safeguarding);
b)   safeguarding;
c)   information for use;
d)   any other preventive measures.
Measures in accordance with a) (prevention) and b) (protection) against explosions are dealt with in Clause 6, measures according to c) against explosions are dealt with in Clause 7. Measures in accordance with d) are not specified in this document. They are dealt with in EN ISO 12100:2010, Clause 6.
The preventive and protective measures described in this document will not provide the required level of safety unless the equipment, protective systems and components are operated within their intended use and are installed and maintained according to the relevant codes of practice or requirements.
This document specifies general design and construction methods to help designers and manufacturers in achieving explosion safety in the design of equipment, protective systems and components.
This document is applicable to any equipment, protective systems and components intended to be used in potentially explosive atmospheres, under atmospheric conditions. These atmospheres can arise from flammable/combustible substances processed, used or released by the equipment, protective systems and components or from materials in the vicinity of the equipment, protective systems and components and/or from the materials of construction of the equipment, protective systems and components.
This document is applicable to equipment, protective systems and components at all stages of its use.
This document is only applicable to equipment group II which is intended for use in other places than underground parts of mines and those parts of surface installations of such mines endangered by firedamp and/or combustible dust.
This document is not applicable to:
1)   medical devices intended for use in a medical environment;
2)   equipment, protective systems and components where the explosion hazard results exclusively from the presence of explosive substances or unstable chemical substances;
3)   equipment, protective systems and components where the explosion can occur by reaction of substances with other oxidizers than atmospheric oxygen or by other hazardous reactions or by other than atmospheric conditions;
4)   equipment intended for use in domestic and non-commercial environments where potentially explosive atmospheres may only rarely be created, solely as a result of the accidental leakage of fuel gas;
5)   personal protective equipment covered by Regulation (EU) 2016/425;
6)   seagoing vessels and mobile offshore units together with equipment on board such vessels or units;
7)   means of transport, i.e. vehicles and their trailers intended solely for transporting passengers by air or by road, rail or water networks, as well as means of transport insofar as such means are designed for transporting goods by air, by public road or rail networks or by water; vehicles intended for use in a potentially explosive atmosphere shall not be excluded;
8)   the design and construction of systems containing desired, controlled combustion processes, unless they can act as ignition sources in potentially explosive atmospheres.

This European Standard specifies analysis and evaluation procedures for determining self-ignition temperatures (TSI) of combustible dusts or granular materials as a function of volume by hot storage experiments in ovens of constant temperature. The specified test method is applicable to any solid material for which the linear correlation of lg (V/A) versus the reciprocal self-ignition temperature 1/TSI (with TSI in K) holds (i.e. not limited to only oxidatively unstable materials).
This European Standard is not applicable to the ignition of dust layers or bulk solids under aerated conditions (e.g. as in fluid bed dryer).
This European Standard shall not be applied to dusts like recognised explosives that do not require atmospheric oxygen for combustion, nor to pyrophoric materials.
NOTE   Because of regulatory and safety reasons "recognised explosives" are not in the scope of this European Standard. In spite of that, substances which undergo thermal decomposition reactions and which are not "recognised explosives" but behave very similarly to self-ignition processes when they decompose are in the scope. If there are any doubts as to whether the dust is an explosive or not, experts should be consulted.

ISO/IEC 80079-34:2018 specifies particular requirements and information for establishing and maintaining a quality management system to manufacture Ex Products in accordance with the certificates. While it does not preclude the use of other quality management systems that are compatible with the objectives of ISO 9001:2015 and which provide equivalent results, the minimum requirements are given in this document.
This second edition cancels and replaces the first edition, published in 2011, and constitutes a full technical revision. The significant changes with respect to the previous edition should be considered as minor technical revisions. However, the clause numbering in regard to the previous edition has changed in order to be in line with ISO 9001:2015. The normal “Table of Significant Changes” has not been included for this reason.
This publication is published as a double logo standard. This standard should be read in conjunction with ISO 9001:2015

2021-03-25 CV: rejected for OJEU citation but corrigenda are out of EY scope

ISO 80079-37:2016 specifies the requirements for the design and construction of non-electrical equipment, intended for use in explosive atmospheres, protected by the types of protection        
constructional safety "c", control of ignition source "b" and liquid immersion "k". This part of ISO/IEC 80079 supplements and modifies the requirements in ISO 80079-36. Where a requirement of this standard conflicts with the requirement of ISO 80079-36 the requirement of this standard takes precedence. Types of protection "c", "k" and "b" are not applicable for Group I, EPL Ma without    
additional protective precautions. The types of ignition protection described in the standard can be used either on their own or in combination with each other to meet the requirements for equipment of Group I, Group II, and Group III depending on the ignition hazard assessment in ISO 80079-36.                                        
Keywords: constructional safety "c", control of ignition source "b" and liquid immersion "k"

ISO 80079-36:2016 specifies the basic method and requirements for design, construction, testing and marking of non-electrical Ex equipment, Ex Components, protective systems, devices and assemblies
of these products that have their own potential ignition sources and are intended for use in explosive atmospheres. Hand tools and manually operated equipment without energy storage are excluded from the scope of this standard. This standard does not address the safety of static autonomous process equipment when it is not part of equipment referred to in this standard. This standard does not specify requirements for safety, other than those directly related to the risk of ignition which may then lead to an explosion. The standard atmospheric conditions (relating to the explosion    characteristics of the atmosphere) under which it may be assumed that equipment can be operated are:
- temperature -20 °C to 60 °C;
- pressure 80 kPa (0,8 bar) to 110 kPa (1,1 bar); and
- air with normal oxygen content, typically 21 % v/v. Such atmospheres can also exist inside the equipment. In addition, the external atmosphere can be drawn inside the equipment by natural breathing produced as a result of fluctuations in the equipment's internal operating pressure, and/or temperature. This part of ISO/IEC 80079 specifies the requirements for the design and      
construction of equipment, intended for explosive atmospheres in conformity with all Equipment Protection Levels (EPLs) of Group I, II and III. This standard supplements and modifies the general    
requirements of IEC 60079-0, as shown in Table 1 in the Scope of the document.                                                          
Keywords: mechanical explosion protected equipment

This European Technical Report applies to bucket elevators that may handle combustible products capable of producing potentially explosive atmospheres of dust or powder inside the bucket elevator during its operation. The precautions to control ignition sources will also be relevant where the product in the bucket elevator creates a fire risk but not an explosion risk.
For the purposes of this report, a bucket elevator is defined as an item of bulk material handling equipment that carries material in powder form or as coarse products such as whole grain, wood chips or flakes, in a vertical direction by means of a continuous movement of open containers.
This Technical Report specifies the principles of and guidance for fire and explosion prevention and explosion protection for bucket elevators.
Prevention is based on the avoidance of effective ignition sources, either by the elimination of ignition sources or the detection of ignition sources.
Explosion protection is based on the application of explosion venting, explosion suppression or explosion containment and explosion isolation rules specifically adapted for bucket elevators. These specific rules may be based on agreed test methods.
This European Technical Report does not apply to products that do not require atmospheric oxygen for combustion.

2018-05-03 CV: CEN BT C218/2017 - decision: new Annex ZA to be published as amendment prior to offer EN ISO/IEC 80079-39:2016 + amd for citation in the OJEU

This European Standard describes a test method for the determination of the burning behaviour of dust layers under defined initial conditions of air flow, temperature and ignition.
A test result of burning class 1 with the described method does not mean that a dust cannot be ignited when dispersed in a cloud.
This method is not suitable for use with recognized explosives, like gunpowder and dynamite, explosives which do not require atmospheric oxygen for combustion, pyrophoric substances, or substances or mixtures of substances which may under some circumstances behave in a similar manner. Expert advice should be called in, when any doubt exists about the existence of hazard due to explosive properties.

This European Standard specifies requirements for explosion resistant equipment which will be able to withstand an internal explosion without rupturing and will not give rise to dangerous effects to the surroundings. It is applicable to equipment (vessels and systems) where explosions are considered to be an exceptional load case.
There are two types of explosion resistant equipment: explosion pressure resistant and explosion pressure shock-resistant equipment (see Figure 1).
(...)
Explosion pressure resistant equipment is designed to withstand the explosion pressure without permanent deformation and will not give rise to dangerous effects to the surroundings. Since the design and calculation methods for explosion pressure resistant equipment are similar to those described in EN 13445-1 to -6 "Unfired pressure vessels" they are not repeated in this standard.
For explosion pressure shock resistant equipment permanent deformation is allowed provided the equipment will not give rise to dangerous effects to the surroundings. This design has been developed especially for explosion protection purposes. This standard focusses on the requirements for explosion pressure shock resistant equipment.
This standard is valid for atmospheres having absolute pressures ranging from 800 mbar to 1 100 mbar and temperatures ranging from −20 °C to +60 °C. This standard may also be helpful for the design, construction, testing and marking of equipment intended for use in atmospheres outside the validity range stated above, as far as this subject is not covered by specific standards.
This standard applies to equipment and combinations of equipment where deflagrations may occur and is not applicable to equipment and combination of equipment where detonations may occur. In this case, different design criteria for the required explosion resistance are applicable which are not covered by this standard.
It is not applicable to equipment which is designed according to type of protection, flameproof enclosures "d" (EN 13463-3 or EN 60079-1).
This standard does not apply to offshore situations.
This standard is only applicable for equipment where metallic materials provide the explosion resistance. This standard does not cover fire risk associated with the explosions, neither with the materials processed nor with the materials used for construction.

This European Standard specifies two test methods (method T and method B) to determine the explosion limits of gases, vapours and their mixtures, mixed with air. An air/inert gas mixture (volume fraction of the oxygen < 21 %) can be used as the oxidizer instead of air. In this European Standard, the term "air" includes such air/inert mixtures. This European Standard applies to gases, vapours and their mixtures at atmospheric pressure for temperatures up to 200 °C.
This European Standard specifies in addition the method for determining the LOC of mixtures consisting of flammable gas or vapour, air and inert gas at atmospheric pressure and temperatures from ambient temperature to 200 °C.
NOTE: This method was previously specified in EN 14756.

2017-07-03 - Endorsement of ISO corrigendum including corrigendum content for the EN ISO version! TAN & SV collaboration

ISO/IEC 80079-38:2016 is published as a dual logo standard and specifies the explosion protection requirements for the design, construction, assessment and information for use (maintenance, repair, marking) of equipment that may be an individual item or form an assembly. This includes machinery and components for use in mines susceptible to explosive atmospheres of firedamp and/or combustible
dust. The standard atmospheric conditions (relating to the explosion characteristics of the atmosphere) under which it may be assumed that equipment can be operated are:
- temperature -20 °C to 60 °C;
- pressure 80 kPa (0,8 bar) to 110 kPa (1,1 bar);
- and air with normal oxygen content, typically 21 % v/v. This part of ISO/IEC 80079 applies for equipment and components according to EPL Mb to be used in explosive atmospheres containing firedamp and/or combustible dust. For equipment and components according to EPL Ma, the requirements of this standard and of ISO 80079-36 and IEC 60079-0 apply. It is necessary to take account of external  
conditions to the equipment which may affect the hazard and the resultant protection measures. These measures may include ventilation, gas detection or gas drainage. This part of ISO/IEC 80079 also deals with the prevention of ignitions of explosive atmospheres caused by burning (or smouldering) of combustible material such as fabric fibres, plastic "O"-rings, rubber seals, lubricating oils or greases used in the construction of the equipment if such items could be an ignition source. For example, the mechanical failure of rotating shaft bearings can result in frictional heating that ignites its plastic cage, plastic seal or lubricating grease. Detailed requirements and test procedures for the fire protection of conveyer belts are not part of this part of ISO/IEC 80079.         Keywords: explosive atmospheres in underground mines, combustible dust

ISO/IEC 80079-20-2:2016 is published as a dual logo standard and describes the test methods for the identification of combustible dust and combustible dust layers in order to permit classification
of areas where such materials exist for the purpose of the proper selection and installation of electrical and mechanical equipment for use in the presence of combustible dust. The standard    
atmospheric conditions for determination of characteristics of combustible dusts are:
- temperature -20 °C to 60 °C,
- pressure 80 kPa (0,8 bar) to 110 kPa (1,1 bar) and
- air with normal oxygen content, typically 21 % v/v. The test methods defined do not apply to:
- recognized explosives, propellants (e.g. gunpowder, dynamite), or substances or mixtures of substances which may, under some circumstances, behave in a similar manner or
- dusts of explosives and propellants that do not require atmospheric oxygen for combustion, or to pyrophoric substances. This first edition cancels and replaces the first edition of IEC 61241-2-1 published in 1994, the first edition of IEC 61241-2-2 published in 1993 and the first edition of IEC 61241-2-3 published in 1994, combining the requirements into a single document, and is considered to constitute a technical revision. Significant changes with respect to IEC 61241-2-1:1994, IEC 61241-2-2:1993 and IEC 61241-2-3:1994 can be found in the foreword of the document.      
Keywords: combustible dust

This Technical Report is aimed primarily at persons who are responsible for the safe design and operation of installations and equipment using flammable liquids, vapours or gases.
This document applies to both industrial and mining applications
This document describes possible risks and gives proposals for the protection against these risks by the use of flame arresters.
This document gives some guidance to choice of flame arresters according to EN ISO 16852 for different common scenarios and it gives best practice for the installation and maintenance of these flame arresters.

This European Standard describes the general requirements for flap valves used for dust explosion isolation. An explosion isolation flap valve is a protective system, which prevents a dust explosion from propagating via connecting pipes or ducts into other parts of apparatus or plant areas.
An explosion isolation flap valve can only stop the propagation of a dust explosion when it propagates against the direction of the normal process flow. It does not stop explosions running in the normal process flow direction. This European Standard specifies methods for evaluating the efficacy of explosion isolation flap valves.
This European Standard is applicable only to the use of explosion isolation flap valves that are intended for avoiding explosion propagation from a vessel, into other parts of the installation via connecting pipes or ducts. The standard covers isolation of such vessels that are protected by explosion venting (including flameless venting), explosion suppression or explosion resistant design.
NOTE 1   The standard assumes that the explosion starts in a vessel and not in ducting.
Explosion isolation flap valves are not designed to prevent the transmission of fire or burning powder transported by the normal process flow.
NOTE 2   It is necessary to take this into account in risk assessments.
This European Standard is only applicable for dust explosions.
This European Standard is not applicable for explosions of materials listed below, or for mixtures containing some of those materials:
a)   gases, vapours and hybrid mixtures;
b)   chemically unstable substances;
c)   explosive substances;
d)   pyrotechnic substances.

This European Standard specifies methods for explosion prevention and protection in mining by outlining the basic concepts and methodology for the design and construction of equipment, protective systems and components.
This European Standard applies to Group I equipment, protective systems and components intended for use in underground parts of mines and those parts of their surface installations at risk from firedamp and/or flammable dust.
NOTE   Detailed information on specific equipment, protective systems and components is contained in the relevant individual standards. Safety-relevant data regarding flammable materials and explosive atmospheres are required for the design and construction of the explosion protection measures.
This European Standard specifies methods for the identification and assessment of hazardous situations that may lead to explosions and describes the design and construction measures appropriate for the required safety. This is achieved by
-   risk assessment;
-   risk reduction.
The safety of equipment, protective systems, and components can be achieved by eliminating hazards and/or limiting the risk, i.e.
a)   by appropriate design (without using safeguarding);
b)   by safeguarding;
c)   by information for use;
d)   by any other preventive measures.
Measures in accordance with a) (prevention) and b) (protection) against explosions are dealt with in clause 6 of this standard, measures according to c) against explosions are dealt with in clause 7 of this standard. Mea¬sures in accordance with d) are not described in this European Standard. They are dealt with in EN ISO 12100:2010, clause 6.
The preventive and protective measures described in this European Standard will not provide the required level of safety unless the equipment, protective systems and components are operated in line with their intended use and are installed and maintained according to the relevant codes of practice or requirements.
This standard is applicable to any equipment, protective systems and components intended to be used in potentially explosive atmospheres. These atmospheres can arise from flammable materials processed, used or released by the equipment, protective systems and components or from materials in the vicinity of the equipment, protective systems and components and/or from the materials of construction of the equipment, protective systems and components.
As shot firing can release potentially explosive atmospheres, this standard is also applicable to the equipment used for shot firing, apart from the explosives and detonators.
This standard is applicable to equipment, protective systems and components at all stages of use.
This standard is not applicable to:
-   medical devices intended for use in a medical environment;
-   equipment, protective systems and components where the explosion hazard results exclusively from the presence of explosives or unstable chemical substances;
-   equipment, protective systems and components where the explosion can result from reaction of substances with oxidising agents other than atmospheric oxygen or by other hazardous reactions or conditions other than atmospheric conditions;
-   equipment intended for use in domestic and non-commercial environments where explosive atmospheres may only rarely be created and solely as a result of the accidental leakage of fuel gas;
-   personal protective equipment covered by Directive 89/686/EEC; the design and construction of systems containing desired, controlled combustion processes, unless they can act as ignition sources in potentially explosive atmospheres;
-   mines where firedamp and/or flammable dust are not naturally present and surface installations such as coal preparation plants, power plants, coke oven plants etc. in which an explosive atmosphere can be present, but which are not part of a coal mine. These are covered by EN 1127-1:2011.

This European Standard specifies the basic requirements of design for the selection of a dust explosion venting protective system. The standard is one of a series including EN 14797, Explosion venting devices and EN 14460, Explosion resistant equipment. The three standards together represent the concept of dust explosion venting. To avoid transfer of explosions to other communicating equipment, one should also consider applying EN 15089 Explosion Isolation Systems.
This European Standard covers:
-   vent sizing to protect an enclosure against the internal pressure effects of a dust explosion;
-   flame and pressure effects outside the enclosure;
-   recoil forces;
-   influence of vent ducts;
-   hybrid mixtures.
This European Standard is not intended to provide design and application rules against effects generated by detonation reactions or runaway exothermic reactions. This European Standard does not cover fire risks arising from materials either processed, used or released by the equipment or from materials that make up equipment and buildings. This European Standard does not cover the design, construction, testing and certification of explosion venting devices that are used to achieve explosion venting

An explosion diverter is used to divert explosions propagating through ducts, thus preventing flame jet ignition and pressure piling in connected protected enclosures. It will reduce the risk of flame transmission.
This European Standard describes the basic design of a pipe-in-pipe diverter and specifies the testing requirements and the application of explosion diverters.
This European Standard covers:
- a test method for assessing the efficacy of explosion diverters;
- design rules for a type of pipe-in-pipe diverter;
- demands to venting device on diverter;
- installation requirements;
- maintenance requirements;
- marking.
This European Standard considers dust/air explosive atmospheres only.

This European Standard specifies the requirements for flameless explosion venting devices used to protect enclosures against the major effects of internal explosions arising from the rapid burning of suspended dust, vapour or gas contained within. It includes the requirements for the design, inspection, testing, marking, documentation, and packaging. This standard is applicable to flameless explosion venting devices which are put on the market as autonomous protective systems.
Explosion venting devices are protective systems comprised of a pressure sensitive membrane fixed to and forming part of the structure that it protects. They are designed to intervene in the event of an explosion at a predetermined pressure, to immediately open a vent area sufficient to ensure that the maximum pressure attained by an explosion within the enclosure does not exceed the maximum pressure the structure is designed to withstand.
Flameless explosion venting devices typically consist of an explosion venting device in combination with a flame quenching element to avoid the transmission of flames into the surroundings. They are used to allow explosion venting in situations where otherwise the hazards of flames and pressure resulting from the venting would harm personnel or damage structures.
The application and specification of explosion venting devices is outlined for dust explosion protection in EN 14491 and for gas explosion protection in EN 14994.
This standard covers the flameless explosion venting of dust, vapour and gas explosions.
This standard does not cover details for the avoidance of ignition sources from detection devices or other parts of the flameless explosion venting devices.

This document describes a test method for the determination of the limiting oxygen concentration of dust clouds in a closed vessel under defined initial conditions of pressure and temperature.
This method is not suitable for use with recognised explosives, like gunpowder and dynamite, substances which do not require oxygen for combustion, pyrophoric substances, or substances or mixtures of substances which may under some circumstances behave in a similar manner. Where any doubt exists about the existence of hazard due to explosive properties, expert advice should be sought.

This standard describes a test method for the determination of the lower explosion limit of dust clouds in a closed vessel under defined initial conditions of pressure and temperature.
This method is not suitable for use with recognised explosives, like gunpowder and dynamite, explosives which do not require oxygen for combustion, pyrophoric substances, or substances or mixtures of substances which may under some circumstances behave in a similar manner. Where any doubt exists about the existence of hazard due to explosive properties, expert advice should be sought.

This document describes a test method for the determination of the maximum explosion pressure of dust clouds in a closed vessel under defined initial conditions of pressure and temperature.
This method is not suitable for use with recognised explosives, like gunpowder and dynamite, substances which do not require oxygen for combustion, pyrophoric substances, or substances or mixtures of substances which may under some circumstances behave in a similar manner. Where any doubt exists about the existence of hazard due to explosive properties, expert advice should be sought.

This standard describes a test method for the determination of the maximum rate of explosion pressure rise of dust clouds in a closed vessel under defined initial conditions of pressure and temperature.
This method is not suitable for use with recognised explosives, like gunpowder and dynamite, explosives which do not require oxygen for combustion, pyrophoric substances, or substances or mixtures of substances which may under some circumstances behave in a similar manner. Where any doubt exists about the existence of hazard due to explosive properties, expert advice should be sought.

This European Standard specifies a test method to determine the explosion points of flammable liquids in air. This European Standard applies to flammable liquids at atmospheric pressure and at temperatures in the range from ­ 50 °C to 300 °C.
This European standard must not be applied to explosives or materials which, under the test conditions, are thermally unstable liquids (e.g. polymerizing/oxidizing materials).

This European Standard describes the general requirements for explosion isolation systems. An explosion isolation system is a protective system, which prevents an explosion pressure wave and a flame or only a flame from propagating via connecting pipes or ducts into other parts of apparatus or plant areas. This European Standard specifies methods for evaluating the efficacy of the various explosion isolation systems, and methods for evaluating design tools for such explosion isolation systems when applying these in practice.
This European Standard also sets out the criteria for alternative test methods and interpretation means to validate the efficacy of explosion isolations.
It covers e.g.:
a)   general requirements for the explosion isolation components;
b)   evaluating the effectiveness of an explosion isolation system;
c)   evaluating design tools for explosion isolation systems.
This European Standard is applicable only to the use of explosion isolation systems that are intended for avoiding explosion propagation between interconnected enclosures, in which an explosion may result as a consequence of ignition of an explosive mixtures e.g., dust-air mixtures, gas-(vapour-)air mixtures, dust-, gas-(vapour-)air mixtures and mists.
In general explosion isolation systems are not designed to prevent the transmission of fire or burning powder either of which can initiate an explosion in downstream plant items. It is necessary to take this situation into account in risk assessments.
This European Standard is only applicable for gas and dust explosions of chemically stable substances and mixtures of these (flame propagating at subsonic velocity).
This European Standard is not applicable for explosions of materials listed below, or for mixtures containing some of those materials:
i)   chemically unstable substances that are liable to decompose;
ii)   explosive substances;
iii)   pyrotechnic substances.

BSI - Translation improvements in 4.2.1 and 7.1
2013: Originator of XML version: first setup pilot of CCMC in 2012

This European Standard provides guidance on the procedure and information required to allow functional safety assessment to be carried out for the design of protective systems.
The purpose of this European Standard is to assist technical standardization committees responsible for specific families of protective systems in preparing safety standards. Such standards shall be as homogenous as possible and shall have the basic structure of functional safety assessment as it is stated in this standard.
If there are no specific standards for a particular protective system, the manufacturer shall use this standard for functional safety assessment of this protective system.
In this procedure the following information is to be taken into account to ensure a sufficient level of functional safety:
a)   intended use,
b)   possible operating faults,
c)   reliability of protective systems,
d)   misuse which can reasonably be anticipated.
A sufficient level of functional safety is characterized by the following objectives:
1)   System can stop an explosion at a very early stage or reduce the impact of an explosion to an acceptable level.
2)   In the event of faults, failures and/or interference ) the capacity to function remains effective by use e.g. of fail safe techniques or redundancy.
This European Standard does not cover identification of possible ignition sources.
NOTE 1   The identification of possible ignition sources is covered by EN 15198.
This European Standard only deals with the functional behaviour of the protective system i.e. hazards caused by malfunctions, e.g. false activations are excluded.
This European Standard specifies neither specific methods to analyse fault conditions, nor specific requirements for a given type of protective system (see EN 1127 1). It specifies the methodology of functional safety assessment.
(continued)

This European Standard specifies basic methodology used in achieving safety of equipment for intended use in potentially explosive atmospheres.
The provisions specified in this European Standard are intended for the designer. It also specifies a strategy for standard makers.
This European Standard specifies the procedure and information required to allow ignition risk assessment to be carried out for the design of equipment or component.
This European Standard provides advice for a decision to be made for the categorisation of equipment but does not provide means to prove the conformity of equipment categories.
In this procedure the following information is to be taken into account:
a)   Possible occurrence of an explosive atmosphere inside the equipment or component or penetrating the equipment or component from the outside (in normal operation or during malfunctions) and the amount of explosive atmosphere involved leading to possible explosion impact inside of the equipment or component;
b)   equipment or components surrounded by an explosive atmosphere (in normal operation or during malfunctions);
c)   equipment or components wholly or partly surrounded by an explosive atmosphere considering also any explosive atmosphere in connection (in normal operation or during malfunctions);
d)   presence and likelihood (effectiveness) of ignition sources.
The final objective is designing and manufacturing equipment or components intended for use in potentially explosive atmospheres. For this purpose equipment or components if necessary shall be designed with adequate preventive and/or protective measures.
This European Standard specifies neither specific methods of analysis associated with ignition risk assessment, nor specific requirements for a category of equipment. It describes the methodology of ignition risk assessment.
(continued)

This document lays down requirements for automatic explosion extinguishing systems for roadheader
machines (selective cut heading machines) in roadheader drivages where these systems automatically detect
the initial phase of a firedamp explosion which has been initiated by the cutter head of a roadheader machine
and extinguish it at the roadhead in such a way that the roadway drivage team is not put at risk.
This document does not lay down any requirements for the fighting of fires at the roadhead.
The automatic explosion extinguishing system for roadheaders is an autonomous protective system designed
in accordance with Directive 94/9/EC.

This standard specifies the requirements for concentrated and distributed passive water trough barriers, and quick-deploy water trough barriers.
This standard specifies the requirements and test methods for water troughs which are used as components of the "water trough barrier" protective system for underground coal mines.
This standard does not apply to active water trough barriers.

This European Standard specifies the basic design requirements for the selection of a gas explosion venting protective system. This European Standard, EN 14797 and EN 14460 form a series of three standards which are used together.
NOTE 1   These three standards together represent the concept of gas explosion venting.
NOTE 2   To avoid transfer of explosions to other communicating equipment one should also consider applying prEN 15089.
This European Standard is applicable to:
   vent sizing to protect against the internal pressure effects of a gas explosion;
   flame and pressure effects outside the enclosure;
   recoil forces;
   influence of vent ducts;
   influence of initial temperature and pressure.
This European Standard does not provide design and application rules against effects generated by detonation reactions or runaway exothermic reactions including decomposition in the gas phase.
This European Standard is not applicable to:
   fire risks arising either from materials processed, used or released by the equipment or from materials that make up equipment and buildings;
   design, construction and testing of explosion venting devices, which are used to achieve explosion venting );
   protection against overpressures caused by events such as overfilling, overpressurisation, fire engulfment, overheating etc.
NOTE 3   Protection by venting against dust and hybrid explosions is specified in EN 14491.

This European Standard specifies the requirements for venting devices used to protect enclosures against the major effects of internal explosions arising from the rapid burning of suspended dust, vapour or gas contained within. It includes the requirements for the design, inspection, testing, marking, documentation and packaging. This European Standard specifies explosion venting devices which are put on the market as autonomous protective systems.
Explosion venting devices are safety devices comprised of a pressure sensitive membrane fixed to and forming part of the structure that it protects, designed to intervene in the event of an explosion at a predetermined low pressure, to immediately open a vent area sufficient to ensure that the maximum pressure attained by the explosion within the enclosure does not exceed its designed resistance to pressure.
The application and specification of explosion venting devices is outlined for dust explosion protection in EN 14491 and for gas explosion protection in prEN 14994. The use of venting devices according to this European Standard on pipelines and on applications other than described in EN 14491 or prEN 14994 needs to be carefully evaluated and where appropriate their suitability needs to be confirmed by tests.
Flameless explosion venting devices avoid the breakthrough of flames into the surroundings. They are used to allow explosion venting in situations where the hazards of flames resulting from the venting action are not acceptable. Flameless explosion venting devices are treated in a separate standard.
This European Standard does not cover details for the avoidance of ignition sources from detection devices or other parts of the venting devices.

EC - Annex ZA in line with latest requirements

This document applies to air shutter frames and air doors for ventilation structures which are to remain functional after the passage of explosions with overpressures of up to 2 bar.
Ventilation structures are protective systems to provide the ventilation flow after the occurrence of an explosion such that the effects of an explosion on the ventilation system can be limited and adequate possibilities remain for escape and rescue.
NOTE   These structures may be used when ventilation studies indicate that the air flow in the work place would be reduced considerably providing no safe escape for workers in cases where the structure is destroyed. Explosion proof ventilation structures will be individually evaluated for directional stability of ventilation flows and in order to ensure adequate ventilation flows.

This document specifies the general requirements for explosion isolation systems. An explosion isolation system is an autonomous protective system which aims to prevent an explosion pressure wave and a flame or only a flame from propagating via connecting pipes or ducts into other parts of apparatus or plant areas.
This document also specifies methods for evaluating the efficacy of the various explosion isolation systems, and methods for evaluating design tools for such explosion isolation systems when applying these in practice.
This document also sets out the criteria for alternative test methods and interpretation means to validate the efficacy of explosion isolation systems.
This document does not cover flame arresters, diverters, and explosion isolation flap valves. For these devices refer to EN ISO 16852:2016 , EN 16020:2011, and EN 16447:2014 respectively.
This standard covers e.g.:
a)   general requirements for the explosion isolation components;
b)   evaluating the efficacy of an explosion isolation system;
c)   evaluating design tools for explosion isolation systems.
This document is applicable only to the use of explosion isolation systems that are intended for avoiding explosion propagation between interconnected enclosures, in which an explosion can result as a consequence of ignition of explosive mixtures, e.g. dust-air mixtures, gas-(vapour-)air mixtures, dust-, gas-(vapour-)air mixtures and mists. It is not applicable to detonation events.

This document describes the basic requirements for the design and application of explosion suppression systems. This document also specifies test methods for evaluating the effectiveness and the scaling up of explosion suppression systems against defined explosions. This document covers:
-   general requirements for explosion suppression system parts;
-   evaluating the effectiveness of an explosion suppression system;
-   evaluating the scale up of an explosion suppression system to larger than tested volumes;
-   development and evaluation of design tools for explosion suppression systems;
-   installation, operation and maintenance instructions for an explosion suppression system.
This document is applicable only to explosion suppression systems intended for the protection of closed, or essentially closed, enclosures in which an explosion could result as a consequence of ignition of an explosible mixture, e.g. dust-air, gas(vapour)-air, dust-gas(vapour)-air and mist-air.
This document is not applicable for explosions of materials listed below, or for mixtures containing some of those materials:
-   unstable materials that are liable to dissociate;
-   explosive materials;
-   pyrotechnic materials;
-   pyrophoric materials.

This part of ISO/IEC 80079 covers the technical requirements necessary to avoid or minimize the significant hazards listed in Clause 4, which could occur during normal operation, maintenance or foreseeable malfunction of reciprocating internal combustion engines intended for use in explosive atmospheres including
- Group I EPL Mb for use in underground workings susceptible to firedamp and/or combustible dust,
- Group II EPL Gb and Gc for use in potentially explosive atmospheres of flammable gas and vapour and
- Group III EPL Db and Dc for use in potentially explosive atmospheres of combustible dust.
This part of ISO/IEC 80079 includes those tests of the engine and its ancillary devices that are required to verify compliance.
This part of ISO/IEC 80079 applies to reciprocating internal combustion engines with compression ignition and spark ignition.
This part of ISO/IEC 80079 does not define requirements relating to the driven machinery and equipment.
This part of ISO/IEC 80079 does not apply
- to flammable gas and vapour atmospheres containing carbon disulphide (CS2) and/or ethylene oxide (C2H4O) due to special properties of these gases;
- to explosive mixtures of vapours and gases, which tend to self-decompose (e.g. acetylene) or which are chemically unstable.This International standard does not apply to engines used in areas for the processing manufacture or storage of explosives;
- to gasoline engines and all other liquid injection spark ignited engines.
This part of ISO/IEC 80079 solely deals with explosion protection requirements. Requirements on emissions are not covered by this standard.
General safety requirements are not included in this International Standard.
NOTE 1   General safety requirements i.e. those common to internal combustion engines, are covered for the EU in EN 1679-1:1998+A1:2011.
This part of ISO/IEC 80079 does not specify requirements for safety, other than those directly related to the risk of ignition which may then lead to an explosion.The standard atmospheric conditions (relating to the explosion characteristics of the atmosphere) under which it may be assumed that engine can be operated are:
- temperature -20 °C to +40 °C;
- pressure 80 kPa (0,8 bar) to 110 kPa (1,1 bar); and
- air with normal oxygen content, typically 21 % v/v.
Such atmospheres can also exist inside the engine. In addition, the external atmosphere can be drawn inside the engine by natural breathing produced as a result of fluctuations in the engine's internal operating pressure, and/or temperature.
NOTE 2   It is considered that −20 °C to +40 °C is appropriate for most engines. However for equipment designed for outside this range IEC/TS 60079-43 should be considered.
NOTE 3   The requirements of this standard can also be helpful for the design, construction, testing and marking of engine intended for use in atmospheres outside the validity range stated above. In this case however, the ignition hazard assessment, ignition protection provided, additional testing (if necessary), manufacturer’s technical documentation and instructions to the user, should clearly demonstrate and indicate the engine's suitability for the conditions it may encounter. It should also be recognized that changes in temperature and pressure can have a significant influence on characteristics of the explosive atmosphere, such as ignitability (see Annex I).
NOTE 4   Reciprocating internal combustion engines are not considered as pressure vessels.