CEN/TC 305/WG 3 - Devices and systems for explosion prevention and protection (provisional title)

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 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.

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.

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 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 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 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.

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.

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 measure to prevent explosions. By feeding inert gas into a system which is to be protected against an explosion, the oxygen content is reduced below a certain concentration until no explosion can occur. The addition of sufficient inert gas to make any mixture non-flammable when mixed with air (absolute inerting) is only required in rare occasions. The requirements for absolute inerting will be discussed. Inerting may also be used to influence the ignition and explosion characteristics of an explosive atmosphere.
The guidance given on inerting is also applicable to prevent an explosion in case of a fire.
The following cases are not covered by the guideline:
-   admixture of an inert dust to a combustible dust;
-   inerting of flammable atmospheres by wire mesh flame traps in open spaces of vessels and tanks;
-   fire fighting;
-   avoiding an explosive atmosphere by exceeding the upper explosion limit of a flammable substance.
Inerting which is sufficient to prevent an explosion is not a protective measure to prevent fires, self-ignition, exothermic reactions or a deflagration of dust layers and deposits.

This European Standard describes the basic requirements for the design and application of explosion suppression systems. This European Standard also specifies a method for evaluating the effectiveness and the scale up of explosion suppression systems against defined explosions. It gives the criteria for alternative test apparatus used to undertake explosion suppression efficacy tests and criteria to be applied in defining the safe operating regime of an explosion suppression system.
It covers:
   general requirements for explosion suppression components;
   evaluating the effectiveness of an explosion suppression system;
   evaluating the scale up of an explosion suppression system;
   evaluation and development of design tools for explosion suppression systems;
   instructions for installation of an explosion suppression system;
   maintenance instructions for an explosion suppression system.
This European Standard is applicable only to explosion suppression systems intended for the protection of closed, or essentially closed, enclosures in which an explosion may result as a consequence of ignition of an explosible mixtures, e.g. dust-air mixtures, gas(vapour)-air mixtures, dust-gas(vapour)-air mixtures and mists.
This European Standard 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.
NOTE   For the listed materials expert advice is required.

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.

This standard specifies requirements for explosion-pressure-resistant and explosion pressure shock-resistant equipment. This standard is applicable to process vessels and systems. It is not applicable to individual items of equipment such as motors and gearboxes that may be designed to withstand an internal explosion, which are the subject of EN 13463-3.
This standard is valid for atmospheres having pressures ranging from 800 hPa to 1100 hPa 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 detonation may occur. This standard should not be used for offshore applications.
It is essential that this standard be used for equipment made of metallic materials only.

TC/AFNOR/DIN - Various editorial improvements including the corrections of 1st Corrigendum EN 14491:2006/AC:2008, WI 00305C03

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 prEN 14797 Explosion venting device and prEN 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 prEN 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.
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 either materials processed, used or released by the equipment or 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).

This standard specifies the requirements for flame arresters which prevent flame transmission when flammable gas/air- or vapour/air-mixtures are present. It establishes uniform principles for the classification, basic construction and marking of flame arresters and specifies test methods to verify the safety requirements and determine safe limits of use. This standard does not cover the following:
- External safety-related measurement and control equipment which may 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 (e.g
acetylene) or which are chemically unstable. - Flame arresters used for carbon disulphide due to its special properties. - Flame arresters used for gas or vapour mixtures containing more than the atmospheric oxygen concentration. - Flame arrester test procedures for internal combustion, compression ignition engines. Refer to EN 1834-1 and EN 1834-2. The safety factors incorporated into the tests specified in this standard mean that the uncertainty of measurement inherent in good quality, regularly calibrated measurement equipment is not considered to have any significant detrimental effect on the results and need not be taken into account when making the measurements necessary to verify compliance of the flame arrester with the requirements of this standard.

Per BT C012/2006 transfer of responsibility from CEN/TC 191 to CEN/TC 305.