Guide to application of the ATEX 2014/34/UE directive - ANNEX II ESSENTIAL HEALTH AND SAFETY REQUIREMENTS

ANNEX II

ESSENTIAL HEALTH AND SAFETY REQUIREMENTS RELATING TO THE DESIGN AND CONSTRUCTION OF EQUIPMENT AND PROTECTIVE SYSTEMS INTENDED FOR USE IN POTENTIALLY EXPLOSIVE ATMOSPHERES

§ 139  Essential health and safety requirements

Annex II to the ATEX Directive 2014/34/EU provides an overview of the essential health and safety requirements (EHSRs) to be adopted to avoid the risk of explosion. Although direct application of the EHSRs is possible, it is envisaged that the normal route to demonstrate conformity with the EHSRs will be to conform to the requirements given in one or more European harmonised standards (see section § 62). If European harmonised standards are not used, it is incumbent on the person declaring conformity to state the technical basis for such a declaration, including evidence of any research that might have been undertaken in order to prove the equivalence of the protective measures undertaken.

Preliminary observations

A.          Technological knowledge, which can change rapidly, must be taken into account as far as possible and be utilized immediately.

B.           For the devices referred to in point (b) of Article 1(1), the essential health and safety requirements shall apply only in so far as they are necessary for the safe and reliable functioning and operation of those devices with respect to the risks of explosion.

§ 140  Preliminary observations

Preliminary observation “A” is often referred to as requiring conformity with the “state of the art”. Although the generalised text of the EHSRs does not change, the European harmonised standards interpreting the EHSRs are subject to a continuous process of revision to take into account developments in technology and further developments in knowledge about explosion protection.

Therefore, the relevant current harmonised standards would be regarded as demonstrating “state of the art” for a particular type of protection. Use of a non-harmonised standard may be possible, but its use must be justified.

Further information on issues relating to “state of the art” and EU-type examination certificates can be found in the Clarification Sheet ExNB/10/397/CS issued by the European Coordination of ATEX Notified Bodies Group (ExNBG), available on http://ec.europa.eu/DocsRoom/documents/9568/attachments/1/translations/en/renditions/native.

Preliminary observation “B” indicates that safety devices, controlling devices and regulating devices – referenced in Article 1(1)(b) – need only to comply with a restricted range of EHSRs and that conformity to the remaining EHSRs will be ascertained when the conformity of the complete equipment, incorporating the component, is assessed.

1.         Common requirements for Equipment and protective systems

1.0.      General requirements

§ 141  General requirements

In general terms, it can be stated that compliance with the essential health and safety requirements of Directive 2014/34/EU is imperative in order to ensure the explosion proofing of equipment and protective systems. The requirements are intended to take account of existing or potential hazards deriving from the design and construction. However, following the philosophy of the ATEX Directive 2014/34/EU within the New Approach and New Legislative Framework, the notion of intended use is of prime importance too. It is also essential that manufacturers supply full information.

1.0.1.     Principles of integrated explosion safety

              Equipment and protective systems intended for use in potentially explosive atmospheres must be designed from the point of view of integrated explosion safety.

              In this connection, the manufacturer must take measures:

              – above all, if possible, to prevent the formation of explosive atmospheres which may be produced or released by equipment and by protective systems themselves,

              – to prevent the ignition of explosive atmospheres, taking into account the nature of every electrical and non-electrical source of ignition,

              – should an explosion nevertheless occur which could directly or indirectly endanger persons and, as the case may be, domestic animals or property, to halt it immediately and/or to limit the range of explosion flames and explosion pressures to a sufficient level of safety.

1.0.2.     Equipment and protective systems must be designed and manufactured after due analysis of possible operating faults in order as far as possible to preclude dangerous situations.

              Any misuse which can reasonably be anticipated must be taken into account.

§ 142  Principles of integrated explosion safety. Risk assessment for ATEX products

To meet the requirements of Directive 2014/34/EU it is necessary to conduct a risk assessment process. According to Annex II, 1.0.1 manufacturers are under an obligation to design equipment and protective systems from the point of view of integrated explosion safety. Integrated explosion safety is conceived to prevent the formation of explosive atmospheres as well as sources of ignition and, should an explosion nevertheless occur, to halt it immediately and / or to limit its effects. In this connection, the manufacturer must take measures with respect to the risks of explosion. However, in most cases he will not be in the position to understand the possible extent of the adverse consequences of an explosion (as part of the overall explosion risk) since this is solely dependent on the particular circumstances at the users` premises. So the manufacturer's risk assessment will in general be restricted to and be focussed on the assessment of the ignition hazard (again part of the explosion risk) or the explosion control function for a protective system and safety devices. In addition, as required in Annex II, 1.0.2 to the Directive, equipment and protective systems must be designed and manufactured after due analysis of possible technical and operating faults in order as far as possible to preclude dangerous situations.

Bearing in mind the commitments resulting from the relevant requirements of Directive 2014/34/EU, a methodology on risk assessment, i.e. here ignition risk assessment, should not only deal with designing and construction aspects but also provide a common format or language between designers and users.

Methods and/or techniques that could be applied

There are many possible methods and/or techniques for risk assessment, especially for hazard identification. They can easily be adopted for the ignition risk assessment explained above as follows.

A good identification technique has the following attributes:

- it is systematic, i.e. it guides the parties concerned so that all parts of the system, all phases of use and all reasonably anticipated hazards are considered;

- it employs brainstorming.

By using more than one technique the possibility of overlooking any relevant hazard is minimised. However, the additional time employed in using more than one technique needs to be balanced against the increased confidence in the results. The main output from the hazard identification stage is a numbered listing of hazardous events, which could result from the products involved as an input to the risk estimation stage.

Risk assessment methodology should comprise the hazard profiles including the accidental parameters that can reasonably be anticipated. These aspects become subject to a risk assessment as a “series of logical steps to enable, in a systematic way, the examination of the hazards associated with products”.

In principle the risk assessment comprises of four steps[1]:

  1. Hazard identification: a systematic procedure for finding all of the hazards, which are associated with the products. Once a hazard has been recognized, the design can be changed to minimise it, whether or not the degree of risk has been estimated. Unless the hazard is recognized it cannot be addressed in the design.
  2. Risk estimation: determination of the probability of occurrence of the identified hazards (and of the levels of severity of the possible harm of the considered hazards)[2].
  3. Risk evaluation: comparison of the hazards estimated with criteria in order to decide whether the risk is acceptable or whether the product design must be modified in order to reduce the risk.
  4. Risk reduction option analysis: the final step of risk assessment is the process of identifying, selecting and modifying design changes which might reduce the overall risk from products. Although risks can always be reduced further they can seldom be reduced to zero except by eliminating the activities.

Options, which address the hazardous events that make the greatest contributions to the total risk, have the greatest potential to reduce risk. Effectiveness in reducing risk always starts with changes to the design concept, i.e. inherently safe design.

See also §§ 4.1.1 "Definition of essential requirements", 4.1.2.2. "Role of harmonised standards" and 4.3 "Technical documentation" in “The 'Blue Guide' on the implementation of EU product rules”.

 

1.0.3.     Special checking and maintenance conditions

              Equipment and protective systems subject to special checking and maintenance conditions must be designed and constructed with such conditions in mind.

1.0.4.     Surrounding area conditions

              Equipment and protective systems must be so designed and constructed as to be capable of coping with actual or foreseeable surrounding area conditions.

§ 143  Special conditions: checking, maintenance, surrounding area

Special conditions on checking, maintenance and the surrounding area for ATEX products are usually related to their intended use. In this sense it would be useful to ensure good communication between the manufacturer and the intended user of the product, in order to take into due consideration such conditions in the design and construction phases and to inform the users accordingly in terms of health and safety.

The surrounding area conditions may include:

  • ambient temperature range;
  • the effect of additional sources of heat or cooling (such as mounting on a heated process vessel);
  • exposure to known chemical agents (including a salt atmosphere);
  • exposure to vibration or other physical forces (including impact);
  • exposure to light (particularly relevant for plastic materials).

1.0.5.     Marking

              All equipment and protective systems must be marked legibly and indelibly with the following minimum particulars:

              –        name, registered trade name or registered trade mark, and address of the manufacturer,

              –        CE marking (see Annex II to Regulation (EC) No 765/2008),

              –        designation of series or type,

              –        batch or serial number, if any,

              –        year of construction,

              –        the specific marking of explosion protection      followed by the symbol of the equipment group and category,

              –        for equipment-group II, the letter ‘G’ (concerning explosive atmospheres caused by gases, vapours or mists),

                        and/or

              –        the letter ‘D’ (concerning explosive atmospheres caused by dust).

              Furthermore, where necessary, they must also be marked with all information essential to their safe use.

§ 144  Marking

As these ATEX Guidelines have been especially drafted to facilitate the application of Directive 2014/34/EU, the following explanations refer only to this Directive. If other directives are applicable in parallel, their provisions have to be taken into account in addition to those of Directive 2014/34/EU.

The ATEX Directive prescribes, within the essential health and safety requirements, a set of markings for equipment and protective systems, including in particular CE marking and other supplementary/specific marking.

See also § 4.5 “Marking requirements” in “The ‘Blue Guide’ on the implementation of EU product rules”.

§ 145  CE Marking

See also section § 67 on CE marking.

Regulation (EC) No 765/2008 lays down the definition, the format and the general principles governing the CE marking.

CE marking is used by the manufacturer as a declaration that he considers that the product in question has been manufactured in conformity with all applicable provisions and requirements of the ATEX Directive 2014/34/EU and that the product has been the subject of the appropriate conformity assessment procedures.

The CE marking is mandatory and must be affixed before any equipment or protective system is placed on the market or put into service. As stated in Article 13(3) components are excluded from this provision. Instead of being CE marked, components have to be delivered with a written attestation stating the conformity with the provisions of the Directive, stating their characteristics and indicating how they must be incorporated into equipment or protective systems. This separate statement goes along with the definition of components, which have as structural parts no autonomous function.

In general the CE marking must be affixed during the production control phase by the manufacturer or his authorised representative established within the European Union. In certain cases it is possible to affix the CE marking earlier, e.g. during the production phase of a complex product (e.g. a vehicle). It is then necessary that the manufacturer formally confirms the compliance of this product with the requirements of the Directive in the production control phase.

The CE marking must consist of the initials "CE" taking the form described in Regulation (EC) No 765/2008. In general the CE marking must be affixed to the product or to its data plate. However, although it is not a requirement in Directive 2014/34/EU, it is considered reasonable to affix the CE marking to the packaging and to the accompanying documents if it is not possible to affix it to the product because of the product's size or nature.

It would be sensible, but it is not mandatory, to affix the CE marking to more than one place, for example, marking the outer packaging as well as the product inside, would mean that the marking can be ascertained without opening the package.

The CE marking shall be affixed distinctly, visibly, legibly and indelibly. It is prohibited to affix any marks or inscriptions that are likely to mislead third parties as to the meaning and form of the CE marking. The requirement for visibility means that the CE marking must be easily accessible for market surveillance authorities as well as visible for customers and users. For reasons of legibility a minimum height of 5 mm of the CE marking is required. This minimum dimension may be waived for small-scale products. The requirement for indelibility means that the marking must not be removed from the product without leaving traces noticeable under normal circumstances.

Depending on the conformity assessment procedure applied, a notified body may be involved in the design phase (Annex III), the production phase (Annexes IV, V, VI, VII, IX) or in both phases. The identification number of the notified body only has to accompany the CE marking if the body is involved in the production control phase. It is necessary to avoid any misleading information on equipment, for example the number of the notified body, where this is not foreseen by the Directive. Hence, the product should not have the number of a notified body affixed, if falling under category 3 (other than Unit verification), as well as some category 2 equipment, and for any voluntary certification.

The CE marking and the identification number of the notified body do not necessarily have to be affixed within the territory of the EU. These can be affixed in a third country if the product, for example, is manufactured there and the notified body either performed tests on the product type or assessed the quality assurance system of the manufacturer in that country. The CE marking and the identification number can also be affixed separately, so long as the CE and body-number remain combined. In case of components only the identification number of the notified body has to be affixed.

Where equipment that has already been placed on the market is incorporated into a product (e.g. an assembly – see section § 45), the integrated equipment must bear the CE marking and, if appropriate, the identification number of the notified body.

Whilst it is recognised that sub-assemblies may have CE marking affixed in their own right these might not be visible following construction of the final product. This is acceptable as this information can be found elsewhere. However, the final product must have a single label clearly relating to its final assembly prior to it being placed on the market and/or taken into service. In affixing the CE marking to the final product the manufacturer or his authorised representative accepts full responsibility for the conformity of the final product to the applicable essential health and safety requirements of Directive 2014/34/EU and all other relevant European legislation.

§ 146  Supplementary/specific marking

It is the intention of Directive 2014/34/EU that the design of the specific marking of explosion protection  follows the design, as specified in the old Directive 84/47/EEC (see page 229). This marking has to be followed by the symbol of the group and category (on devices according to Article 1(1)(b) of Directive 2014/34/EU the category should be indicated in brackets) and, relating to group II, the letter ‘G’ (concerning explosive atmospheres caused by gases, vapours or mists) and/or D (concerning explosive atmospheres caused by dust).

User instructions shall explain in detail the meaning of the marking on the product. However it is recommended to use the format provided in the following examples, as in Tables 6 and 7, where

" .. / .. " means the product has two different categories, and

".. - .. " means that a part of the product is not conforming to the Directive and not intended to be used in a potentially explosive atmosphere.

Moreover, devices according to Article 1(1)(b) of the Directive, and separately placed on the market, shall be marked with the category of the equipment under control in round brackets, and such devices which contain an own potential ignition source intended for use in a potential explosive atmosphere shall be marked as equipment according to Annex II clause 1.0.5.

 

Table 6: examples for marking of equipment

I

M2

Mining products, group I, category M2

II

1 G

Non-mining products, group II, category 1 for use in gas/vapour/mist atmospheres

II

1 D

Non-mining products, group II, category 1 for use in dust atmospheres

 

 

Protective system, for use in gas/vapour/mist/dust atmospheres

II

(1) G D

Device according to Article 1(1)(b) of Directive 2014/34/EU in the non-hazardous area with intrinsically safe circuits of category "Ex ia", which can be connected e.g. to category 1 equipment

II

2 GD

Category 2 equipment for use in potentially explosive atmosphere containing gases or dust

II

(2)/2 (1)/1 G

An assembly, such as a gas detection system with more than one detection head, that is partly category 1 and partly category 2 formed by a safety device and an equipment. The safety device is intended for use outside the hazardous area and the equipment is intended for use inside hazardous area

II

2(1) G

Category 2 equipment containing a safety device for a category 1 equipment

II

2(1) GD

Same equipment for gas or dust potentially explosive atmospheres

II

(2) G (1) G

A safety device alone which ensures the safety against explosion for category 1 equipment and for another category 2 equipment

II

3/3 D

A blower exhausting out of zone 22 and to be installed in zone 22

 

Table 7: examples for marking of equipment having different categories

II

1/2 G

Level gauge installed in the tank wall between zone 0 and zone 1

II

(2) 3 G

An electrical field bus device affecting category 2 equipment installed in zone 2

II

2/- G

A ventilator exhausting out of zone 1 but to be installed outside potentially explosive atmospheres. The Directive has no provisions for marking in case of installation outside potentially explosive atmospheres

II

2/3 G

A ventilator extracting out of zone 1 but to be installed in zone 2

II

3/- D

A screw conveyor conveying dust out of a zone 22 but installed outside potentially explosive atmospheres. The Directive has no provisions for marking in case of installation outside potentially explosive atmospheres

II

-/2 D

Blower conveying no explosive atmosphere but to be installed in zone 21

Note: In the above examples, where a zone is indicated, the “normal” correspondence between zone and category is assumed according to the ATEX “workplace” Directive 1999/92/EC, i.e.

  • category 1 - zone 0 or 20
  • category 2 - zone 1 or 21
  • category 3 - zone 2 or 22

 

 

All products must be marked with the registered name (or registered trade mark) and address of the manufacturer, designation of series or type, serial number (if any) and the year of construction. The year of construction and serial number may be combined or in a conventional coded format, in which case the explanation of the code shall be given in the instructions accompanying the product.

Where more than one category is given in the marking, the product must be accompanied with written information explaining the different categories, where they apply, and the consequences for the intended use.

Where a product is covered by more than one New Approach / New Legislative Framework legal act (European Regulation or Directive), CE marking denotes compliance with the appropriate provisions of all relevant directives. However, where one or more of these directives are in their transitional period and, as a consequence, allow the manufacturer to choose which arrangements to apply, the CE marking indicates conformity only to those directives where application is mandatory and others which are so applied. In the case of these latter directives particulars must be given in the documents, notices or instructions accompanying the product or, where appropriate, on the data plate.

§ 147  Additional marking for standards

Because of the special importance for the safety of products intended for use in potentially explosive atmospheres and in order to avoid any misunderstandings, Directive 2014/34/EU provides for additional markings (see Annex II 1.0.5.).

Equipment, protective systems and components must furthermore be marked with all necessary information essential to the safe use. According to this requirement European standards for electrical and non-electrical products for potentially explosive atmospheres foresee a supplementary marking. For detailed and complete information about this marking it is necessary to use these standards.

It is a requirement that the standard marking should not be used in a way that can allow it to be confused with the mandatory marking. Therefore, it is recommended in the standards that the legal marking of the directive and the additional marking required by the standards remain separate in order to avoid possible confusion.

Further, the standards often recommend that marking for protection against gas hazards and against dust hazards should be presented separately, to avoid confusion, whereas the directive recommends that a single legal marking, incorporating the letters “GD” be applied.

§ 148  Marking of small products

In accordance with the general guidance given to the CE marking of products, it is considered reasonable to affix all other marking to the packaging and the accompanying documents if it is not possible to affix it to the product because of the product's size or nature. The marking on the product may not be reduced or moved to the packaging purely on aesthetic grounds.

On very small products where a reduction in the marking is unavoidable, the following information is nevertheless required:

- CE marking (not for components),

- ex marking (epsilon-x, within the hexagon), and

- the name or registered trade mark of the manufacturer.

Where possible, at least a simplified address should also be given, sufficient for mail to reach the company. An internet address is not sufficient but the postal address has to be given. In some countries a unique postal code identifies an address. The use of this postal code is sufficient with the country.

§ 149  Marking of components

The ATEX Directive 2014/34/EU explicitly requires marking in Annex II, clause 1.0.5., only for equipment and protective systems. The question, whether components should nevertheless be marked in order to facilitate the implementation to the Directive, has particular practical relevance in cases

- where it is difficult to recognise the difference between ATEX components and standard components, and

- where a manufacturer who wanted to use a component might have serious problems undertaking his risk assessment, if there is no indication about the category of the component.

Apart from the question of marking, the Directive requires a written attestation of conformity for components. The latter shall give all the necessary information stating the characteristics. This normally occurs assigning to the component an explosion classification according to relevant harmonised standards, which looks like a marking (e.g. Ex II 1/2 GD cb Tx or Ex II 1 GD c Tx).

For components having an own potential ignition source or which are clearly correlated (with respect to the properties of the component) to equipment with a given category, it has been considered that without the definition of group and category, the necessary conformity procedure of the equipment, which the component will be incorporated to, cannot be performed.

In some cases the conformity procedure can only be performed, if the equipment, which the component will be incorporated to, is defined, and if this incorporation is a matter of the conformity procedure.

Therefore, it is recommended to mark components, as long as these can be assessed with respect to a certain category and group of equipment, indicating this category and group in the marking.

It should be noted that, in most cases, a component will not be marked with a temperature class as it is not, itself, a source of heat, or the temperature can only be determined when fitted within the final equipment.

Moreover, it is recommended to mark components for autonomous protective systems, which can be assessed with respect to the characteristic properties of the latter, as far as reasonable indicating these characteristics in the marking.

In any case, according to Directive 2014/34/EU, ATEX components shall not bear the CE-marking.

Marking of components with the Notified body's number

It has been discussed whether components subject to NB assessment required by the Directive should be marked with the notified body's identification number.

According to Article 1(1) the ATEX Directive 2014/34/EU applies to equipment, protective systems, safety devices and protective devices, and to components, under the generic denomination of "products". Hence, the provisions of the Directive which apply to "products" apply also to components unless otherwise specified.

The wording of Article 13(3) confirms that it is the intention of the legislator to treat components as products in general, but for those specific cases where explicit exceptions were defined. This is exclusively true for the CE marking (not allowed), and the name of the document by which the conformity is declared (attestation of conformity instead of EU declaration of conformity).

The requirement concerning the marking with the notified body's identification number is addressed in Article 16(3) of the Directive, providing that, where the body is involved in the production control phase, the identification number of the notified body must be affixed following the CE marking. It is clear from the wording of the referred article that CE marking and the marking with the notified body's identification number are two separate requirements.

It is therefore evident that:

- the notified body's identification number shall be placed on components, e.g. when required by the conformity assessment procedures required in Annexes VI or IX;

- although the CE marking requirement does not apply to components due to the specific provisions of Article 13(3), in the absence of an explicit provision to the contrary, Article 38(1)(d) shall be applied also to components;

- Member States shall act on the basis of Article 38(1)(d) against non-compliant components in the same way as against non-compliant equipment or protective systems;

- whenever notified bodies are involved in the production control phase of components, the notified body's identification number should also be placed on that component as required in Article 16(3), but certainly without the CE marking.

§ 150  Marking of assemblies

The marking of assemblies is identical to the marking of equipment, in particular equipment having different categories. An assembly may consist of a large number of assessed and compliant items (equipment, protective systems, safety devices) with their own specific marking, potentially of different categories. In such cases it would not be helpful to show all of these the individual markings in the marking of the complete assembly. Nevertheless, the marking of the assembly has to display all relevant information required by Annex II, 1.0.5, of Directive 2014/34/EU necessary for the intended use of the assembly as a whole. The marking shall be placed in such a way – e.g. on the outer housing of the assembly – so that there is no doubt that it shows the characteristics of the whole assembly and not just one part.

Assemblies may consist of parts of different categories and be intended for potentially explosive atmospheres having different physical characteristics. The marking of the assembly as a whole with group, categories and additional information essential for the safe use of the assembly (temperature class, etc.) may fall under one of the two following scenarios:

Case 1: The assembly as a whole is intended for use in one potentially explosive atmosphere of one specific zone

Where the individual parts of the assembly are marked for potentially explosive atmospheres having different characteristics, the part with the lowest level of safety defines the marking of the whole assembly. That means that the category, temperature class, explosion group etc. with the lowest requirement for the equipment has to be used for the marking of the whole assembly.

Case 2: Parts of the assembly are intended for use in potentially explosive atmospheres having different physical characteristics and/or different zones

If it is essential for that intended use, the marking of the assembly shall contain all groups, categories and additional markings (temperature class, etc.) necessary for the intended atmospheres. In this case, the instructions for use, installation etc. will indicate the different atmospheres/zones intended (and/or provided by constructional measures) in or around different parts of the equipment.

Examples (only categories and additional markings essential for safe use are given in these examples):

For case 1:

  • An assembly consisting of parts marked with T3 and other parts with T6 shall be marked T3 to indicate, that it is, as a whole, intended for use in T3 atmospheres.
  • A pump unit consisting of a liquid pump (non-flammable liquid) and driving electric motor. The pump is marked II 2 G T6, the motor II 2 G IIB T4. The whole assembly shall be marked II 2 G IIB T4, as the motor is the part that meets the lower requirements.
  • A similar pump unit with a pump conveying hot liquid (non-flammable). The pump is marked II 2 G T3, the motor II 2 G IIB T4. In this case the assembly shall be marked II 2 G IIB T3.

For case 2:

  • A fan conveying an occasional IIA T3 explosive atmosphere (zone 1) in normal operation, the fan fitted with an electric motor and some control devices placed in a zone 2, the fan accordingly marked II 2/3 G IIA T3. The motor is marked II 3 G T3, the intrinsically safe control device II 2 G IIC T6. As the intrinsically safe control device is placed in the same atmosphere as the motor, the part meeting the lower requirements (in this case the motor) is the decisive item. Accordingly the marking of the whole assembly is II 2/3 G IIA T3.
  • A similar fan assembly, but with the motor placed outside the hazardous area. The marking of the whole assembly is II 2/3/- G IIA T3.

1.0.6.     Instructions

          (a)          All equipment and protective systems must be accompanied by instructions, including at least the following particulars:

          –   a recapitulation of the information with which the equipment or protective system is marked, except for the batch or serial number (see point 1.0.5), together with any appropriate additional information to facilitate maintenance (e.g. address of the repairer, etc.);

          –   instructions for safe:

              –       putting into service,

              –       use,

              –       assembling and dismantling,

              –       maintenance (servicing and emergency repair),

              –       installation,

              –       adjustment;

          –   where necessary, an indication of the danger areas in front of pressure-relief devices;

          –   where necessary, training instructions;

          –   details which allow a decision to be taken beyond any doubt as to whether an item of equipment in a specific category or a protective system can be used safely in the intended area under the expected operating conditions;

          –   electrical and pressure parameters, maximum surface temperatures and other limit values;

          –   where necessary, special conditions of use, including particulars of possible misuse which experience has shown might occur;

          –   where necessary, the essential characteristics of tools which may be fitted to the equipment or protective system.

          (b)          The instructions must contain the drawings and diagrams necessary for the putting into service, maintenance, inspection, checking of correct operation and, where appropriate, repair of the equipment or protective system, together with all useful instructions, in particular with regard to safety.

          (c)          Literature describing the equipment or protective system must not contradict the instructions with regard to safety aspects.

§ 151  Instructions

The ATEX Directive 2014/34/EU prescribes that equipment and protective systems must be accompanied by instructions, covering a wide range of contents. The manufacturer shall provide to the user written instructions that include the necessary information for safe use, repair, maintenance and/or overhaul of the equipment concerned, etc. The manufacturer does not have to provide the full technical file.

EHSR 1.0.6 does not specify the form of the instructions. It is generally agreed that all health and safety related instructions must be supplied in paper form, since it cannot be assumed that the user has access to the means of reading instructions supplied in electronic form or made available on an Internet site. This is particularly relevant for instructions that might need to be read whilst the plant is operational, in the presence of a potentially explosive atmosphere. However, it is often useful for the instructions to be made available in electronic form and on the Internet as well as in paper form, since this enables the user to download the electronic file if he so wishes and to recover the instructions if the paper copy has been lost. This practice also facilitates the updating of the instructions when this is necessary.

The user takes into account the instructions issued by the manufacturer to carry out repair, maintenance and/or overhaul on the basis of the requirements of the applicable directives (such as 2009/104/EC - Use of work equipment by workers at work and 1999/92/EC - Protection of workers potentially at risk from explosive atmospheres) and of relevant specific national legislation that regulates the repair, maintenance and overhaul of used equipment. The instructions must contain drawings and diagrams necessary for repair of the equipment. Applicable and technically accepted standards can also be used, for example EN 60079-19 - Explosive atmospheres - Equipment repair, overhaul and reclamation, which provides for identifying equipment that has been repaired to the manufacturer’s information separately from equipment that has been repaired “to standard”, i.e. the repairer’s “best guess” fit using the certification standard applicable to the equipment, but without access to the manufacturer’s instructions.

However, where necessary, the manufacturer can include in his documentation a statement that specific repair, maintenance and/or overhaul of the equipment shall only be conducted by the manufacturer himself, or by a repairer he has qualified or authorized.

With respect to assemblies, it is important to the safe installation, operation and maintenance of the assembled unit that all relevant information is passed to the end user. The manufacturer of the assembled unit should do this by including all related information in a package supplied to the end user.

With respect to instructions for components, see section § 47.

1.1.        Selection of materials

1.1.1.     The materials used for the construction of equipment and protective systems must not trigger off an explosion, taking into account foreseeable operational stresses.

1.1.2.     Within the limits of the operating conditions laid down by the manufacturer, it must not be possible for a reaction to take place between the materials used and the constituents of the potentially explosive atmosphere which could impair explosion protection.

1.1.3.     Materials must be so selected that predictable changes in their characteristics and their compatibility in combination with other materials will not lead to a reduction in the protection afforded; in particular, due account must be taken of the material's corrosion and wear resistance, electrical conductivity, mechanical strength, ageing resistance and the effects of temperature variations.

§ 152  Selection of materials

Guidance on selection of materials for the construction of ATEX equipment and protective systems is usually given in European harmonised standards, for example in relation to:

- avoidance of electrostatic ignition risks

- thermite reactions with aluminium, magnesium, titanium and zirconium

- light resistance

- thermal degradation resistance

- avoiding the use of copper in conjunction with acetylene

etc.

1.2.        Design and construction

1.2.1.     Equipment and protective systems must be designed and constructed with due regard to technological knowledge of explosion protection so that they can be safely operated throughout their foreseeable lifetime.

1.2.2.     Components to be incorporated into or used as replacements in equipment and protective systems must be so designed and constructed that they function safely for their intended purpose of explosion protection when they are installed in accordance with the manufacturer's instructions.

§ 153  Design and construction

The current state of technological knowledge is presumed to be given by using the relevant European harmonised standards.

1.2.3.     Enclosed structures and prevention of leaks

              Equipment which may release flammable gases or dusts must wherever possible employ enclosed structures only.

              If equipment contains openings or non-tight joints, these must as far as possible be designed in such a way that releases of gases or dusts cannot give rise to explosive atmospheres outside the equipment.

              Points where materials are introduced or drawn off must, as far as possible, be designed and equipped so as to limit releases of flammable materials during filling or draining.

§ 154  Enclosed structures and prevention of leaks

Although prevention of leaks is ideal, there are certain situations, for example in relation to the gassing of a battery during charging, where it is safer to securely vent the produced hazard rather than contain it.

1.2.4.     Dust deposits

              Equipment and protective systems which are intended to be used in areas exposed to dust must be so designed that deposit dust on their surfaces is not ignited.

              In general, dust deposits must be limited where possible. Equipment and protective systems must be easily cleanable.

              The surface temperatures of equipment parts must be kept well below the glow temperature of the deposit dust.

              The thickness of deposit dust must be taken into consideration and, if appropriate, means must be taken to limit the temperature in order to prevent a heat build up.

§ 155  Dust deposits

The relevant European harmonised standards providing protection against igniting an explosive dust atmosphere also address the relevant issues related to the ignition of dust layers.

1.2.5.     Additional means of protection

              Equipment and protective systems which may be exposed to certain types of external stresses must be equipped, where necessary, with additional means of protection.

              Equipment must withstand relevant stresses, without adverse effect on explosion protection.

§ 156  Additional means of protection

Additional means of protection for ATEX products are required in case of exposure to "certain types of external stresses", in principle distinct (and more severe) from general external stresses, according to the foreseeable conditions of use and operation. In any case, ATEX equipment must be able to resist against relevant stresses with no adverse effects on the required explosion protection.

1.2.6.     Safe opening

              If equipment and protective systems are in a housing or a locked container forming part of the explosion protection itself, it must be possible to open such housing or container only with a special tool or by means of appropriate protection measures.

§ 157  Safe opening

Relevant European harmonised standards give guidance on the use of fasteners and the tools that may be used to open them, as well as the use of interlocks as an alternative.

Even though there is now only "special fastenings", the three historic levels of "safe opening" are not precluded by this essential health and safety requirement 1.2.6 and it is not the intention of Directive 2014/34/EU to require a level of safety higher than that required by the EN 60079 series of standards for the equivalent zone of risk.

Level 1, the use of "Special Tools" e.g. on fasteners with hexagonal socket heads can still be used as specifically described by EHSR 1.2.6.

Level 2, the use of fasteners which require some form of tool to open the door e.g. a simple screwdriver, an adjustable spanner, or a key, are allowed in EHSR 1.2.6 where the additional "appropriate protection measure" would be the presence of a warning label requiring the operator to "De-energise before opening" or similar text.

Note: To qualify for Level 2 a "key" operated fastener (if used) should be used in conjunction with a lock mechanism that automatically locks the door in the closed position when the door is closed. The use of a lock which requires the use of a key to lock it in the closed position is not allowed for Level 2 since the operator may choose not to lock the door again when the door is closed and the additional protection required is no longer provided.

Level 3, the use of a door fastener which would allow the operator to open the door of the enclosure without the use of any tool i.e. with the "bare hands", is also not prevented by EHSR 1.2.6. However because of the increased personal and explosion risk additional measures have to be applied e.g. the use of an electrical or mechanical interlock to de-energise automatically the interior of the enclosure as well as the conspicuous presence of the warning label used in Level 2 above.

1.2.7.     Protection against other hazards

              Equipment and protective systems must be so designed and manufactured as to:

              (a)     avoid physical injury or other harm which might be caused by direct or indirect contact;

              (b)     assure that surface temperatures of accessible parts or radiation which would cause a danger, are not produced;

              (c)     eliminate non-electrical dangers which are revealed by experience;

              (d)     assure that foreseeable conditions of overload do not give rise to dangerous situations.

              Where, for equipment and protective systems, the risks referred to in this point are wholly or partly covered by other Union legislation, this Directive shall not apply or shall cease to apply in the case of such equipment and protective systems and of such risks upon application of that specific Union legislation.

§ 158  Protection against other hazards

Among other hazards, those related to the Low Voltage Directive (LVD) are particularly relevant.

The relationships between the ATEX Directive 2014/34/EU and other Union legislation can be found in sections §§ 231-240.

1.2.8.     Overloading of equipment

              Dangerous overloading of equipment must be prevented at the design stage by means of integrated measurement, regulation and control devices, such as over-current cut-off switches, temperature limiters, differential pressure switches, flowmeters, time-lag relays, overspeed monitors and/or similar types of monitoring devices.

§ 159  Overloading of equipment

Relevant European harmonised standards provide advice in many cases, but cannot cover all possibilities.

1.2.9.     Flameproof enclosure systems

              If parts which can ignite an explosive atmosphere are placed in an enclosure, measures must be taken to ensure that the enclosure withstands the pressure developed during an internal explosion of an explosive mixture and prevents the transmission of the explosion to the explosive atmosphere surrounding the enclosure.

§ 160  Flameproof enclosure systems

There are two specific European harmonised standards applicable to flameproof enclosure systems: EN 13463-3 Non-electrical equipment for use in potentially explosive atmospheres - Part 3: Protection by flameproof enclosure 'd' and EN 60079-1 Explosive atmospheres - Part 1: Equipment protection by flameproof enclosures ‘d’.

1.3.        Potential ignition sources

§ 161  Potential ignition sources

Paragraph 1.3 details the potential ignition sources that must be considered for ATEX equipment, according to its definition in Article 2(1).

1.3.1.     Hazards arising from different ignition sources

              Potential ignition sources such as sparks, flames, electric arcs, high surface temperatures, acoustic energy, optical radiation, electromagnetic waves and other ignition sources must not occur.

§ 162  Hazards arising from different ignition sources

These ignition sources are considered in outline in the European harmonised standard EN 1127-1 Explosive atmospheres - Explosion prevention and protection - Part 1: Basic concepts and methodology.

1.3.2.     Hazards arising from static electricity

              Electrostatic charges capable of resulting in dangerous discharges must be prevented by means of appropriate measures.

§ 163  Hazards arising from static electricity

Electrostatic discharge, as a source of ignition, is often within the control of the design of the installation, rather than the equipment, and comes within the scope of the ATEX “workplace” Directive 1999/92/EC, backed up by standards providing appropriate detailed information.

However, the design of equipment can help to mitigate such risks and appropriate requirements are detailed in European harmonised standards.

Where equipment is otherwise outside the scope of Directive 2014/34/EU, the potential for a static discharge in use does not bring it into scope.

1.3.3.     Hazards arising from stray electric and leakage currents

              Stray electric and leakage currents in conductive equipment parts which could result in, for example, the occurrence of dangerous corrosion, overheating of surfaces or sparks capable of provoking an ignition must be prevented.

§ 164  Hazards arising from stray electric and leakage currents

Stray electric currents may flow, for example, in the external frame and enclosure of a large electric motor, as a result of magnetic fluxes not being confined to the magnetic core of the stator and rotor. Such currents can become an ignition source under certain circumstances. Detailed requirements are provided in relevant European harmonised standards.

Other examples of stray electric currents would include those from galvanic corrosion protection circuits.

1.3.4.     Hazards arising from overheating

              Overheating caused by friction or impacts occurring, for example, between materials and parts in contact with each other while rotating or through the intrusion of foreign bodies must, as far as possible, be prevented at the design stage.

§ 165  Hazards arising from overheating

Relevant European harmonised standards provide guidance on this kind of hazards.

1.3.5.     Hazards arising from pressure compensation operations

              Equipment and protective systems must be so designed or fitted with integrated measuring, control and regulation devices that pressure compensations arising from them do not generate shock waves or compressions which may cause ignition.

§ 166  Hazards arising from pressure compensation operations

This essential health and safety requirement aims to prevent ATEX products to cause adverse effects such as ignition when carrying out pressure compensation operations.

1.4.        Hazards arising from external effects

1.4.1.     Equipment and protective systems must be so designed and constructed as to be capable of performing their intended function in full safety, even in changing environmental conditions and in the presence of extraneous voltages, humidity, vibrations, contamination and other external effects, taking into account the limits of the operating conditions established by the manufacturer.

1.4.2.     Equipment parts used must be appropriate to the intended mechanical and thermal stresses and capable of withstanding attack by existing or foreseeable aggressive substances.

§ 167  Hazards arising from external effects

The manufacturer’s instruction document should clearly define which potential external effects have been taken into account.

1.5.        Requirements in respect of safety-related devices

1.5.1.     Safety devices must function independently of any measurement and/or control devices required for operation.

              As far as possible, failure of a safety device must be detected sufficiently rapidly by appropriate technical means to ensure that there is only very little likelihood that dangerous situations will occur.

The fail-safe principle is to be applied in general.

              Safety-related switching must in general directly actuate the relevant control devices without intermediate software command.

1.5.2.     In the event of a safety device failure, equipment and/or protective systems shall, wherever possible, be secured.

1.5.3.     Emergency stop controls of safety devices must, as far as possible, be fitted with restart lockouts. A new start command may take effect on normal operation only after the restart lockouts have been intentionally reset.

§ 168  Requirements in respect of safety-related devices

It should be noted that the text of clause 1.5 was written before standards in the EN 61508 series (and its derivatives) were written, which expand considerably on the “fail-safe principle”. European harmonised standard EN 50495 interprets the EN 61508 requirements in the context of clause 1.5 of the EHSRs of 2014/34/EU.

See also section § 37 on safety devices, controlling devices and regulating devices as defined in Article 1(1)(b).

1.5.4.     Control and display units

              Where control and display units are used, they must be designed in accordance with ergonomic principles in order to achieve the highest possible level of operating safety with regard to the risk of explosion.

§ 169  Control and display units

In general terms, ergonomic principles are regarded as part of safety integration, or "safety by design", for equipment to be operated by users in specific working conditions. An example of an advanced application of ergonomic principles within safety integration can be found in the Machinery Directive, Annex I, 1.1.6.

The ATEX Directive 2014/34/EU makes an explicit reference to ergonomic design in this essential health and safety requirement 1.5.4. for control and display units. They must take into account these aspects in order to ensure safe operation of the related equipment.

1.5.5.     Requirements in respect of devices with a measuring function for explosion protection

              In so far as they relate to equipment used in explosive atmospheres, devices with a measuring function must be designed and constructed so that they can cope with foreseeable operating requirements and special conditions of use.

1.5.6.     Where necessary, it must be possible to check the reading accuracy and serviceability of devices with a measuring function.

1.5.7.     The design of devices with a measuring function must incorporate a safety factor which ensures that the alarm threshold lies far enough outside the explosion and/or ignition limits of the atmospheres to be registered, taking into account, in particular, the operating conditions of the installation and possible aberrations in the measuring system.

§ 170  Requirements in respect of devices with a measuring function for explosion protection

It is implicit in the wording of these clauses that the measuring device relates to measuring the concentration of gas that may be present. There is a series of European harmonised standards which provide guidance on the performance of gas detection equipment.

1.5.8.     Risks arising from software

              In the design of software-controlled equipment, protective systems and safety devices, special account must be taken of the risks arising from faults in the programme.

§ 171  Risks arising from software

Reference should be made to the various implementations of EN 61508-3 Functional safety of electrical/electronic/programmable electronic safety-related systems - Part 3: Software requirements which specifically deals with software applications in programmable safety related systems. European harmonised standard EN 50495 Safety devices required for the safe functioning of equipment with respect to explosion risks refers directly to EN 61508-3 for software consideration.

1.6.        Integration of safety requirements relating to the system

1.6.1.     Manual override must be possible in order to shut down the equipment and protective systems incorporated within automatic processes which deviate from the intended operating conditions, provided that this does not compromise safety.

1.6.2.     When the emergency shutdown system is actuated, accumulated energy must be dispersed as quickly and as safely as possible or isolated so that it no longer constitutes a hazard.

              This does not apply to electrochemically-stored energy.

§ 172  Integration of safety requirements relating to the system

Consideration must be given to arrangements for a controlled shut-down of a system, should that be necessary to avoid creating additional hazards.

1.6.3.     Hazards arising from power failure

              Where equipment and protective systems can give rise to a spread of additional risks in the event of a power failure, it must be possible to maintain them in a safe state of operation independently of the rest of the installation.

§ 173  Hazards arising from power failure

For some safety related systems, it will be necessary to provide stand-by power to ensure that the process can be safety shut down in the event of a general power failure.

Additional points for consideration could include the performance of an induction generator if it became detached from a stable grid supply and its voltage rose uncontrollably.

1.6.4.     Hazards arising from connections

              Equipment and protective systems must be fitted with suitable cable and conduit entries.

              When equipment and protective systems are intended for use in combination with other equipment and protective systems, the interface must be safe.

§ 174  Hazards arising from connections

The aim of this essential health and safety requirement is prevention of adverse effects from failure in connections (cables, conduit entries…) which can give rise to additional risks.

1.6.5.     Placing of warning devices as parts of equipment

              Where equipment or protective systems are fitted with detection or alarm devices for monitoring the occurrence of explosive atmospheres, the necessary instructions must be provided to enable them to be provided at the appropriate places.

§ 175  Placing of warning devices as parts of equipment

Adequate availability of instructions is very much related to safe operations of equipment; in this case, concerning warning devices detecting an explosive atmosphere.

See also section §151 on instructions.

2.           Supplementary requirements in respect of equipment

2.0.        Requirements applicable to equipment in equipment-group I

2.0.1.     Requirements applicable to equipment category M1 of equipment-group I

2.0.1.1.  Equipment must be so designed and constructed that sources of ignition do not become active, even in the event of rare incidents relating to equipment.

              Equipment must be equipped with means of protection such that:

              –       either, in the event of failure of one means of protection, at least an independent second means provides the requisite level of protection,

              –       or, the requisite level of protection is ensured in the event of two faults occurring independently of each other.

              Where necessary, equipment must be equipped with additional special means of protection.

              It must remain functional with an explosive atmosphere present.

2.0.1.2.  Where necessary, equipment must be so constructed that no dust can penetrate it.

2.0.1.3.  The surface temperatures of equipment parts must be kept clearly below the ignition temperature of the foreseeable air/dust mixtures in order to prevent the ignition of suspended dust.

2.0.1.4.  Equipment must be so designed that the opening of equipment parts which may be sources of ignition is possible only under non-active or intrinsically safe conditions. Where it is not possible to render equipment non-active, the manufacturer must affix a warning label to the opening part of the equipment.

              If necessary, equipment must be fitted with appropriate additional interlocking systems.

2.0.2.     Requirements applicable to equipment category M 2 of equipment-group I

2.0.2.1.  Equipment must be equipped with means of protection ensuring that sources of ignition do not become active during normal operation, even under more severe operating conditions, in particular those arising from rough handling and changing environmental conditions.

              The equipment is intended to be de-energized in the event of an explosive atmosphere.

2.0.2.2.  Equipment must be so designed that the opening of equipment parts which may be sources of ignition is possible only under non-active conditions or via appropriate interlocking systems. Where it is not possible to render equipment non-active, the manufacturer must affix a warning label to the opening part of the equipment.

2.0.2.3.  The requirements regarding explosion hazards arising from dust applicable to equipment category M 1 must be applied.

2.1.        Requirements applicable to equipment category 1 of equipment-group II

2.1.1.     Explosive atmospheres caused by gases, vapours or mists

2.1.1.1.  Equipment must be so designed and constructed that sources of ignition do not become active, even in event of rare incidents relating to equipment.

              It must be equipped with means of protection such that:

              –       either, in the event of failure of one means of protection, at least an independent second means provides the requisite level of protection,

              –       or, the requisite level of protection is ensured in the event of two faults occurring independently of each other.

2.1.1.2.  For equipment with surfaces which may heat up, measures must be taken to ensure that the stated maximum surface temperatures are not exceeded even in the most unfavourable circumstances.

              Temperature rises caused by heat build-ups and chemical reactions must also be taken into account.

2.1.1.3.  Equipment must be so designed that the opening of equipment parts which might be sources of ignition is possible only under non-active or intrinsically safe conditions. Where it is not possible to render equipment non-active, the manufacturer must affix a warning label to the opening part of the equipment.

              If necessary, equipment must be fitted with appropriate additional interlocking systems.

2.1.2.     Explosive atmospheres caused by air/dust mixtures

2.1.2.1.  Equipment must be so designed and constructed that ignition of air/dust mixtures does not occur even in the event of rare incidents relating to equipment.

It must be equipped with means of protection such that

–            either, in the event of failure of one means of protection, at least an independent second means provides the requisite level of protection,

–            or, the requisite level of protection is ensured in the event of two faults occurring independently of each other.

2.1.2.2.  Where necessary, equipment must be so designed that dust can enter or escape from the equipment only at specifically designated points.

This requirement must also be met by cable entries and connecting pieces.

2.1.2.3.  The surface temperatures of equipment parts must be kept well below the ignition temperature of the foreseeable air/dust mixtures in order to prevent the ignition of suspended dust.

2.1.2.4.  With regard to the safe opening of equipment parts, requirement 2.1.1.3 applies.

2.2.        Requirements applicable to equipment category 2 of equipment-group II

2.2.1.     Explosive atmospheres caused by gases, vapours or mists

2.2.1.1.  Equipment must be so designed and constructed as to prevent ignition sources arising, even in the event of frequently occurring disturbances or equipment operating faults, which normally have to be taken into account.

2.2.1.2.  Equipment parts must be so designed and constructed that their stated surface temperatures are not exceeded, even in the case of risks arising from abnormal situations anticipated by the manufacturer.

2.2.1.3.  Equipment must be so designed that the opening of equipment parts which might be sources of ignition is possible only under non-active conditions or via appropriate interlocking systems. Where it is not possible to render equipment non-active, the manufacturer must affix a warning label to the opening part of the equipment.

2.2.2.     Explosive atmospheres caused by air/dust mixtures

2.2.2.1.  Equipment must be designed and constructed so that ignition of air/dust mixtures is prevented, even in the event of frequently occurring disturbances or equipment operating faults which normally have to be taken into account.

2.2.2.2.  With regard to surface temperatures, requirement 2.1.2.3 applies.

2.2.2.3.  With regard to protection against dust, requirement 2.1.2.2 applies.

2.2.2.4.  With regard to the safe opening of equipment parts, requirement 2.2.1.3 applies.

2.3.        Requirements applicable to equipment category 3 of equipment-group II

2.3.1.     Explosive atmospheres caused by gases, vapours or mists

2.3.1.1.  Equipment must be so designed and constructed as to prevent foreseeable ignition sources which can occur during normal operation.

2.3.1.2.  Surface temperatures must not exceed the stated maximum surface temperatures under intended operating conditions. Higher temperatures in exceptional circumstances may be allowed only if the manufacturer adopts special additional protective measures.

2.3.2.     Explosive atmospheres caused by air/dust mixtures

2.3.2.1.  Equipment must be so designed and constructed that air/dust mixtures cannot be ignited by foreseeable ignition sources likely to exist during normal operation.

2.3.2.2.  With regard to surface temperatures, requirement 2.1.2.3 applies.

2.3.2.3.  Equipment, including cable entries and connecting pieces, must be so constructed that, taking into account the size of its particles, dust can neither develop explosive mixtures with air nor form dangerous accumulations inside the equipment.

§ 176  Supplementary requirements in respect of equipment

Section 2 of Annex II to Directive 2014/34/EU includes a list of supplementary requirements for ATEX equipment, according to equipment-groups and categories and taking into consideration different kinds of potentially explosive atmospheres caused by gases, vapours or mists, as well as possible ignition sources.

Specific guidance on technical solutions to be used to comply with these requirements for ATEX equipment is provided in the relevant European harmonised standards.

3.           Supplementary requirements in respect of protective systems

3.0.        General requirements

3.0.1.     Protective systems must be dimensioned in such a way as to reduce the effects of an explosion to a sufficient level of safety.

3.0.2.     Protective systems must be designed and capable of being positioned in such a way that explosions are prevented from spreading through dangerous chain reactions or flashover and incipient explosions do not become detonations.

3.0.3.     In the event of a power failure, protective systems must retain their capacity to function for a period sufficient to avoid a dangerous situation.

3.0.4.     Protective systems must not fail due to outside interference.

3.1.        Planning and design

3.1.1.     Characteristics of materials

              With regard to the characteristics of materials, the maximum pressure and temperature to be taken into consideration at the planning stage are the expected pressure during an explosion occurring under extreme operating conditions and the anticipated heating effect of the flame.

3.1.2.     Protective systems designed to resist or contain explosions must be capable of withstanding the shock wave produced without losing system integrity.

3.1.3.     Accessories connected to protective systems must be capable of withstanding the expected maximum explosion pressure without losing their capacity to function.

3.1.4.     The reactions caused by pressure in peripheral equipment and connected pipe-work must be taken into consideration in the planning and design of protective systems.

3.1.5.     Pressure-relief systems

              If it is likely that stresses on protective systems will exceed their structural strength, provision must be made in the design for suitable pressure-relief devices which do not endanger persons in the vicinity.

3.1.6.     Explosion suppression systems

              Explosion suppression systems must be so planned and designed that they react to an incipient explosion at the earliest possible stage in the event of an incident and counteract it to best effect, with due regard to the maximum rate of pressure increase and the maximum explosion pressure.

3.1.7.     Explosion decoupling systems

              Decoupling systems intended to disconnect specific equipment as swiftly as possible in the event of incipient explosions by means of appropriate devices must be planned and designed so as to remain proof against the transmission of internal ignition and to retain their mechanical strength under operating conditions.

3.1.8.     Protective systems must be capable of being integrated into a circuit with a suitable alarm threshold so that, if necessary, there is cessation of product feed and output and shutdown of equipment parts which can no longer function safely.

§ 177  Supplementary requirements in respect of protective systems

On definition and description of ATEX protective systems, see section § 46.

Section 3 of Annex II to Directive 2014/34/EU includes a list of supplementary requirements for ATEX protective systems.

Specific guidance on technical solutions to be used to comply with these requirements for ATEX protective systems is provided in the relevant European harmonised standards.

 

[1]      For further information on risk assessment, see EN 1127-1 Explosive atmospheres - Explosion prevention and protection - Part 1: Basic concepts and methodology. For worked examples, see EN 13463-1 Non-electrical equipment for use in potential explosive atmospheres - Part 1: Basic methods and requirements.

[2]      See as well EN 15198 Methodology for the risk assessment of non-electrical equipment and components for intended use in potentially explosive atmospheres and EN ISO 14121-1 Safety of machinery - Risk assessment - Part 1: Principles).