Statutory regulations and standards

Introduction

Areas in which there is a risk of explosion that may harm people or the environment are subject to legal or comparable rules in most countries of the world. While these rules were initially issued at the national level, they have since been replaced over the last years by regional European Directives and Standards, and in the field of standardization they have partially been replaced by international regulations.

European Directives

Already in 1976, the Council of the European Community established the prerequisite of free trade of explosion protected electrical equipment within the European Union by ratifying the “Directive on the harmonization of the laws of the member states concerning electrical equipment for use in potentially explosive atmospheres (76/117/EEC)”. This directive has since been adapted to the state of the art by means of execution and adaptation directives on electrical equipment.

Complete harmonization and extension to all types of equipment was achieved with the new Directive 94/9/EC in 1994. The Directive 99/92/EC, which regulates operation in hazardous areas and defines safety measures for the concerned personnel, was issued in 1999.

The Directive 94/9/EC (ATEX 95)

The EC Directive 94/9/EC “on the approximation of the laws of the Member States concerning equipment and protective systems intended for use in potentially explosive atmospheres” was issued in 1994 to further standardize explosion protection and make corresponding adjustments in line with a new directive approach. It specifies the requirements for explosion protected equipment and protective systems by prescribing essential health and safety requirements. It guarantees free trade within the European Community, as agreed in Article 95 (former 100 a) of the Treaty established between the European Community member states. This is also where the term generally used amongst experts, ATEX 95 or 100 a, comes from. This term is the abbreviation of the French designation for explosive atmosphere “atmosphères explosibles”.

The directive had to be implemented into national law without any changes/exceptions. E.g. it was adopted into british law by means of The Equipment and Protective Systems for Use in Potentially Explosive Atmospheres Regulations (EPS) and into German law by means of the “Explosionsschutzverordnung (ExVO)” (Regulation of Explosion Protection) as the 11th Regulation of the “Geräte- und Produktsicherkeitsgesetz (GPSG)” (Equipment and Product Safety Law).

The directive applies to all industrial potentially explosive areas including mining, and also covers dust explosion protection. The scope covers all electrical and non-electrical equipment, and protective systems.

This directive is intended for the manufacturer or the importer, and defines design, certification, production and quality assurance, marking, operating instructions, and declaration of conformity for the explosion protected equipment to be placed on the market.

Definitions

• “Equipment” means machines, apparatus, fixed or mobile devices, control components and instrumentation thereof, and detection or prevention systems which, separately or jointly, are intended for the generation, transfer, storage, measurement, control, and conversion of energy for the processing of material and which are capable of causing an explosion through their own potential sources of ignition.
  
  
• “Protective systems” is the definition for design units, which are intended to halt incipient explosions immediately and/or to limit the effective range of explosion flames and explosion pressures. Protective systems may be integrated into equipment separately and placed on the market for use as autonomous systems.
  
  
• “Components” means any item essential to the safe functioning of equipment and protective systems but with no autonomous function.
  
  
• An “explosive atmosphere” is a mixture with air, under atmospheric condition, of flammable substances in the form of gases, vapours, mists, or dusts in which, after ignition has occurred, combustion spreads to the entire unburned mixture.
  
  
• A “potentially explosive atmosphere” is an atmosphere which could become explosive due to local and operational conditions.

Scope

The directive applies to equipment and protective systems for use in potentially explosive atmospheres.

Safety devices intended for use outside potentially explosive atmospheres but required for or contributing to the safe functioning of equipment with respect to the risk of explosion are also covered by the scope of this Directive. The Directive does not include a reference to mandatory standards, whereas it specifies the essential health and safety requirements to be maintained, and which are mandatory for design and construction. Protection against other hazards (e.g. electric shock) that could be caused by this equipment, is also required as well.

Equipment categories

The manufacturer of equipment that includes their own potential ignition sources, and therefore can cause an explosion, have to ensure that the equipment undergoes an ignition hazard assessment procedure, and takes measures according to the essential safety requirements to exclude the risk of ignition. In the directive, Group II apparatus are divided into three categories with various levels of safety (for mines Group I has two categories). The required protective measures suit the required level of safety.

Categories of Group I: Surface and Underground Mining Systems in case of Dangerous Firedamp/Dust:

Categories of Group II: Other Explosive Areas:

Certification

Equipment for use in hazardous areas has to undergo the conformity assessment procedure defined in the directive prior to being placed on the market. Category 1 and M1 equipment must undergo an EC type examination carried out by a Notified Body. The same applies to electrical equipment and I.C.-engines of Category 2 and M2. For non-electrical equipment of this category, as well as for those of Category 3, the manufacturer is authorized to assess and document conformity with the requirements of the directive.

The certificates from a Notified Body are recognized throughout the European Community.

Marking

In addition to the usual data such as the name of the manufacturer, type, serial number, and electrical ratings, any data relating to explosion protection must be contained in the marking (see table 5, marking according to the 94/9/EC Directive and the standards EN 60079 ff and EN 61241 ff).

The CE marking of the equipment confirms that it is designed and manufactured in compliance with all applicable EC Directives. For example, an explosion protected luminaire marked with the CE conformity mark must comply with both the ATEX Directive as well as the “EMC Directive”.

Operating instructions

The operating instructions of the manufacturer must clearly define the intended use of the equipment by the operator. The minimum requirements for the operating instruction are amongst others:

Information on safe

• putting into servicee
• use
• assembling and dismantling
• maintenance (servicing and emergency repair)
• installation
• adjustment

If necessary, special conditions for safe use have to be specified and should include notes on possible misuse that may occur as experience has shown.

Manufacturer’s Declaration of Conformity

Equipment and systems can be placed on the market, only if marked with the CE mark and complete with operating instructions and the manufacturer’s declaration of conformity. The CE conformity marking and the written declaration of conformity confirm that the product complies with all requirements and assessment procedures specified in the EC Directives.

Marking of electrical equipment:

Marking defined by directives and standards
Manufacturer’s name or designation	Leuze electronic
Type designation (e.g.)	* 92/3 * Ex
Explosion protection marking¹	(E) Ex ia IIC T6 (E) Ex ia D21 T80°C
Marking according to CENELEC	EEx or Ex (ab 12/2004)
Types of protection	ia
Explosion groups for gases	II
Temperature class or in case of dust the max. surface temperature of apparatus	T6; T80°C
Marking according to Directive 94/9/EC	II 2 G D
EU distinguishing mark
Equipment group	II
Equipment category	1, 2 oder 3
G: Gases, vapours or mists; D: dusts	G, D
Testing authority, number of certificate	DMT 03 ATEX E 029
CE mark, number of the auditing and supervising authority	0158
EElectrical ratings	V, A, W, Hz
Ambient temperature, if other than –20 °C…+40 °C	Ta ≤ +50 °C

¹ With an ... X if reference special conditions for use.

The Directive 99/92/EC

In addition to the 94/9/EC Directive, which regulates how explosion protected equipment and protective systems are placed on the market and the design, construction and quality requirements to be met by them, the 99/92/EC Directive stating “Minimum requirements for improving the health and safety protection of worker potentially at risk from explosive atmospheres” refers to the operation of potentially explosive installations, and is therefore intended for the employer. This directive contains only minimum requirements. When implementing it into national law, the single states can adopt further regulations. This was done when implementing it into British law by “The Dangerous Substances and Explosive Atmospheres Regulations (DSEAR)” and into German law by the “Betriebssicherheitsverordnung (BetrSichV)”, the German regulation on Industrial Safety and Health Protection, which in addition to this directive, takes into consideration further European directives on safety on work. Comparable regulations are found in other European countries.

According to the 99/92/EC Directive, it is the duty of the employer to verify where there is a risk of explosion, classify the hazardous areas into zones accordingly, and document all measures taken to protect the personnel in the explosion protection document.

Assessment of explosion risks

When assessing the risks of explosion, the following factors are to be taken into account:

• the likelihood that explosive atmospheres will occur and their persistence
• the likelihood that ignition sources, including electrostatic discharges, will be present and become active and effective
• the installations, substances used, processes, and their possible interactions
• the scale of the anticipated effects

Zone Classification

The employer has to classify the areas in which explosive atmospheres may be present into zones, and to ensure that the minimum organisational and technical requirements of the Directive are observed.

Zone 0

A place in which an explosive atmosphere consisting of a mixture with air of flammable substances in the form of gas, vapour or mist is present continuously or for long periods or frequently.

Zone 1

A place in which an explosive atmosphere consisting of a mixture with air or flammable substances in the form of gas, vapour or mist is likely to occur in normal operation occasionally.

Zone 2

A place in which an explosive atmosphere consisting of a mixture with air of flammable substances in the form of gas, vapour or mist is not likely to occur in normal operation but, if it does occur, will persist for a short period only.

Zone 20

A place in which an explosive atmosphere in the form of a cloud of combustable dust in air is present continously, or for long periods or frequently.

Zone 21

A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is likely to occur in normal operation occasionally.

Zone 22

A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is not likely to occur in normal operation but, if it does occur, will persist for a short period only.

The Table contains an overview of the zones and allocation of equipment according to the category.

Zones and allocation of equipment according to the category:

Explosion protection document

An explosion protection document has to be generated, which contains at least the following information:

• assessment of the explosion risk
• protective measures taken
• zone classification
• observance of minimum requirements. These are divided into organisational measures (instruction of workers, etc.) and technical measures (explosion protection measures).

Standards

The European Standards EN 50014 - EN 50020 on electrical equipment were issued in 1978 and replaced the national standards for this equipment valid up until then Europe-wide. In addition to the standards for electrical equipment published by the CENELEC, standards for non-electrical explosion-protected equipment have since been developed by the CEN.

According to an agreement between the European Committee for Electrotechnical Standardization CENELEC and the International Electrotechnical Commission IEC, the European standards for electrical equipment have been adopted unchanged by the IEC for several years. The European Standard series EN 50014, which defines the requirements on equipment to be used in explosive gas atmospheres, will be gradually replaced by the European Standards series EN 60079. These standards have been issued as VDE 0170 in Germany.

The requirements on types of protection for areas where combustible dust may occur are specified in the standard series IEC 61241. In Europe, these standards replace the existing series EN 50281. Since many requirements are identical to the standards for explosive gas atmospheres, both standard series will be summarized in the series IEC or EN 60079.

Electrical Apparatus for Explosive Gas Atmospheres:

Electrical Apparatus for Use in the Presence of Combustible Dust: