ATEX Potentially Explosive Atmospheres

Substances having a calorific value which is different from that of the calibration gas caimot be determined quantitatively. Usually, the true concentration is higher than that found by FID. In analogy to PID detectors, an exact concentration analysis can be performed for a known composition after calibration. Despite the high combustion temperatures, FID instruments are commercially available for use in potentially explosive atmospheres, meeting the requirements according to EU directive 99/92/EC (ATEX 2002) [6-22]. 

Directive 94/9/EC (ATEX 95) to approximate the laws of the Member States concerning equipment and protective systems intended for use in potentially explosive atmospheres governs requirements for products intended for the use in explosion risk areas. Directive 1999/92/EC (ATEX 137) on minimum requirements for improving the safety and health protection of workers potentially at risk from explosive atmospheres regulates the minimum requirements for explosion protection at work places and for the safe use of products. The ATEX 95 therefore deals with the properties of the products to be used in explosion risk areas while ATEX 137 regulates their operation and other operational measures for explosion protection. 

As discussed earlier, the European Union has adopted two harmonized directives on health and safety, known as ATEX 94/9/EC (also ATEX 95) and ATEX 99/92/EC (also ATEX 137). ATEX Directive 94/9/EC focuses on the essential safety requirements (SRSs) for products and protective systems for use in potentially explosive atmospheres and the respective conformity assessment procedures. ATEX Directive... 

EC, on the other hand, looks after the minimum health and safety requirements for workplaces with a potentially explosive atmosphere. In ATEX 95, entire systems have been divided into groups and categories as already discussed. In Directive 137, workplace area has been divided into zones. Use of various categories of equipment in various zones is elaborated in Table X/3.2.3-3. The basic purposes of each of these directives are elaborated in Fig. X/3.3.3-1. This figure also shows the correlation between the two directives so readers can have better understanding of the directives with their distinctive features. 

The use of electrical equipment in potentially flammable atmospheres should be avoided as far as possible. However, there will be many cases where electrical equipment must be used and, in these cases, the standards for the construction of the equipment should comply with the Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations (known as ATEX) and details on the classification or zoning of areas are published by the British Standards Institution and the Health and Safety Executive. 

In 1994 European parliament issued the ATEX directive (145) on the approximation of the laws of the member states, concerning equipment and protective systems intended for use in potentially explosive atmospheres. The scope, these regulations specifically require protective systems, intended to halt incipient explosions immediately... 

In Europe, all equipment used in a potentially explosive atmosphere needs to be compliant with the ATEX guidelines (34). 

Two important EU directives, referred to as the ATEX directives (ATEX 100a and ATEX 137), have been introduced concerning equipment and installations in potentially explosive atmospheres. One is an equipment directive covering tiie design and manufacture of equipment for use in hazardous areas the otiier is a users directive dealing with the use and operation of equipment in hazardous areas. These direchves apply to non-electrical as well as to electrical equipment. All equipment and components intended for use in potentially explosive atmospheres (gases, vapours, mists or dusts) need to comply with the requirements of these directives. Certification will be xmdertaken throughout the EU to common rules and procedures. 

ATEX From EU directive on working in potentially explosive atmospheres... 

The title of this chapter refers to the requirements on vacuum pumps intended for use in potentially explosive atmospheres which result from the European Directives 94/9/EC [1] (ATEX 95 i) and 99/92/EC [2] (ATEX 137 ). 

The Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations 1996 were made by the Secretary of State for Trade and Industry, coming into force on 1 March 1996. They implement the provisions of Directive 94/9/EC, the so-called ATEX Directive, and they will be referred to here as the ATEX Regulations. 

As a further complication, the ATEX Directive, enacted in the UK as The Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations 1996 (see Chapter 7) introduced the concept of equipment categories, which will have to be adopted at the end of the transition phase in 2003. In very broad terms these categories are ... 

ATEX An EU directive that describes the work that maybe safely carried out in an explosive atmosphere. The areas or zones in a process plant are classified according to the type of hazards, the location, and size, and the likelihood of an explosion. It is applied to mining operations, offshore processing, petrochemical plants, and flour mills, where potentially explosive atmospheres may exist. The name is derived from the French title for the EU directive Appareik et systemes de protection pour les atmospheres explosibles. 

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