Explosive atmospheres directive

HS(Rjl5 Administrative guidance on the European Community Explosive Atmospheres Directives (76/... 

The Order imposes a number of specific duties in relation to the fire precautions to be taken. The Order provides for the enforcement of the Order, appeals, offences and connected matters. The Order also gives effect in England and Wales to parts of a number of EC Directives including the Framework, Workplace, Chemical Agents and Explosive Atmospheres Directives. 

There is a transitional period leading up to 1 July 2003 during which manufacturers can choose to satisfy the provisions of the new Regulations, or comply with the existing Explosive Atmospheres Directives, or comply with the general provisions of the HSW Act, section 6. 

Protection of workers potentially at risk from explosive atmospheres Directive... 

Note that, under the Protection of Workers Potentially at Risk from Explosive Atmospheres Directive, there is an attempt to align the zone definitions for gases and dust clouds according to the risk of the hazard being present. Thus, there are three new zone definitions relating to dust ... 

Certain types of equipment are specifically excluded from the scope of the directive. It is self-evident that equipment which is already regulated at Union level with respect to the pressure risk by other directives had to be excluded. That is the case with simple pressure vessels, transportable pressure equipment, aerosols and motor vehicles. Other equipment, such as carbonated drink containers or radiators and piping for hot water systems are excluded from the scope because of the limited risk involved. Also excluded are products which are subject to a minor pressure risk which are covered by the directives on machinery, lifts, low voltage, medical devices, gas appliances and on explosive atmospheres. A further and last group of exclusions refers to equipment which presents a significant pressure risk, but for which neither the free circulation aspect nor the safety aspect necessitated their inclusion. 

For many years the pneumatic controller was preferred to its electronic counterpart due to its simplicity, its general ruggedness in the process environment, and the fact that its output could be used to operate directly the diaphragm of a pneumatic control valve. Although now largely superseded by software or hard wired electronic equivalents, pneumatic controllers are still employed in special circumstances, e.g. in explosive atmospheres. Furthermore, substantial numbers of pneumatic controllers can be found on older plant and thus an understanding of their principles of operation is necessary. 

The main issue here as regards to SRVs is the Guidelines on the Application of Directive 94/9/EC of 23 March 1994 on the approximation of the laws of the Member States concerning equipment and protective systems intended for use in potentially Explosive Atmospheres Second edition - July 2005. The paragraph affecting SRVs is the section on what is called simple products (including simple valves), which remains in the guidelines and reads as follows ... 

Surfaces of electrical apparatus or components exposed to an explosive atmosphere can start a chemical reaction, if the surface temperature exceeds a certain limit, which depends on surface shape, area, material and flow conditions (direction, velocity) of a specified surrounding atmosphere. 

One of the primary contents of the Treaties of the European Community (EC) is the elimination of trade barriers for technical equipment. These barriers have been based on different technical standards (and their legislation) in the member states of the EC. Referring to article 100 of the Treaties of the EC, some directives have been issued in order to harmonize the standardization for technical products (explosion protected electrical apparatus and systems, elevators). These directives describe precisely the technical requirements and list the relevant standards, in the field of explosion protection CENELEC Standards exclusively. Directive 82/130/EEC refers to mines endangered by firedamp and/or combustible dusts, and Directive 76/117/EEC covers areas hazardous due to potentially explosive atmospheres. The member states of the EC shall transform these directives into their national legislation within 18 months. 

To enable an effective purging, the protective gas flow direction during purging should support the escape of the unwanted atmosphere by an appropriate combination of purging flow direction and gas density (the potentially explosive atmosphere, i.e. a gas-air mixture, compared with the protective gas) ... 

Directive concerning the avoidance of risks due to explosive atmospheres (aided by a collection of examples)... 

By this directive, which is the 15th individual directive according to article 16 of framework directive 89/391/EEC, minimum requirements for the protection of workers against explosive atmospheres at workplaces have been established [6-22]. It complements the earher EU directive 94/9/EC, which laid down provisions and specifications for devices and protection systems for use in explosive atmospheres [6-23]. In the case of an explosion, fife and health of workers are severely endangered as a result of uncontrolled effects of flame and pressure, the presence of noxious reaction products, and the consumption of the oxygen in the ambient air which workers need to breathe. Explosive atmosphere means a mixture with air, under atmospheric conditions, of flammable substances in the form of gases, vapors, mists, or dusts, in which, after ignition has occurred, combustion spreads to the entire unburned mixture. 

Furthermore, the employer is required, to use or to provide only work equipment and protective devices which are in compliance with the European Community provisions on design, manufacture, and supply with respect to health and safety. This includes consistency with the provisions of the EU directive 94/9/EC [6-23] dealing with equipment and protecting systems intended for use in potentially explosive atmospheres, and consistency with the existing European technical standards. 

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 1999/92/EC on minimum requirements for improving the safety and health protection of workers potentially at risk from explosive atmospheres, O.J. L023,28.1.2000, p. 57. 

Directive 1994/94/EC of the European Parliament and the Council of 23 March 1994 on the approximation of the laws of Members of the States concerning equipment and protective systems intended for use in potentially explosive atmospheres. 

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. 

These regulations illustrate a trend that is occurring in safety legislation, which is now starting to move from a prescriptive approach with definitions of what has to be done in specific situations to a more risk-based approach where the precautions and actions taken are left to the individual user provided they meet certain risk-based criteria. A proposed European Directive concerning minimum requirements for improving the safety and health of workers potentially at risk from explosive atmospheres extends this concept to all work places where flammable atmospheres may be formed. When adopted, this will require all employers to carry out a hazard assessment to identify whether a flammable atmosphere is likely to exist and, where so, to demonstrate that appropriate technical, organisational and other measures appropriate to the nature of the operation have been taken to minimise the risk. 

Legislation concerning flammable solvents is not limited to situations where such solvents are being handled. In addition, equipment manufacturers who supply equipment for use in such situations are also controlled by an extensive array of regulations. These requirements are illustrated by the recent European Directive concerning equipment and protective systems intended for use in potentially explosive atmospheres [26]. This sets out essential safety requirements which will have to be met by equipment manufacturers before a product can be placed on the market in the future. 

EC Directive 94/9/EC (1994) Equipment and protective systems intended for use in potentially explosive atmospheres. 

The European directives for EC marking are intended for a wide range of products (industrial machines, explosives for civil use, toys...), with particular uses (explosive atmospheres) or with specific risks (low tension, pressurized equipment, electromagnetic compatibility). The conformity assessment of a product is consequently complex because it is necessary to ensure product conformity in all applicable directives. 

Since July 2003, manufacturers can only market apparatus or equipment compliant with the requhe-ments of directive 94/9/CE if it is intended for use in explosive atmospheres formed by gases, vapours or dust. 

However, Machinery directive 98/37/CE (revised by directive 2006/42/CE) defines all the risks associated with a machine, including risks due to explosive atmospheres. 

The Directive on Equipment and Protective Systems Intended for use in Potentially Explosive Atmospheres (94/9/EC) came into force on March 1, 1996. All... 

Internal Control of Production Manufacturers shall prepare technical documentations that allow the conformity of a product to be assessed. In some cases a copy of these documentations shall be presented to a notified body for review. Here it is important to note that there are two categories of CE certifications, namely, CE marking with or without identification number, as shown in Fig. X/3.2.2-1. Surface temperature details are available in Table X/3.2.1-4. There is another ATEX directive (99/92/EC), which is known as the ATEX workplace directive or ATEX 137. This is meant for the duty of employees to minimize the risk from explosive atmospheres. See also Clause 3.2.3. 

In line with the directive, employers need to classify into zones the areas in which explosive atmospheres may be present, and to ensure that the directive is observed. In the zone system there are clear divisions between gas and dust. For gas systems, zones are classified as zone 0, 1, and 2, whereas for dust they are designated as zone 20, 21, and 22, as detailed in Table X/3.23-1. 

Decision about extent of zone, that is, distance from source (in all directions) up to which an explosive atmosphere exists before the material is dispersed. Rate of release (velocity, size, and geometry of sources), ventilation, and relative density of flammable material (mainly gas) are important considerations. 

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... 

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