ATEX EXPLOSIVE ATMOSPHERE

Atex

Making Sense of the ATEX Directive

The complexity of meeting the ATEX requirements and conforming to their standards is not an easy task! This article is not meant as a standalone or to be used in isolation, but as a starting point. Exact information on any actual precise requirements should be fully researched separately.

This new European directive, which came into effect from 1st July 2003, deals with electrical, mechanical, hydraulic or pneumatic equipment in areas exposed to explosive atmosphere. Explosive atmospheres consist of air and some sort of combustible material such as gas, dust or vapour.

What does ATEX stand for?

ATEX (from the French ATmosphere EXplosive or Areas with Explosive Atmospheres), refers to two new EU directives relating to the danger of explosion within different areas. The first ATEX directive (94/9/EC) deals with the requirements pertaining to equipment used in areas where there is a danger of explosion. The manufacturer has to fulfil the requirements and mark his products with the relevant approval. The second ATEX directive, (99/92/EC) deals with the minimum health and safety requirements that the user has to fulfil, when working within areas where there is a danger of explosion.

How is an explosive atmosphere categorised?

An explosive atmosphere is an atmosphere that develops explosively because of changing surroundings or as a consequence of use. An explosive atmosphere consists of air and combustive material such as gases, vapours or dust in which the explosion could spread after ignition. Typical production sites where combustible dust is of major concern is in, for example, the handling of cereals, animal feed, paper, wood, chemicals, plastics and coals.

What types of equipment does the ATEX directive cover?

The Directive covers a surprisingly large range of equipment and industrial applications. Broadly speaking these must comply in the following areas:

Safety equipment and safety systems exposed to explosive gases or dust.

Safety, control and adjustment devices, which ensure a safe operation of production material and control equipment.

Electrical, mechanical, hydraulic and pneumatic equipment including pumps and electric motors.

What happened on 1 July 2003?

Companies that produce, use or distribute this kind of equipment must comply with the basic health and safety requirements contained within the ATEX directive.

The ATEX directive does not have retrospective implications. However, pre-existing products maybe be subject to analysis. In case of defects, (wear etc) the old products must be replaced with equipment that complies with the ATEX directive. In addition, products that are specifically made for use in areas with the high explosion risk should only be marketed when they fully comply with the ATEX directive.

The safety requirements within the ATEX directive implies that pumps have to carry a clear indication of which equipment group and category, they belong to, and in what areas they can be used.

What are the implications for with the equipment user?

To prevent explosion, the equipment user is required to:

Take all necessary technical and organisational precautions.

Make a complete estimate of any explosion risk.

Divide potential explosive risk areas into zones.

Indicate the danger zones clearly.

How should explosive atmosphere zones be divided?

The ATEX directive distinguishes between two types of explosive atmospheres: gas and dust. Areas within these two kinds of explosive atmospheres are each divided into three sub-zones. Although the zones characteristics are identical for both gas and dust, their numbering is different. Zone 0, 1 and 2 refer to gas and Zone 20, 21 and 22 refer to dust.

Zone 0 / 20: Constant danger

Permanent presence of explosive gasses or combustive dust. Minimum of Category 1 equipment.

Zone 1 / 21: Potential danger

Occasional presence of explosive gasses or combustible dust during normal duty. Minimum of Category 2 equipment.

Zone 2 / 22: Minor danger

Presence of explosive gasses or combustible dust is not likely to occur or only for a shorter period of time. Minimum of Category 3 equipment.

Grundfos manufactures pumps, with motors in both Categories 2 and 3. The illustration above (See Figure 1) shows the division of an area into zones dependant on the level of danger from explosion. In each of the three different zones, only a certain category of equipment, in this case, motors and pumps, can be used due to the danger of explosion.

NB It is the responsibility of the equipment user, to define whether a zone is to be considered hazardous within the regulations as stated in the ATEX directive. If the user has any doubts about the definition of hazardous areas, he should take advise from a competent/recognised inspectorate.

How to ensure compliance with the ATEX directive?

Equipment and zones have to comply with the ATEX directive. The CE marking is proof that the equipment is manufactured according to the basic requirements and assessment procedures that apply to every EU member state.

Who is responsible for meeting the requirements in ATEX directive?

Depending on whether you are the equipment manufacturer, user or service mechanic there are certain safety requirements that you must comply to.

The Manufacturer:

Is exclusively responsible for producing equipment that meets the requirement stated in the EU directive.

The User:

It is the responsibility of the equipment user to inform the seller of what kind of equipment he needs, as to:

Category, e.g. 2G

Temperature, e.g. 125°C

2G/3G motor protection, e.g. Eexe II T3

In addition, the equipment user has to use the product according to the pre-defined zones and therefore must take any possible risks into account. Likewise, the equipment user has a responsibility to ensure the equipment runs safely through continuous maintenance. As of July 2003, installations must meet the requirements stated in the ATEX directive. If the equipment user is also the manufacturer, the user must fulfil all the requirements for both.

The Service Mechanic:

Service mechanics are not covered by the directive 94/9/EC. However, service mechanics have to make sure that the work they conduct meets the safety demands that apply for products and equipment, so that all safety issues are fully complied with. Notified bodies such as KEMA and PTB have the authority to issue qualification certificates for service mechanics as proof of their knowledge in this field.

The requirements of the ATEX directive are not entirely new to electric motors. Previously, they were placed under the IEC60079 standard and under local standards around the world. The ATEX directive includes references to EN standards that contain the same requirements as the IEC60079 standard. The IEC60079 standard still applies to electric motors in other parts of the world.

Where can I get further information?

Additional information can be requested from the appropriate regulatory body. General information can be found on http://www.europa.eu.int.

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