The basics of explosion protection - STAHL - #13

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3.2.2 The Directive 99/92/EC

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.

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.

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.

R.STAHL explosion protection