ATEX requirements in the workplace

There is new legislation in place to deal with Explosive Atmospheres in the Irish workplace as a result of a new EU Directive. They are mentioned in Part 8 of the 2007 Safety, Health & Welfare at Work Regulations. There is also some information provided in Schedule 10 of the regulations.

Explosion protection is of particular importance to safety as explosions endanger the lives and health of workers as a result of the uncontrolled effects of flame and pressure, the presence of noxious reaction products, and consumption of the oxygen in the ambient air, which workers breathe.

For this reason, the establishment of a coherent strategy for the prevention of explosions requires that organisational measures be taken at the workplace. It must be emphasised that compliance with the minimum requirements set out in the Directive does not guarantee compliance with the appropriate national laws. The Directive was adopted under Article 137 of the Treaty establishing the European Community, and this Article expressly does not prevent Member States from maintaining or introducing more stringent protective measures compatible with the Treaty.

Its aim is thus to enable the employer, particularly Small and Medium Enterprises (SME's), to perform the following explosion protection functions:

• To identify hazards and assess the risks;
• To lay down specific measures to safeguard the safety and health of workers at risk from explosive atmospheres;
• To ensure a safe working environment and appropriate surveillance during the presence of Workers in accordance with the risk assessment;
• To take the necessary steps and make the necessary arrangements for coordination when several firms are operating at the same workplace;
• To produce an explosion protection document.

Overview

Gases, vapours, mists and dusts can all form explosive atmospheres with air. Hazardous area classification is used to identify places where, because of the potential for an explosive atmosphere, special precautions over sources of ignition are needed to prevent fires and explosions.

Hazardous area classification should be carried out as an integral part of the risk assessment to identify places (or areas) where controls over ignition sources are needed (hazardous places) and also those places where they are not (non hazardous places). Hazardous places are further classified in Zones which distinguish between places that have a high chance of an explosive atmosphere occurring, and those places where an explosive atmosphere may only occur occasionally or in abnormal circumstances. The definitions of the Zones (which are included in DSEAR) also recognise that the chance of a fire or explosion depends on the likelihood of an explosive atmosphere occurring at the same time as an ignition source becomes active.

DSEAR defines a place where an explosive atmosphere may occur in quantities that require special precautions to protect the health and safety of workers as hazardous. A place where an explosive atmosphere is not expected to occur in quantities that require such special precautions is deemed to be non-hazardous. For these purposes “special precautions” means precautions to control potential ignition sources within a hazardous area, particularly in relation to the construction, installation and use of equipment.

The term “not expected to occur in such quantities” means that employers should consider the likelihood of releases of explosive atmospheres as well as the potential quantity of such releases when considering area classification.

So if a release is extremely unlikely to occur and/or if the quantities released are small, it may not be necessary to classify the area as hazardous. For example, if a dangerous substance is being carried through a seamless pipe, and that pipe has been properly installed and maintained, it is extremely unlikely that the substance will be released. An explosive atmosphere would not be expected to occur from this source and the area surrounding the pipe would be non-hazardous.

A spillage from a small bottle of solvent would release so little flammable material that no special precautions are needed other than the general control of ignition sources (for example, no smoking) and cleaning and disposing of the spillage. It would not be classified as a hazardous area. When considering whether hazardous area classification is necessary for “small” quantities of dangerous substances the actual circumstances of use and any specific industry guidance should also be taken into account.

Dangerous substances in small pre-packaged containers for sale, display, etc. in retail premises would not normally ("normal" is intended to ensure that a typical situations such as a poorly ventilated basement in a Shop etc. where aerosols or other flammables are present remains subject to a hazardous area classification study) require the area to be classified as hazardous.

However we would expect a hazardous area classification to be carried out for pre-packaged containers held in large quantities e.g. in warehouses. Procedures to clean up and dispose of any spillage/release and to control ignition sources in the event of such a release would be needed.

Some Examples of explosion hazards include the Chemical industry, Landfill tips and Civil Engineering, Waste disposal companies, Wood-working industry, Paint-spraying operations, Agriculture, to name but a few.

Zoning of hazardous places

A hazardous place is a place in which an explosive atmosphere may occur in such quantities as to require special precautions to protect workers against explosion hazards. Such a quantity is termed a hazardous explosive atmosphere. As a basis for determining the extent of protective measures, any remaining hazardous places must be classified in terms of zones according to the likelihood of occurrence of such atmospheres. They regulations refer to zoning for dusts, mists, vapours, gases, etc.

Requirements for work equipment

The employer must ensure that work equipment and all installation materials are suitable for use in hazardous places. In doing so, he must take account of the possible ambient conditions at the workplace in question. The work equipment must be so assembled, installed and operated that it cannot cause an explosion.

Marking of hazardous places

Directive 1999/92/EC stipulates that the points of entry to places where hazardous explosive atmospheres may occur in such quantities as to endanger the health and safety of workers must where necessary be marked by the employer with the following warning sign:

Warning sign for places where explosive atmospheres may occur must contain specific characteristics:

Distinctive features: triangular shape, black letters on a yellow background with black edging (the yellow part to take up at least 50 % of the area of the sign).

Such marking is required e.g. for rooms or areas in which a hazardous explosive atmosphere may arise (such as rooms or fenced enclosures where flammable liquids are stored). On the other hand, there is no point in marking an item of plant which is fully protected by mitigation measures. If the hazardous place is not the whole space concerned, but only part of it, that part may be marked by yellow/black diagonal stripes e.g. on the floor.

Other details may be added to the warning sign, indicating e.g. the nature and frequency of occurrence of the hazardous explosive atmosphere (substance and zone). It may be desirable to place other warning signs in accordance with 92/58/EEC, for example forbidding smoking, etc. Workers' attention must be drawn to the sign and its meaning in the course of their training.