Everything maintenance professionals need to know about ATEX zones

ATEX zones are classified based on the likelihood and frequency of an explosive atmosphere. Below is an overview of the primary zones:

For Gas Explosion Hazards

• Zone 0: An explosive atmosphere is continuously or frequently present.
  Example: Inside a storage tank containing flammable liquid.
• Zone 1: An explosive atmosphere is likely during normal operating conditions.
  Example: Around pumps or valves in a chemical plant.
• Zone 2: An explosive atmosphere is rarely and only briefly present.
  Example: Near pipeline leaks that are quickly repaired.

For Dust Explosion Hazards

• Zone 20: An explosive dust cloud is continuously or frequently present.
• Zone 21: An explosive dust cloud is likely during normal operating conditions.
• Zone 22: An explosive dust cloud is rarely and only briefly present.

Examples of ATEX zones in companies

• Battery charging areas: Places where acid batteries are charged, for example in warehouses, are often classified as Zone 1 or Zone 2 due to the release of hydrogen gas.
• Gas storage areas: Storage sites for industrial gases such as LPG or oxygen fall under Zone 1 or Zone 2, depending on ventilation and presence of ignition sources.
• Storage areas for organic substances: Silos or storage areas for substances such as grain, wood dust or sugar are often classified as Zone 20 or Zone 21 due to the risk of explosive dust clouds.
• Chemical plants: Reaction vessels, storage tanks and pipes containing volatile chemicals often fall under Zone 0 or Zone 1.
• Food industry: Storage silos for cereals or powdered ingredients such as flour are often classified as Zone 20 or Zone 21.
• Petrol stations: The area around filling guns and underground fuel tanks is usually classified as Zone 1 or Zone 2.
• Textile industry: Areas where fine fibres or dust particles are present, such as when spinning cotton, may fall under Zone 21 or Zone 22.
• Waste processing plants: Plants processing organic waste or fermenting materials are often classified in Zone 1 because of the formation of biogas.

According to the ATEX 153 directive, employers are obliged to prepare an explosion protection document (EPD). This document must demonstrate that the risk of explosions has been analysed and that appropriate preventive and protective measures have been taken. The EPD includes:

• An overview of the ATEX zones within the plant: Where are potential explosive atmospheres located?
• A detailed zoning plan: This describes the exact classification of zones (Zone 0, 1, 2, 20, 21, 22) on the shop floor and the frequency with which explosion hazards may occur.
• An analysis of ignition sources: Both mechanical and electrical equipment is assessed for potential risks.
• Description of organisational and technical measures: Such as staff training, inspection programmes, and use of ATEX-certified equipment.

The EPD should be kept up to date and updated when changes in processes or equipment occur. Maintenance professionals play a key role in keeping the EPD up to date by providing data, inspection reports, and risk assessments.

A zoning plan is a visual and detailed map of the shop floor showing where explosion hazards may be present and how often they may occur. This plan is an essential part of the explosion protection document and serves several purposes.

1. Identification of flammable substances: Determine which gases, vapours or dusts are present and their properties.
2. Analysis of processes: Evaluate which areas are at risk of forming explosive atmospheres.
3. Zoning: Assign zones based on probability and duration of explosion hazard (e.g. Zone 0, 1, 2, 20, 21, 22).
4. Visualisation: Create a clear map showing zones and hazards, including equipment specifically designed for use in those zones.

Zoning plans may be prepared by the company, but should always be verified by an external technical control service. Zoning plans should be reviewed and updated regularly, especially after process changes, the introduction of new equipment or after incidents.

1. Equipment selection

Maintenance professionals must ensure that all equipment used is suitable for the specific ATEX zone. Equipment is classified into various groups and categories indicating the zones in which it can be safely used.
Example: Equipment used in Zone 1 must meet stricter requirements than equipment for Zone 2.

2. Inspection and maintenance

Regular maintenance is essential to prevent failures that increase explosion risks. This includes:

• Checking seals and connections for leaks (with inert gas).
• Inspections of electrical installations to prevent sparking. The installation should be inspected annually by an external service.
• Cleaning to avoid accumulation of dust layers.

3. Competence and training

Working in ATEX zones requires specific knowledge and skills. Training on explosion safety helps professionals understand the risks and implement safe work practices.

New technologies are playing an increasing role in improving safety and efficiency in ATEX zones. Consider:

• Heat cameras: Heat cameras are valuable tools in ATEX zones. They make it possible to detect temperature differences without direct contact with equipment, which helps to identify overheating or defects at an early stage. Only ATEX-certified heat cameras should be used in zoned areas.
• Ex-certified equipment: Products that are ATEX-certified have an official ‘Ex’ badge. Equipment that does not have it can be an ignition source.
• Predictive maintenance tools: These technologies use IoT sensors and AI to detect potential defects early.
• Drones and robots: For inspections in hard-to-reach or hazardous areas, reducing risks to personnel.

Best Practices for Safe Maintenance in ATEX Zones

ATEX zones pose specific challenges for maintenance professionals. By thoroughly understanding regulations, using appropriate equipment, and performing proactive inspections and maintenance, risks can be effectively managed. Investing in training and modern technologies is crucial to ensuring safety and efficiency.