In brief
In workplaces where flammable gases, vapours, mists or dusts are present and an explosive atmosphere may form, the employer prepares an explosion protection document before work begins. The document puts in writing the explosion risk, the zone classification (Zones 0, 1, 2 and 20, 21, 22), the suitability of equipment in each zone and the measures taken; it is updated after significant changes. At least category 2 equipment is used in Zone 1 and at least category 3 equipment in Zone 2.
Which workplaces need an explosion protection document?
The explosion protection document is the key document prepared by the employer in workplaces within the scope of the Regulation on the Protection of Employees from the Hazards of Explosive Atmospheres. The regulation applies to workplaces within the scope of Law No. 6331 where an explosive atmosphere may form. In Europe, this regulation corresponds to Directive 1999/92/EC and is commonly referred to in practice simply as “ATEX”.
The regulation defines an explosive atmosphere as a mixture with air, under atmospheric conditions, of flammable substances in the form of gases, vapours, mists or dusts in which, after ignition has occurred, combustion spreads to the entire unburned mixture. Typical areas falling under this definition are:
- Paint booths, and mixing and filling areas where solvents and thinners are used
- LPG, natural gas and other flammable gas installations, tanks and filling points
- Flammable liquid stores and waste solvent areas
- Departments where flour, sugar, wood, plastic and metal dust is generated or conveyed; filters, cyclones and silos
- Enclosed areas where gas can accumulate, such as battery charging areas
The paint lines of Bursa’s automotive supply industry, textile dye houses, the varnish and lacquer sections of furniture workshops, and chemical and plastics businesses are examples we often encounter within this scope. The regulation excludes some activities from its scope, for example the manufacture and storage of explosives, mineral extraction and areas used directly for the medical treatment of patients.
Prevention first: the regulation’s order of priority
Art. 5 of the regulation requires the employer to take technical and organisational measures in the following order of priority:
- Preventing the formation of an explosive atmosphere: closed systems, adequate ventilation, replacing the flammable substance with a less hazardous one, preventing dust accumulation.
- If formation cannot be prevented, preventing ignition: control of ignition sources, suitable equipment, earthing against static electricity, hot work control.
- Reducing the harmful effects of an explosion: explosion venting panels, suppression systems, separation and isolation.
This order matters. Keeping solvent vapour in a paint booth below the limit through ventilation comes before equipping the booth with Ex equipment; both are applied together, but the former is the main measure. We have separately explained how to read the properties of a chemical from its safety data sheet.
Assessing explosion risk
Explosion risk is part of the workplace’s general risk assessment, but it requires a separate depth. Under Art. 6 of the regulation, the employer takes into account:
- The likelihood that an explosive atmosphere will form and its persistence
- The presence of ignition sources, including static electricity, and the likelihood that they will become active
- The workplace, the substances used, the processes and their possible interactions
- The scale of the effects of a possible explosion
Other areas connected to places where explosive atmospheres may form are assessed as a whole. For example, a solvent store and the filling room connected to it are considered together, not separately.
ATEX zone classification: Zones 0, 1, 2 and 20, 21, 22
Annex 1 of the regulation divides hazardous areas into zones according to the frequency and duration of the occurrence of explosive atmospheres. Zones 0, 1 and 2 are used for gases, vapours and mists; Zones 20, 21 and 22 for combustible dust.
| Zone | Atmosphere | Definition (summary) | Typical example |
|---|---|---|---|
| Zone 0 | Gas, vapour, mist | Explosive atmosphere present continuously, for long periods or frequently | The interior of a solvent tank |
| Zone 1 | Gas, vapour, mist | Likely to occur occasionally in normal operation | Around a filling opening, near an open mixing vessel |
| Zone 2 | Gas, vapour, mist | Not expected in normal operation; if it occurs, only for a short period | Around flanges and valves, a well-ventilated store |
| Zone 20 | Combustible dust | Dust cloud present continuously, for long periods or frequently | Inside a silo, cyclone or filter |
| Zone 21 | Combustible dust | Likely to occur occasionally in normal operation | Around a bag emptying and feeding point |
| Zone 22 | Combustible dust | Not expected in normal operation; if it occurs, only for a short period | Around machines where dust can accumulate |
The examples are typical situations; the exact zone of an area is determined by calculation, taking into account release sources, ventilation and the properties of the substance. In practice, TS EN 60079-10-1 is used for gas and TS EN 60079-10-2 for dust. Annex 1 also requires layers, deposits and heaps of dust to be considered as sources of explosive atmospheres. We have also addressed the risks caused by dust in our article on the Regulation on Dust Control.
At the entrances to hazardous zones, the warning sign described in Annex 4, triangular, with a black border and black lettering on a yellow background, is placed. You can find the general rules for signs in our article on health and safety signs.
Selecting Ex equipment: category, marking and temperature class
Unless otherwise stated in the document, Annex 3 of the regulation sets the category of equipment and protective systems according to the zone:
- Zone 0 or 20: category 1 equipment
- Zone 1 or 21: category 1 or 2 equipment
- Zone 2 or 22: category 1, 2 or 3 equipment
The category is written in the Ex marking on the equipment label. For example, “II 2G” indicates equipment suitable for non-mining areas (group II), category 2 and gas atmospheres (G); the letter “D” indicates a dust atmosphere. The temperature class on the label (T1 to T6) shows the highest temperature the equipment surface can reach and must remain below the ignition temperature of the substance in the atmosphere. For gases there are also gas groups IIA, IIB and IIC; IIC is the most demanding group.
On the product side, the regulation’s text refers to the regulation parallel to 94/9/EC; this product regulation has since been renewed in parallel with 2014/34/EU. When purchasing, ask the manufacturer for the declaration of conformity and the user manual.
Contents of the explosion protection document
Under Art. 10 of the regulation, the employer prepares the document, which must show in writing at least the following:
- That the explosion risks have been determined and assessed
- The measures taken to meet the obligations in the regulation
- The areas classified under Annex 1
- The areas where the minimum requirements in Annex 2 and Annex 3 apply
- That workplaces and work equipment are designed, operated, inspected and maintained in line with safety rules
- The conformity of all work equipment with the Regulation on Health and Safety Requirements for the Use of Work Equipment
The document is prepared before work begins; it is reviewed and updated when significant changes, extensions or alterations are made to the workplace, work equipment or work organisation. It can be combined with the risk assessment and other reports.
The practices that are the on-site counterpart of the document are listed in Annex 2: employees in places where explosive atmospheres may form receive explosion protection training; where the document deems it necessary, work in hazardous places is carried out according to written instructions and a permit-to-work system is applied. Before operations begin, the explosion safety of the workplace is verified by competent persons trained or experienced in explosion protection. Where employees may carry static electricity, PPE made of suitable material is provided; earthing and equipotential bonding are checked separately. For inspecting the electrical installation, see our article on earthing and residual current devices.
Common mistakes
The shortcomings we often see in inspections and site reviews are these:
- The document was written once and not updated when a new paint booth or a new solvent was added.
- The zone map does not match the layout on site; machine locations have changed.
- There is no list of Ex equipment, or the label information has not been compared with the zone and substance properties.
- Dust deposits are cleaned with compressed air, creating a dust cloud.
- Earthing connections were not refitted after maintenance.
- There are no warning signs or permit-to-work arrangements at the entrances to hazardous zones.
At Bursa Sistemer OSGB, we plan the assessment of explosion risk together with the general risk assessment under our risk assessment service. For risks specific to chemical and plastics businesses, see our chemicals and plastics sector page.
Frequently Asked Questions
For whom is the explosion protection document mandatory?
It is mandatory for all workplaces within the scope of Law No. 6331 where an explosive atmosphere may form. The criterion is not the size or hazard class of the workplace, but the likelihood that an explosive atmosphere will form due to flammable gases, vapours, mists or dusts.
What is the difference between Zone 1 and Zone 2?
In Zone 1, an explosive atmosphere is likely to occur occasionally during normal operation; in Zone 2, it is not expected in normal operation and, if it occurs, lasts only a very short time. Category 1 or 2 equipment is used in Zone 1, and category 1, 2 or 3 equipment in Zone 2.
When is the document updated?
It is reviewed when significant changes, extensions or alterations are made to the workplace, work equipment or work organisation. A new chemical, a new paint booth or a change in ventilation are typical reasons for an update.
Is a document prepared before 2013 valid?
Under provisional Article 1 of the regulation, documents prepared under the old 2003 regulation are accepted as valid. However, if there have been significant changes since then, the document should be updated.
A risk assessment that identifies and scores hazards on site, links each measure to an owner and a date, and has a clear renewal schedule.
Bursa SİSTEMER OSGB Technical Team — written from the field experience of our OHS specialists and workplace physicians. Legal information is valid as of the publication/update date; contact us for an assessment specific to your business.