EX AREAS (IN)VISIBLY PRESENT?

Air and virtually most gases are invisible to the human eye. Although it is present. This also applies for areas with an explosive atmosphere (EX areas); high-risk areas that are invisible without clear signs, markings and instructions.

What is an EX area?

An EX area is an area where explosive atmospheres can be created by flammable gases, vapor, mist or dust. When mixed in the right proportion with the ambient air and an ignition source, this can lead to an explosion.

“explosive atmosphere’ means a mixture with air, under atmospheric conditions, of flammable substances in the form of gases, vapors, mists or dusts in which, after ignition has occurred, combustion spreads to the entire unburned mixture” (Directive 2014/34/EU)

European Directive 1999/92/EC says the following about EX Areas;

Explosion protection is of particular importance to safety; whereas 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 need to breathe.

These are high-risk areas, especially for people who are not experts in the field of EX areas. All the more important to ensure clear instructions and training. The use of explosion-proof equipment (according to ATEX157, directive 2014/34/EU) and personal protective equipment such as atmospheric detection, are therefore used as a means of prevention.

However, with all training and precautionary measures, these areas still remain 'invisible' to the eye. Signage and barriers can play an essential role here.

EX area signage and legal framework

Entering an EX area is only permitted with due observance of various safety measures. Most countries have laws and regulations in force for this, for example the European Directive 1999/92/EC (ATEX 153, formerly also known as ATEX 137).

This directive describes the following in Article 7.3 regarding signs:

Where necessary, places where explosive atmospheres may occur in such quantities as to endanger the health and safety of workers shall be marked with signs at their points of entry in accordance with Annex III.

"Where necessary" is a broad term, and open to interpretation...

Making EX areas’ boundaries visible

Visualization is indispensable when influencing behavior, primary colors and shapes are observed quickly by the human eye. Safety symbols and markings are based on these primary colors and shapes. An excellent starting point when visualizing EX areas.

According to legislation, the hazard symbol with the letters EX must be present. Noteworthy is that the symbol does not appear in ISO 7010 and, by using the two letters instead of a graphical symbol, does not comply with the design principles of safety symbols (ISO 3864). In spite of that, it is a well-known symbol. The use of yellow, possibly combined with black slanted stripes, is also associated with (explosive) hazardous areas.

This provides a basis for indicating the boundaries of EX Areas. The explosion protection document describes where the areas are located and forms the basis for the marking. For operational reasons, it is possible to choose to align the borders of an EX area with the borders of a factory or plot on site.

Possibilities for marking the boundaries of EX areas are;

• Placing signs with EX hazard symbol
• Application of floor marking (yellow lines, possibly with text on them: “EX area”)
• Deposition (e.g. yellow posts with yellow-black chain)

Safety signage is functional and effective when implemented as a system. Combining information at strategic places and working from a 'peeling principle' contributes to this. The use of composite signs makes it possible to indicate other risks in addition to the EX symbol, such as the presence of H2S, industrial traffic or loud noises. And the associated prohibitions and personal protective equipment. In this way, the boundary of the EX area can take on a broader meaning.   

EX areas in sight

In order to increase people's perception of present EX areas, there are other visual solutions, which can be combined with the border markings. These solutions are based on the identification of the environment and the contours of the hazardous areas.

The EX areas of specific equipment can be clarified with photo impression signs. In industrial environments with a variety of pipelines, equipment and structures, these photo signs provide a clear presentation of the areas. Photo signs display the equipment concerned, with a (transparently colored) contour marking of the EX Area(s).

On sites and installations where more than one area is present, overview boards can also be used. In top view or illustrative 3D impressions, with a rotation based on the location of the spectator, these signs ensure optimal information transfer of the locations and presence of EX areas. This method also gives many possibilities to visualize the different types of areas.

 The invisible visible

Even though EX areas are 'invisible' to the eye, making EX areas visible is unavoidable for a serious alignment with safety policy. A range of pragmatic and visual solutions, such as signage, barriers and in particular well thought-out and innovative signage such as the impression boards, can improve the insight into the hazardous areas for all those involved.