Overview of ATEX Zones and Equipment

Overview of ATEX Zones and Equipment

Ex-Machinery explains “which ATEX equipment may be used in which ATEX zone?”

put this practical overview on your bulletin board


Within Europe, when electronic or electrical equipment of any kind is intended for use in a potentially hazardous area, the equipment must be ATEX-certified – per the EU directive 2014/34, which is more commonly known as the ATEX 114 directive (derived from the French: ATmospheres EXplosives).  ATEX equipment is classified into groups and categories which are defined by the markings on the equipment. Hazardous areas are divided into zones – according to how likely a potentially explosive atmosphere may be present. For many of our clients, the dilemma is how to know which ATEX equipment may be used in which zone. As specialists in ATEX and explosion safety, Ex-Machinery provides an easy reference guide to help answer these questions. Let’s have a look…

ATEX equipment and zones de-mystified

An ATEX zone 2 air conditioner goes into category 3 explosion-proof equipment. For use in ATEX zone 1, category 2 explosion-proof equipment is required. Does this make sense? You probably don’t think so, but we promise you that there is an obvious explanation.

“Which ATEX equipment do we need in our ATEX zone?” is a common question that we hear from our customers. It can be confusing sometimes, which is why Ex-Machinery has listed the various ATEX zones, and their corresponding required equipment in one handy, easy-to-read table, along with a detailed explanation.

Zones start counting at 0 (gases) and 20 (dust). Equipment starts counting at 1. Both terms, ATEX zones and ATEX equipment, have their own origin and their own way of numbering. More on that later.

Table 1: Relationship between ATEX Zones and required equipment.

Presence of explosion hazards in the ATEX zone

The more frequent an explosive gas or dust cloud is present, the more dangerous the zone. Therefore, always try to avoid or reduce the zone. A hazardous area classification is mandatory and written down in the Explosion Protection Document. Shaded areas on the map of the industrial site (see the figures, below) indicate the size and shape of the hazardous areas.

• G stands for  gas explosion hazard
• D stands for dust explosion hazard

To reduce explosion risks, there are several available solutions. These are both technical and organizational measures. Also important to note is that the lower the ATEX zone, the less expensive the explosion-proof equipment. And the cost of such equipment is considerable – all the more reason to make limiting the occurrence of an explosive atmosphere a number 1 priority. A measure, like specific ventilation, is often an effective and relatively inexpensive solution for zone reduction. We have experienced situations where ATEX zone 0 has been reduced back to ATEX zone 2 – just with the help of ventilation. In general, we see that 80% of all ATEX zones are set as a zone 2 or 22.

In practice: ATEX zone reduction

The extent of the impact of explosion-reducing measures is shown in the example below.

Figure 1: Situation before implementation of safety measures. Mostly purple (ATEX zone 1) and red (ATEX zone 0).

Figure 2: Situation after implementing measures. Mostly green (ATEX zone 2) and purple (ATEX zone 1).

ATEX zones, equipment groups and categories

When the ATEX zone is clear, the table helps you to find the accessory equipment. ATEX equipment is classified into equipment-groups. Equipment groups are divided into categories. We are almost there.

ATEX equipment group I:

Equipment in this category is only intended for use in the underground areas of mines, as well as those areas of surface installations of such mines endangered by firedamp and/or combustible dusts.

ATEX equipment group II:

Equipment in this category is intended for use in areas in which explosive atmospheres caused by gases, vapours, mists or air/dust mixtures are likely to occur occasionally. Think of production facilities in the food industry, chemical plants, oil & gas, and the pharmaceutical industry – to mention a few.

⇒ Categories within equipment group II:

Equipment category 1
Equipment in this category is intended for use in Zone 0 areas (gases) or Zone 20 (dusts), and must ensure a very high level of protection (i.e. the inside of tank truck or the interior of a dust filter). The design of the equipment must ensure protection, even in the event of rare incidents relating to the equipment. And safety must be guaranteed in the case of two faults occurring independently of each other. Most equipment is not zone 0 approved, because these areas are small and engineering and certification are expensive. An example of equipment that comes with category 1 certification is this explosion proof work light.

Equipment category 2
This equipment is intended for use in Zone 1 (gases) or Zone 21 (dusts). A high level of protection is ensured.  You will find these zones at the manifold of a tank truck or the interior of a silo. Safety is ensured in the event of frequently occurring disturbances or equipment faults which normally have to be taken into account.

Equipment category 3
Is intended for us in Zone 2 (gases) or Zone 22 (dusts). Explosion protection must be ensured during normal operation. You will find this equipment in paint factories, a warehouse or around a bag dump station. Ways to ensure this level of safety are non-arcing design and limitation of the temperature of the equipment.

Hazcalc is a quick and easy software tool to assist with Hazardous Area Classification (HAC)

ATEX marking

G stands for the presence of gases, vapours or mists. D stands for the presence of air/dusts mixtures. ATEX marking is applied to all equipment that is proved to be suitable for use in ATEX Zones.

Figure 3: The marking of this explosion proof Wi-Fi Unit says Ex II G3, which means that this device is explosion-proof for gas explosion hazardous environments Zone 2.

So there you have it. We hope that we have helped to clarify some of the confusion surrounding this very important question: “Which ATEX equipment do we need in our ATEX zone?” And if you need any more information or explanation, we will be most happy to assist. After all, Ex-Machinery has specialized in ATEX and explosion safety for well over 14 years, so please do follow our ATEX specialist Gido van Tienhoven on LinkedIn – where no ATEX question will go unanswered. We look forward to hearing from you.