How to interpret the marking to determine the Ex zone of use.

At this stage, how can we determine under which conditions a certified device can be used safely? The answer can be found in the correct interpretation of the marking on the product: a code that may seem indecipherable at first glance, but actually contains very valuable information.

Let's consider, for example, the marking:

II 2G Ex emb op is IIC T4 Gb

II 2D Ex tb op is IIIC T75°C Db

These abbreviations, although they seem complex, are not random at all: each of them provides precise information.

· Group (II): defines the conditions of use, usually “II” for industrial areas on the surface.

· Category (e.g. 2G, 2D): indicates the probability and duration of the presence of an explosive atmosphere (e.g. ‘2’ for occasional presence).

· Next letter (G or D): distinguishes between gas (G) and dust (D).

· Type of protection (Ex emb, Ex tb, etc.): indicates the protection technology used.

· Gas or dust group (IIC, IIIC): links the equipment to a family of compatible substances.

· Maximum temperature (T4, T75°C): indicates the maximum safe surface temperature.

How to determine the correct zone: simply compare the category and letter with the classification zones:

· 1G / 1D → Zones 0 / 20 (permanent presence of explosive atmosphere)

· 2G / 2D → Zones 1 / 21 (periodic presence)

· 3G / 3D → Zones 2 / 22 (rare or short-term presence)

Thanks to this system, the user can accurately determine the environment in which the device can be used safely by simply reading the label and correlating it with the risk category of the working area.

Example of ATEX marking: how to read the markings on devices

Equipment certified for use in potentially explosive atmospheres is marked with codes such as:

II 2G Ex emb op is IIC T4 Gb

II 2D Ex tb op is IIIC T75°C Db

These sequences, which may seem incomprehensible at first glance, actually contain important information about the characteristics of the device. Here is the basic information that ATEX marking always provides:

· Category and group of belonging: indicate whether the equipment is intended for atmospheres with gases (G) or dust (D), the expected level of protection and the type of substances present.

· Type of protection: indicates the system used, such as ‘Ex d’ (explosion-proof), ‘Ex e’ (increased safety) or ‘Ex ia’ (intrinsic safety), which have already been described in detail in the previous sections.

· Gas/dust groups: abbreviations such as IIC or IIIC indicate the groups of substances with which the device is compatible.

· Temperature class or temperature limit: indicates the maximum surface temperature of the device during normal operation (e.g. T4 or 75 °C).

· Protection level and destination zone: letters such as Gb or Db indicate the zone in which the equipment can be installed (Gb for gas zones, Db for dust zones).

· Authorised testing body: in some cases, the code of the body that carried out the certification in accordance with ATEX standards is also indicated.

How to decipher the marking

For example:

· ‘II’ means that the equipment is intended for use in conditions other than mining.

· “2G” means that it can be installed in zone 1, where gas is likely to be present with a risk of explosive atmosphere.

· ‘Ex emb op is’ describes the type and method of protection.

· ‘IIC’ denotes the group of the most dangerous gases, such as hydrogen and acetylene.

· ‘T4’ indicates a maximum surface temperature of 135 °C.

· The final abbreviation (‘Gb’ or “Db”) defines the level of protection, where ‘b’ means high safety.

Practical application