ATEX: how to choose the lighting fixtures for places with explosive atmospheres

As set out by principle 10 of the European Pillar of Social Rights, workers have the right to a high level of protection of their health and safety at work". Evaluation of risks has to be accomplished by the employer. In case of places with presence of explosive atmospheres (ATEX), the employer will need to classify them.

The classification of ATEX zones will have to be accomplished by professionals with specific skills. They will be able to understand and evaluate the importance and the properties of flameable substances as well as the principles ruling the dispersion of gases/vapours and dusts.

In order to properly choose the lighting fixtures, it is needed to get information about the zone and the substance affecting the area.

Protection methods in use for lighting fixtures where gases/vapours are present are:

• Ex d
• Ex e
• Ex i
• Ex m

They are the only protection methods allowed given the structure and the functionality of a light source.

According to the ATEX zone, an Equipment Protection Level (EPL) equal to "c", "b", or "a" is required which corresponds to an increasing Protection Level according to the increasing dangerousness of the area.

By looking at the additional letter for the protection methods "Ex d", "Ex e", "Ex i", and "Ex m" it is possible to identify the EPL required.

LED lighting in ATEX environments

With regard to LEDs in Zone 0, they are normally used in portable torches and helmet torches with "Ex ia" protection method which corresponds to high power limitation due to the particularly high protection required.

For LEDs in Zone 1, high protection is required and the following protection methods can be adopted:

• Ex ib
• Ex db
• Ex mb

The "Ex m" method consists in encapsulated LEDs by means of transparent resins that isolate the LEDs forming the explosive atmoshere; this is mandatory because they could sparkle in a fault condition. While this system allows the use of lighter enclosures, it requires careful design and choice of electrical components to ensure high lighting and thermal performances.

For LEDs in Zone 2, the following protection methods can be implemented:

• Ex dc
• Ex ic
• Ex mc
• Ex ec

Therefore, it is the electrical material itself that ensures the necessary safety by not triggering an explosive atmosphere through electric arcs, sparks or surface overheating.

Therefore, no additional solutions are required. This results in the use of lighter and cheaper than "Ex d" housings.

Practical example:

Forklifts battery charging rooms are most likely identified as ZONE 1 and the dangerous substance is hydrogen.

Hydrogen belongs to group IIC and the temperature class is T1 because of its 500°C ignition temperature. For class T1 equipment, the maximum surface temperature is 450°C.

The type and rated parameters of the light fixtures to be used must be chosen in accordance with the required temperature class.

If light fixtures with plug-and-play LED bulbs are chosen, they must only allow the use of unmodified standard lamps without additional accessories.

Once ascertained the suitability of the environment in which an explosive atmosphere is formed during normal working activity (i.e. ZONE 1), it is also necessary to assess other main factors such as:

• Luminous flux (lm)
• Type of optics
• Luminous efficiency (lm/lm)
• Luminous efficacy (lm/W)
• Colour temperature (CCT)
• Colour rendering index (CRI)
• Lifetime of the light source
• Problems related to the disposal of worn lighting fixtures

For each lighting fixture, a datasheet containing all the necessary technical information can be downloaded from the Palazzoli's website.

Palazzoli's products for ATEX environments light up: power stations, chemical industries, oil platforms, military bases, and refineries. These are just some of the areas where lighting fixtures must prevent any risks and ensure safe and reliable operation over time.

Here are some of Palazzoli's ATEX lighting products: floodlights, ceiling lights and pendants for zones 1,2,21,22, with fluxes from 3400lm to 331000lm and efficacy up to 148 lm/W.

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