3 questions to…
Fabien de Barros, ATEX expert
How can IoT networks and sensors in SEVESO sites or ATEX zones be used in total safety? Our expert, answers your questions.
How can facilities located in an explosive atmosphere communicate via IoT networks?
In ATEX zones, the risks of explosion are greater than in other places, with these risks being due to the presence of hazardous materials (gas or dust type). It is nevertheless completely possible to use IoT protocols, provided that ATEX-certified sensors are installed.
ATEX products meet different technical needs and all cannot be used in the same places. Each ATEX product is specially associated for use in a specific zone, a level of heating and a level of flammability.
This information therefore makes it possible to know which type of ATEX sensor corresponds to which type of usage, such as, for example: monitoring the consumption of a gas meter, monitoring changes in the level of a fuel tank, accounting for the openings/closures or the filling volume of a grain silo… and therefore in what context the sensor will be used.
ATEX products are therefore known first and foremost by their deployment zone.
It also meet heating levels: the temperature class characterises the explosive atmosphere in which a product may be used (it consists of 6 categories)
Third characteristic: the possible flammability of the product. It is characterised by the maximum amount of energy needed to cause an explosion (3 levels).
Focus on: deployment zone
Zone 0 (or 20) = Devices designed for use in this zone provide a very high level of protection and are intended for an environment where an explosive atmosphere is constantly present, or for a long time. Example: inside a gas tank.
Zone 1 (or 21) = Products are designed to provide a high level of protection in an environment where explosive atmospheres will occur frequently. Example: in the vicinity of a gas tank, inside a grain silo
Zone 2 (or 22) = the devices provide a normal level of protection with a low probability of an explosive atmosphere and for a short time.
In the latter category, the products are neither controlled nor certified by a notified agency, unlike the previous two where the requirement levels are much higher, as are the risks. A notified agency is a controlled body alone authorised to issue recognised certifications: there are only 2 such laboratories in France that are able to issue this type of certification.
From a design point of view, what are the specificities of an ATEX labelled product?
When designing an ATEX product, the first step is to regulate the amount of energy in the product. The energy may come from various elements that will have to be protected.
It may come from the stack, capacitors and inductances. These are elements that can store energy in chemical form, in the form of voltage or in the form of current, respectively.
Other important elements to take into account when developing an ATEX product: product inputs/outputs. If the sensor being considered, such as a pulse sensor, is connected to another installation such as a gas meter, containing a potential source of energy, the input/output areas of the sensor must also be protected.
Thus, from the design stage, the intrinsic parameters of the sensor must take into account the type of installations that could be connected.
What are the risks incurred when using a non-ATEX product in a hazardous area?
The risks are therefore the product releasing a sufficient amount of energy (in the form of heat or a spark) that could cause a very serious explosion due to the ignition of gas or a cloud of dust.
Products suitable for zones 0 or 1 are products certified by notified laboratories, which verify that they meet all ATEX requirements (product design, expected specific quality level and administrative follow-up). These certifications are therefore the assurance of taking into account the risks inherent to these dangerous zones.