IoT and gas meter:
ATEX zone
How to use IoT networks and sensors in SEVESO sites or ATEX zones in complete safety?
What is an ATEX area?
Any place where the risk of explosion is considered significant due to the presence of flammable materials is considered an ATEX Zone.
The acronym ATEX stands for: ATmosphere EXplosive
Depending on the nature and quantity of the flammable material, the risk is considered more or less high. The higher the risk, the stricter the regulations.
In order to evaluate the level of risk of an ATEX zone, many data are taken into account: nature of the combustible products, relative density, minimum explosive concentration, compatibility or not with other chemical products,…
There are two main categories of ATEX zones:
- Zones where the flammable substance is in the form of a gas, mist or vapour,
- Areas where the substance is in the form of dust.
European regulation on ATEX:
- Directive 2014/34/UE or ATEX 95: for manufacturers of products intended for an ATEX zone
- Directive 1999/92/CE or ATEX 137: on the duties of the site manager
Focus on: deployment zones
- Zone 0 (for gas and steam) and Zone 20 (for dust) = 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 (for gas and steam) and Zone 21 (for dust) = 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 (for gas and steam) and Zone 22 (for dust) = 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.
How to make installations located in explosive atmospheres 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 have different characteristics and not all of them can be used in the same places. Each ATEX product is associated with:
- a deployment zone,
- a heating level: the temperature class characterises the explosive atmosphere in which a product can operate (it consists of 6 categories),
- a flammability level: the possible flammability of the product. It is characterised by the maximum amount of energy that must be supplied to cause an explosion (3 levels).
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.
How to monitor gas meters?
It is possible to make your gas meters communicating in ATEX zones. To do this, it is essential to use sensors that meet the relevant ATEX standards.
When designing them, a number of requirements must be taken into account in order to limit any risk of exposure, which would be very serious in an explosive atmosphere.
These IoT / ATEX solutions offer the possibility to make your equipment and buildings connected, to :
- monitor and optimise actual gas consumption,
- detect possible overconsumption of energy or gas leaks,
- be informed quickly and act as soon as possible, as soon as a threshold is exceeded.
Focus on: IoT / ATEX adeunis sensors
The adeunis PULSE ATEX IoT sensor is certified for:
- Group II (surface industries),
- Category 2G (zone 1 and 2) for the most flammable gases of Group IIC (hydrogen, acetylene, carbon disulphide) and Group IIIC for conductive dusts.
This sensor exists in 3 versions. The BINDER and GAZPAR versions have integrated connectors for easy installation on the appropriate gas meters.
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[1]. 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[2], 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.
Depending on the zone in which it is to be deployed, the characteristics of the IoT sensor are not the same. In zone 0 or 1, the risks are very high and the requirements are very strict.
Indeed, the release of sufficient energy by the product (in the form of heat or sparks) could cause a very serious explosion due to the ignition of a gas or dust cloud. For this reason, products meeting the requirements of zones 0 or 1 are certified by notified laboratories, which verify that they meet all the requirements of ATEX (product design, specific quality level expected and administrative follow-up). These certifications are therefore an assurance that the risks inherent in these dangerous zones are taken into account.
[1] Capacitance and inductance: electronic components
[2] Sensor capable of counting electrical pulses
14/03/2021
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