10 questions and answers about explosion protection

Only dissipative clothing can be worn in hazardous areas. FFP2 masks are made of insulating material, so it is important to consider whether dangerous charges could be present. When they are worn as intended, there is no risk of this happening.

Since the mask is in direct contact with your body when worn, it becomes damp. As a result, the surface resistance on the inside of the mask rapidly decreases. FFP2 masks can therefore be considered dissipative. This means that they can be worn in hazardous areas for materials in explosion groups IIA and IIB in Zones 1 and 2, provided that:

• The activities do not involve any processes that will generate a significant charge
• No metallic components are present on the surface of the FFP2 mask

Masks must be put on and removed outside the hazardous area.

Please also note that FFP2 masks do not protect you against gases or vapours, or in the event of a lack of oxygen.

No, a smartphone is a device according to the ATEX directive and requires approval. Devices without approval, regardless of whether they have a built-in battery, may not be taken into areas with explosive atmospheres.

The reason for this is that mobile phones generate electromagnetic fields that can, for instance, heat up small metal components. This means that there is a risk of these components becoming a source of ignition. The EN 60079-14 standard specifies the peak power up to which the electromagnetic field generated by a smartphone is considered not to be a source of ignition.

Mobile phone cases also pose a potential hazard. These are often made of plastic which can become electrostatically charged. This can cause electrostatic discharge, meaning that the mobile phone case becomes a potential source of ignition.

In the case of watches, due to their enclosure size and design, the Komitee 235 group belonging to the German Electrotechnical Commission has stated that no explosive atmosphere can penetrate a watch, even taking particularly unfavourable circumstances into account. As a result, electrically powered watches with no additional special functions (e.g. a calculator function) pose no explosion hazard in Zones 1 and 2. Wall clocks, in contrast, must be designed to be explosion-protected (for instance with II 2 G Ex e mb IIC T6 label).

When it comes to hearing aids, both the battery voltage and any ignitable inductive electrical circuits must be taken into account. In any case, the ignition hazard posed by compact devices worn in the ear is deemed to be low enough that they can be worn in Zones 1 and 2. Associated remote operation devices are excluded from this rule.

The use of pocket calculators in hazardous areas requires a case-by-case inspection and approval process, even for solar-powered devices, because ignitable voltages can be generated above a certain number of solar cells.

If an explosive atmosphere is created, the area does not necessarily need to be divided into zones. Zone classification into Zones 0, 1 and 2 for gas, mist and vapour atmospheres and Zones 20, 21 and 22 for ignitable dust atmospheres is designed for areas in which there is a certain probability of an explosive atmosphere being created that could be ignited by a source of ignition, causing an explosion.

The required protection level of the devices is determined by the probability of an explosive mixture being created. If the explosive atmosphere is only present at very specific, precisely predictable times – for example when opening a container – a protective zone does not have to be assigned. Instead, as part of a risk assessment, specific protective measures can be implemented for the time in which the hazard is present.

Yes. However, when retrofitting the terminals, you must comply with the manufacturer's operating instructions. This means that you may only use terminals that the manufacturer has included in their certificate (e.g. made by certain manufacturers, of specific size or classification). Additionally, the terminals require a U certificate, as they must be certified as Ex e components. Why? Because the terminal boxes must be tested with regard to these terminals. Furthermore, you may only retrofit a certain number of terminals. The maximum number is also specified in the operating instructions.

This is permitted – after consulting the manufacturer. The manufacturer's operating instructions specify the requirements – i.e. how many drilled holes to create on which sides and of what size, as well as the gaps between them, in order to guarantee stability. However, any retrofitting work performed is the customer's own responsibility and must be tested by them.

Hermetically sealed screw connections and hermetically sealed stopping plugs can also be fitted in Ex e enclosures. According to applicable standards, these components are approved for use in Ex e enclosures. However, the reverse does not apply.

However, plastic enclosures (Ex e) with screw connections and metal stopping plugs (Ex d) must be earthed to eliminate any voltage transfer to the enclosure.

Sparks generated mechanically by processes involving friction, impacts, grinding or drilling represent sources of ignition as per EN 1127-1. Whether and to what extent the formation of sparks caused by the use of tools is permissible depends on the corresponding protective zone and the ignitability of the explosive substances. In Zones 0 and 20, no tools that could generate any sparks may be used.

Stainless steel tools such as screwdrivers or wrenches, which typically generate only a single spark when used, but which do not generate any bursts of sparks or hot surfaces, may be used in Zones 1 and 2. However, this does not apply for Zone 1 if there is an explosion hazard in the zone caused by substances in explosion group IIC (acetylene, carbon disulphide and hydrogen) or due to hydrogen sulphide, carbon monoxide or ethylene oxide. In this case, special measures to prevent the generation of ignitable sparks must be taken.

In Zones 21 and 22, the use of stainless steel tools that do not generate any bursts of sparks or hot surfaces is generally permitted. If this cannot be guaranteed, the workplace must be cleared of all dust deposits and shielded to separate it from the surrounding zone area. Additionally, it must be kept humid while the tools are being used, in order to prevent dust from being thrown up and glowing embers from being produced.

Low-sparking tools are therefore not permitted in hazardous areas as a rule. In individual cases, however, they can be practical. However, a risk assessment of the operation is always required.

Where combustible dusts and combustible gases or vapours are present, this is referred to as a hybrid mixture. These types of hybrid mixtures can have critical key characteristics that differ from the individual substances. The IEC 60079-14 standard, appendix M, contains some information that should be taken into account. As, in practice, the situation can present itself very differently, a risk assessment must be performed in order to determine suitable measures. Devices that are approved for both gas and dust hazardous areas may therefore not be used freely in areas with a hybrid mixtures.

The protective measures for the devices (one for gases and one for dusts) do not necessarily exclude combinations. This, for instance, is how the temperature class is determined for a device approved for operation in gas atmospheres with no deposited dust layer. However, dust deposits increase the surface temperature of an enclosure or the installed devices, and therefore also the explosion hazard. In the case of flameproof enclosures that are exposed to hybrid mixtures, there is a risk of dust deposits in ignition puncture-proof joints, which may be ejected as hot particles in the event of an internal explosion, thereby posing an ignition hazard. For these reasons, a special assessment and inspection is required when using explosion-protected devices in an environment with hybrid mixtures.