Explosion-proof (Ex-protected)

An explosion occurs when three factors occur at the same time:

• Fuel: flammable gases, vapours, dusts or fibres.

• Oxygen: usually from the ambient air.

• Ignition source: electrical sparks, hot surfaces or mechanical sparks.

Explosion-proof equipment and systems prevent these factors from interacting and so ensure safety.

Explosion zones

Zone	Description
Zone 0	Area in which an explosive atmosphere is present continuously or for long periods.
Zone 1	Area in which an explosive atmosphere can occur occasionally.
Zone 2	Area in which an explosive atmosphere occurs only rarely and for a short time.

Various protection concepts exist for working safely in potentially explosive atmospheres:

Protection concept	Description	Application
Type of protection “flameproof enclosure” (Ex d)	Enclosure that withstands explosions inside it and does not allow flames to escape.	Electrical switchgear
Increased safety (Ex e)	Measures that minimise the probability of ignition, e.g. by avoiding sparks.	Lighting, terminal boxes
Type of protection “intrinsic safety” (Ex i)	Limiting the electrical energy below the ignition limit.	Measuring and control devices
Pressurised enclosure (Ex p)	The interior of an enclosure is filled with compressed air or inert gas to prevent gases from entering.	Control cabinets, controllers
Encapsulation (Ex m)	Electrical components are embedded in a solid material such as resin.	Sensors, electronic parts

Explosion protection is subject to strict international regulations and standards to ensure uniform safety standards.

Important standards and directives

• ATEX directive (EU): sets out the requirements for equipment and protective systems in potentially explosive atmospheres.

• IECEx certification: international standard for the certification of equipment for hazardous areas.

• NFPA 70 (NEC): regulations for explosion-proof electrical installations in the USA.

• Ensuring safety: protection against explosions and potential damage to people, plants and the environment.

• Compliance with legal requirements: the equipment complies with international standards and directives.

• Durability: resistance to extreme environmental conditions such as heat, moisture or aggressive chemicals.

Feature	Explosion-proof equipment	Standard equipment
Area of use	Potentially explosive areas (Zone 0, 1, 2)	Normal environments
Safety concepts	Specifically designed for explosion protection	No special protective devices
Costs	Higher, due to special materials and tests	Lower
Service life	Resistant to extreme conditions	Limited in extreme environments

• What does ATEX mean? ATEX stands for “Atmosphères Explosibles” and refers to the EU directives on explosion protection.

• Which industries need explosion-proof equipment? The electrical industry, chemicals, oil and gas, mining, food processing and any industry that works with flammable substances.

• What is the difference between Zone 1 and Zone 2? Zone 1 is an area in which an explosive atmosphere can occur occasionally, while in Zone 2 such atmospheres are less likely to occur.

• How is explosion-proof equipment tested? The equipment undergoes rigorous tests and certification according to the relevant standards, e.g. ATEX or IECEx.

Explosion-proof equipment is indispensable for work in potentially explosive atmospheres. By using modern protection concepts and complying with international standards, it makes a major contribution to the safety of people and plants. Whether in the rubber and plastics industry, the chemical industry or food processing, explosion protection ensures the highest level of safety.