Technical information -
Ex-proof Signalling Equipment

Explosion-proof devices provide protection in atmospheres with flammable gases, vapours, mists or dusts.

The company's product portfolio includes visual, visual-audible and audible signalling equipment that is explosion- proof, and explosion-proof telephones have been sold with success on the global market for over 25 years now.

About explosion protection

Flammable gases, vapours, mists and dusts are formed within the chemical and petrochemical industry, i.e. from the extraction to the processing of crude oil and natural gas, as well as in many other industrial sectors that work with the production, processing, transportation or storage of flammable gases, liquids and dusts. These substances mix with oxygen in the atmosphere, creating a potentially explosive atmosphere. In the event of ignition, explosions could be caused, which might result in serious injury to people and damage to property.

As a general rule, three elements are required for an explosion to be caused - these are depicted in the internationally recognised explosion triangle symbol:

explosion triangle

Explosion-PROOF SIGNALLING Equipment

If an industry is working with a potentially explosive atmosphere, all potential sources of ignition need to be identified and switched off. As a standard signal beacon could trigger an explosion in a potentially explosive atmosphere should a fault occur, only special explosion-proof signalling equipment (Ex devices) should be used in this type of atmosphere. The obvious assumption that an explosion-proof signalling device would be protected from the consequences of an explosion is incorrect. In actual fact, the explosion-proof signalling device should not act as a source of ignition in the event of a fault and therefore not cause an explosion outside of the explosion-proof device.

Regulations for explosion-proof signalling equipment

Relevant protective regulations are in place to prevent the risk of explosions. These come in the form of laws, directives and standards, all of which guarantee high safety standards. With Directive 94/9/EC, the EU laid down the ATEX Directive (currently 2014/34/EU), which is derived from the French 'atmosphère explosible' and now brings together all of the different regulations that existed previously.

Certification of explosion-proof signalling equipment

Explosion-proof signalling equipment that complies with the ATEX Directive has to be tested and certified by independent authorities and testing institutes (e.g. PTB Braunschweig, DMT Essen, etc.) before it is manufactured and sold.

Designation and Classification of explOsion-proof signalling equipment

Below you will find an overview of the designations for the classification of typical explosion-proof signalling equipment from Auer Signal along with an explanation of the meaningsbehind them:


Auer Signal developed its first explosion-proof signalling equipment more than a quarter of a century ago.