EGE-Elektronik Spezial-Sensoren GmbH - Special-Sensors for Automation

ATEX Gas Ex - Fundamentals

ATEX 100a

This term indicates compliance with the 94/9/EU directive, which prescribes European-wide guidelines for handling equipment and protective systems in potentially explosive atmospheres. As of 1 July 2003, these regulations will be binding and thereby guarantee free movement of EX products in the EU. From this date on, products that were developed and manufactured in accordance with national EX standards may no longer be traded. This ends the transitional period for operators of facilities. From this date on only facilities that have been approved under ATEX may be operated. One provision, in particular, that is new is that now areas that are subject to dust exposure are included in the ATEX. Operations where dust accumulates or is processed must therefore come to terms with the new directives.

Zone classification in the gas area

Facilities in which explosion hazardous atmosphere can be generated are divided into three zones.

Zone 0 EX atmosphere present frequently or constantly or long-term

Zone 1 EX atmosphere occasionally present

Zone 2 EX atmosphere present very seldom and then only for a short period.

The operator is responsible for zoning.

Diagram of a possible zoning allocation for a gas operation

Product identification

ATEX 100a prescribes a uniform identification of the equipment approved for use in potentially explosive areas.

the equipment group:      II (all areas except mining)
the equipment category: 1G = use in zones 0, 1, 2
                                    2G = use in zones 1, 2
                                    3G = use in zone 2

Method of protection
i intrinsically safe
ia certified for Zone 0
ib certified for Zone 1
e increased safety
m molded, encapsulation

Explosion sub-groups    
All industry gases/vapours are classed as Group II gases. Group II is sub-divided into 3 sub-groups.

IIA High energy is required to ignite.  (Ethyl alcohol, fuel, propane)
IIB Less energy is required to ignite.  (Ethylene, lightning gas, ethylene)
IIC Little energy is required to ignite. (Hydrogene, acethylene)

Temperature classes
Gases and vapours are divided into temperature classes. According to these temperature classes,  explosion-protected equipment  is designed in such a way that ignition by the surface is not possible. The temperature class is dependant on the medium.

Temperature classes ATEX

Approval for safety applications
Sensors for personal security must have a qualifification approval according to EN 954-1 and must be labeled accordingly. Sensors that are not labeled must not be used for applications of this kind.

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