• The ATEX directive and Fortress products
• Trapped key systems
• Ex Zones
• Standards and the ATEX directive
• Further information

The ATEX directive and Fortress products

This guide is intended to serve as an introduction to the main topics surrounding the ATEX Directive. It should not be considered as an alternative to obtaining the official European standards.

Fortress interlocks are able to supply equipment suitable for environments where there is a risk of explosion due to a flammable atmosphere being present.

In the European Union, the requirements for equipment and protective systems intended for use in potentially explosive atmospheres are covered by compliance with the essential health & safety requirements (EHSR’s) of the ATEX (94/9/EC) directive. (ATEX is derived from the French "ATmosphere Explosible)."

Essential Health and Safety Requirements are specific with respect to:

• Potential ignition sources of equipment intended for use in potentially explosive atmospheres;
• Autonomous protective systems intended to come into operation following an explosion with the prime objective to halt the explosion immediately and/or limit the effects of explosion flames and pressures.
• Safety devices intended to contribute to the safe functioning of such equipment with respect to ignition source and to the safe functioning of autonomous protective systems;
• Components with no autonomous function essential to the safe functioning of such equipment or autonomous protective system(s).

Since 1 July 2003 relevant products could only be placed on the market in the EU territory, freely moved and operated as designed and intended in the expected environment if they comply with Directive 94/9/EC (and other relevant legislation).

The ATEX Directive is based on Article 95 of the EC Treaty and provides for harmonised requirements and procedures to establish compliance (generally in the form of European harmonised standards). The intent is to provide free movement of goods within the European Union, based upon common regulatory requirements.

Trapped key systems

Fortress stainless steel trapped key systems are a highly reliable and robust method of interlocking. Because they have no electrical parts they do not generate heat or sparks. They are therefore an ideal choice for use in hazardous areas. The materials used in these trapped key systems are made of stable, non-sparking metals. These materials prevent the creation of sparks when moving parts (such as door lock actuators) strike each other in use.

Electrical control and interlocking devices

Electrical devices such as the Fortress heavy-duty explosion protection safety gate switch STOPTX incorporates an approved flameproof switching system. In addition, external parts that are liable to encounter mechanical impacts are made from the same robust and non-sparking materials found in the trapped key range.

Ex Zones

Zones are areas where equipment is installed that has a risk of a explosive atmosphere being present. They are divided into 3 main zones:

Zone 0:- A location where an explosive atmosphere consisting of a mixture of with air or flammable substances in the form of a gas, vapour or mist is present continuously or for long periods. (Dust = zone 20).

Zone 1:- A location where an explosive atmosphere consisting of a mixture of with air or flammable substances in the form of a gas, vapour or mist is likely to occur in normal operation occasionally. (Dust = zone 21).

Zone 2:- A location where an explosive atmosphere consisting of a mixture of with air or flammable substances in the form of a gas, vapour or mist is not likely to occur in normal operation occasionally but if it does will occur will only persist for a short period only. (Dust = zone 22).

Once the zones have been determined and the gasses or dusts that will be present are known, the process of selecting the correct equipment can be started.

Fig 1. Ex Equipment markings

Category / Code	Interpretation/Information
	Symbol denotes mining equipment explosive protection
	Symbol denotes CENLEC marking for explosive protection
Industry Group II 1 G EEx d IIC T6	I = Mining (below ground) II = General (above ground)
Zone of Application II 1 G EEx d IIC T6	Category 1 equipment suitable for Zone 0 or 20. Category 2 equipment suitable for Zone 1 or 21. Category 3 equipment suitable for Zone 2 or 22.
Type of Hazard II 1 G EEx d IIC T6	G = Gas D = Dust
ATEX Certification II 1 G EEx d IIC T6	E = Certified to CENELEC Std Ex = Explosion Protected
Method of Protection II 1 G EEx d IIC T6	Protection concept (see Fig 2.)
Gas Group II 1 G EEx d IIC T6	IIA = Gas Group IIB = Gas Group IIC = Gas Group
Temperature Class (Maximum Surface temperature) II 1 G EEX d IIC T6	T1 = Temp Code 450 C T2 = Temp Code 300 C T3 = Temp Code 200 C T4 = Temp Code 135 C T5 = Temp Code 100 C T6 = Temp Code 85 C

Standards and the ATEX directive

The use of European harmonised standards offer a “presumption of compliance” with the their applicable directive. A wide variety of protection concepts are covered. The following chart explains the way the correct protection concept is matched to the zone.

Fig 2. Protection Concepts

Further information:

Please refer to the E.U. official website for the full text of the ATEX directive and details of the harmonised standards: http://ec.europa.eu/enterprise/atex/