What is the difference between Zone 1 and Zone 2?

Zone 1 is an area in which an explosive gas atmosphere is likely to occur in normal operation occasionally. Zone 2 is an area in which an explosive gas atmosphere is not likely to occur in normal operation and, if it does, will only persist for a short period.

What does the ATEX marking II 2G Ex db IIC T6 Gb mean?

II = Equipment Group (surface industry), 2 = Equipment Category, G = suitable for gas atmosphere, Ex = explosion protected marking, db = flameproof enclosure protection, IIC = gas group (most volatile gases), T6 = max surface temperature class 85°C, Gb = Equipment Protection Level (high protection for Zone 1).

What standards apply to ex-proof cranes?

Ex-proof cranes must comply with EU Directive 94/9/EC (ATEX), IECEx certification, IEC 60079 standards, FEM regulations and relevant European safety standards (EN). In Turkey, regulation 94/4/AT issued on 30.12.2006 via No. 26392 is in effect.

ATEX / IECEx Overview | Zone Classification & Equipment Marking Guide

Q: What is an explosive atmosphere?

An explosive atmosphere is a mixture of dangerous substances with air, under atmospheric conditions, in the form of gases, vapours, mist or dust in which, after ignition has occurred, combustion spreads to the entire unburned mixture.

General Technical Information

An explosive atmosphere is defined as a mixture of dangerous substances with air, under atmospheric conditions, in the form of gases, vapours, mist or dust — in which, after ignition has occurred, combustion spreads to the entire unburned mixture.

The three requirements for an explosion:

Flammable gas, vapor or dust within certain limits of concentration
Air containing a minimum concentration of oxygen
An ignition source of minimum temperature and energy

Flammable gasses require only small amounts of energy to react with atmospheric oxygen, such as a spark or hot surface. Therefore, the surface temperature of mechanical and electrical equipment used is also of importance.

Flammable liquids change into vapour phase that forms a potentially explosive atmosphere near their surface. Depending on the properties of each liquid, the proportion that has evaporated into the surrounding air is determined by the temperature of the liquid.

Flammable solids in the form of dust, fibre or flyings can react with atmospheric oxygen and produce significant explosions. Dust layers begin smouldering on hot surfaces, while a dust cloud can explode immediately through contact with a hot surface or by an ignition source.

Turkey Regulation

In Turkey, "The Regulation on Equipment and Protective Systems to be Used in Potentially Explosive Environments (94/4/AT)" issued on 30.12.2006 via No. 26392 (4. rev) is in effect. This regulation is in parallel to the European Union Directive 94/9/EC.

EU Directive (ATEX 95)

Directive 94/9/EC — also known as "ATEX 95" or the "ATEX Equipment Directive" — concerns the approximation of the laws of Member States on equipment and protective systems intended for use in potentially explosive atmospheres.

The two widely used ways of reducing the risk of explosion are preventing release of dangerous substances to avoid creation of explosive atmospheres, and in potentially explosive atmospheres, preventing sources of ignition by using Ex-Proof Equipment.

Zone		Probability of a Potential Explosive Atmosphere Occurring
Gas	Dust
0	20	Always, temporarily or often present.
1	21	Occasionally present.
2	22	Very seldom or only for a short period.

Equipment Group	Equipment Category	Explosion Group	EPL	Zones
I	M1	I	Ma	NA
I	M2	I	Mb	NA
III	1G	II A	Ga	0
	2G	II B	Gb	1
	3G	II C	Gc	2
	1D		Da	20
	2D		Db	21
	3D		Dc	22

This is a technical diagram explaining Explosion-Proof (Ex) Equipment Marking, based on ATEX / IECEx standards.

Gas

Dust

ATEX / IECEx Overview

The three requirements for an explosion:

Temperature Classifications

Zone Classification

Explosion-Proof Equipment Marking

Not sure which zone or marking applies to your site?