ATEX zones

How do we identify an ATEX area?

An ATEX area is defined by the probability that an explosion could occur.
 

Explosive atmospheres can arise because of combustible gasses, vapor, mist or dust. When there is sufficient of this, mixed with atmosphere (oxygen) and an ignition source can cause an explosion. The explosive danger can express in the following forms:

• Gas explosion
• Mist explosion
• Dust explosion

The ATEX zones for gas or mist explosive risk are indicated with ATEX zone 0, 1 or 2.
The ATEX zones for dust explosive risk are indicated with zone ATEX 20, 21, 22.

In order to define the ATEX zones the following aspects need to be considered:

• Hazardous sources, all points where gas, damp or dust could possible break out need to be documented
• The quantities of gas, vapor and dust that can be released in the are calculated
• The probability is calculated that a dangerous explosive mixture is present.

We start off with the gas and/or mist explosive risks zones which are indicated with ATEX Zones 0, 1 & 2.

ATEX Zone 0 (zero)

A place in which an explosive atmosphere consisting of a mixture with air of flammable substances in the form of gas, vapour or mist is present continuously or for long periods or frequently.

An indication during normal circumstances there is high risk of explosion:

• More than 1.000 hours per year.
• >10% of the operation hours

ATEX Zone 1

A place in which an explosive atmosphere consisting of a mixture with air or flammable substances in the form of gas, vapour or mist is likely to occur in normal operation occasionally.

An indication during normal circumstances there is medium risk of explosion:

• Between 10 and 1.000 hours per year.
• Between 0,1% and 10% of the operation hours

ATEX Zone 2

A place in which an explosive atmosphere consisting of a mixture with air of flammable substances in the form of gas, vapour or mist is not likely to occur in normal operation but, if it does occur, will persist for a short period only.

An indication during normal circumstances of there is low risk of explosion:

• Less than 10 hours per year.
• <0,1% the operation hours

We continue with the dust explosive risks zones which are indicated with ATEX Zones 20, 21 & 22.

ATEX Zone 20

A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is present continuously, or for long periods or frequently.

An indication during normal circumstances there is high risk of explosion:

• More than 1.000 hours per year.
• >10% of the operation hours

ATEX Zone 21

A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is likely to occur in normal operation occasionally.

An indication during normal circumstances there is medium risk of explosion:

• Between 10 and 1.000 hours per year.
• Between 0,1% and 10% of the operation hours

ATEX Zone 22

A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is not likely to occur in normal operation but, if it does occur, will persist for a short period only.

An indication during normal circumstances of there is low risk of explosion:

• Less than 10 hours per year.
• <0,1% the operation hours