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ATEX Groups & Zones

ATEX Groups & Zones


Groups -

Equipment for mines
Group I

Firedamp content

Any firedamp content

Beyond limiting value

Category of equipment which may be used following 2014/34/EU directive

M1

M2

Equipment for surface installations
Group II

Zones

0

20

1

21

2

22

Nature of atmosphere

G
gas

D
dust

G
gas

D
dust

G
gas

D
dust

Explosive atmosphere

Continuously present

Not likely to be present

Accidentally present

Category of equipment which may be used following 2014/34/EU directive

1

2

3

Zones -
Hazardous areas for Group II are further divided in zones, these zones relate to the predicted occurrence of when an explosive atmosphere may be present in the area. These zones are defined as being:

Color

Zones

Presence of gas/dusts

 

0

Continuously present (during long periods)

 

1

Not likely to be present (regular service)

 

2

Accidentally present (short-time-service - never in regular service)

 

Color

Zones

Presence of gas/dusts

 

 20 

Continuously present (during long periods)

 

21

Not likely to be present (regular service)

 

22

Accidentally present (short-time-service - never in regular service)

 

Types of Protection -

Protection symbol

Zones

Description

Symbolic drawing

0

20

1

21

2

22

"c"

 

 

 

 

 

 

Protection by constructional safety according to EN 13463-5
This standard establishes manufacturing requirements which have been proven safe, in order to avoid any inflammation sources such as friction or heating sparks. It applies to apparatus where movement and friction can occur (clutches, brakes, bearings, springs...).

 

"d"

 

 

 

 

 

 

Flameproof enclosure
Refers to an electrical apparatus whose explosive parts are enclosed in an explosion proof casing. This casing will resist the pressure generated by the internal explosion of an explosive mixture and will prevent the explosion from penetrating to the ambient explosive atmosphere.

 

"e"

 

 

 

 

 

 

Increased safety
Refers to an electrical apparatus with a high safety coefficient. Such an apparatus is free from excessively high temperatures and, like under normal service conditions, cannot develop inside and outside electric arcs and sparks.

 

"i"

"ia"

 

 

 

 

 

 

Intrinsically safety
Refers to a circuit in which neither sparks nor temperature can ignite an explosive atmosphere, if generated under the service conditions specified by the standard regulations (normal and faulty operating conditions).

 

"ib"

 

 

 

 

 

 

"m"

 

 

 

 

 

 

Encapsulation
Refers to a special casing in which the parts, of an electrical apparatus which could ignite an explosive atmosphere by either sparking or heating, are encapsulated in a compound in such a way that this explosive atmosphere cannot be ignited.

 

"n"

 

 

 

 

 

 

Method of protection for electrical equipment designed so that it will not ignite the surrounding explosive atmosphere in normal operation and under certain fault conditions specified in the standard. There are 5 categories of equipment: nA (non-sparking), nC (hermetically sealed), nR (restricted breathing), nL (limited energy), and nP (simplified pressuration).

 

"o"

 

 

 

 

 

 

Immersion
Refers to electrical apparatus immersed in oil.

 

"p"

 

 

 

 

 

 

Pressurised enclosure
Pressurization is maintained against atmosphere by means of a neutral inert gas.

 

"q"

 

 

 

 

 

 

Refers to a casing containing powder filling.

 

Temperature Classes -

Group I

Temperatures < 150°C or < 450°C according to coal dust accumulation on equipment

Group II

Temperature class for gas (G)

Permissible surface temperature of electrical equipment

T1
T2
T3
T4
T5
T6

450°C
300°C
200°C
135°C
100°C
85°C

Ignition Temperature for Dusts -
The dust ignition temperature depends on its consistency and its nature. The ignition temperatures for various types of dust are available from reference tables: examples.

Dusts

Ignition temperature

Clouds

5 mm layer

Aluminium

560°C

> 450°C

Charcoal

520°C

320°C

Coal dust (lignite)

380°C

225°C

Cocoa

590°C

250°C

Coffee grounds

580°C

290°C

Corn

530°C

460°C

Methyl cellulose

420°C

320°C

Paper fiber

570°C

335°C

Phenolic resin

530°C

>450°C

Polyethylene

440°C

melts

PVC

700°C

>450°C

Sugar

490°C

460°C

Soot

810°C

570°C

Starch

460°C

435°C

Toner

520°C

melts

Wheat

510°C

300°C

Note: Temperature information for reference only.
 
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