Brochure/Catalogue

Grundlagen zum Explosionsschutz
The surrounding explosive atmosphere can penetrate into
the enclosure and it can cause an internal explosion during
the lifespan of the device.
The enclosures must be stable enough that they are not
deformed or destroyed by the pressure created. All of the
enclosure’s couplings and connections are designed so
that they will not transmit an internal explosion to the
surrounding outer atmosphere. These couplings are referred
to as ignition gaps.
The explosion group (IIA, IIB, IIC) is relevant for this ignition
protection type. Devices using this protective strategy may
not be used in Zone 0.
Classication of devices into groups
Gas Ex protection is divided into Groups I and II. In Group
II, ammable gases, vapours and mist are subdivided into
subgroups IIA, IIB and IIC, depending on their capability to
ignite or their explosive transmission capacity.
Electrical devices in the Group II category should be used for
dust Ex protection. These are subdivided according to the
properties of the dust where they can be used. Sub-group
IIIA is for combustible yings, IIIB is for non-conductive dust
and IIIC for conductive dust.
EN 60079-0 ATEX Directive EN 60079-10-X
Flammable
materials
EPL Group Equipment
group
Equipment
category
Type of
explosive
atmosphere
Zone
Methane,
Coal dust
Ma
I I
M 1
NA
Mb M 2
Gases, mist,
vapours (G)
Ga
II
II
1 G 0
Gb 2 G 1
Gc 3 G 2
Dust (D)
Da
III
1 D 20
Db 2 D 21
Dc 3 D 22
In an explosive atmosphere, the maximum surface
temperature of Ex devices is a critical factor. It must
therefore be specied on the ratings plate of an assembled
(non-empty) Ex enclosure (refer to the ratings plate for an
assembled Ex-certied enclosure on p. 36). For dust-related
Ex protection, the maximum surface temperature is specied
directly (e.g. T 100 °C). For gas-related Ex protection, there
is a division into temperature classes ranging from T1 to T6
(refer to the table on the right).
For example, an enclosure with a T6 rating has a maximum
surface temperature of 85 °C. Thus it can also be used in
T5–T1 zones since the temperatures in these zones do not
exceed 85°C.
Classication of gases and vapours into explosion groups and temperature classes
Temperature class T1 T2 T3 T4 T5 T6
Max.
surface
temperature
450 °C 300 °C 200 °C 135 °C 100 °C 85 °C
Explosion group
I Methane
II A
Acethone
Ethan
Ammonia
Benzene
Acetic acid
Carbon
monoxide
Methane
Methane_1
Propane
Tolu_1
Ethyl
alcohol
i-amyl
acetate
n-butane
n-butyl
alcohol
Gasoline
Diesel
power --
Acetalde-
hyde
II B
City gas
(Coal gas)
II C Hydrogen
Carbon
disulphide
Required labelling
A device can only be commissioned after it complies with
the relevant ATEX directive. Two key prerequisites are a
unique CE mark and an attached declaration of conformity
for the device. An afxed CE mark conrms that the product
complies with all applicable requirements found in the
directives which are relevant to that product. The declaration
of conformity conrms compliance with the relevant
directives.
352454030000