Basis for the selection of the equipment

Zoning
Classification of potentially explosion hazardous areas
Duration– Continuous hazard Occasional hazard Temporary hazard
for information only:
Zone 0 Zone 20 Zone 20 Zone 1 Zone 21 Zone 21 Zone 2 Zone 22 Zone 22
IEC (gas) (dust) (lint) (gas) (dust) (lint) (gas) (dust) (lint)
CENELEC
Europe

Ga Da Da Gb Db Db Gc Dc Dc
Equipment protection level (EPL)

Class I Class II Class III Class I Class II Class III Class I Class II Class III

North America

Division 1 (gas and dust) Division 2 (gas and dust)

Equipment categories Equipment categories Dust groups

Gas-Ex area (ATEX) Dust-Ex area (ATEX) Dust-Ex area
Gas Dust Dust groups

INFO
Zone Symbol Category Protection Zone Symbol Category Protection Categorie Materials
requirements requirements
0 1 G required 2 independant means of 20 
1 D required 2 independant means of IIIA flammable lints

protection protection

1  2 G required,
1 G possible
1 independant mean of
protection
21  2 D required,
1 D possible
1 independant mean of
protection
IIIB non conductive dust
Explosion protection
2  3 G required,
1 G, 2 G possible
normal operation 22  3 D required,
1 D, 2 D possible
normal operation IIIC conductive dust conform to 2014/34/EU

IEC resp. EN 60079-… ATEX Directive Proof of intrinsic safety

Technical marking Legal marking
Marking of an intrinsically safe apparatus (for example): Within the EU, the equipment must comply with the appropriate provisions. According to EN 60079-14 a proof of intrinsic safety must be provided to confirm that the equip-
If a manufacturer meets these requirements, then the device is marked with the CE
Ex ia IIC T6 Ga
ment which is interconnected within an assembly accords to the requirements of intrinsic safety.
label. In this context there is a clear distinction between two basically different circuits:
0102

1. a simple intrinsically safe circuit with a single associated apparatus and at

conform to Euro- type of protection explosion group temperatur class equipment For the explosion protection according to the ATEX Directive this label will be expand- least one intrinsically safe apparatus without additional supply
pean standard (two independent protection level ed. To the CE label the number of the notified body is added, which has carried out the 2. more than one associated apparatus which is capable of supplying electrical
means of protec- QS-certification. This means, for example, that the review body of the TÜV/Hannover energy to the intrinsically safe circuit, not only during normal service but also in a fault condition.
tion) has the identification number 0044, the PTB in Braunschweig the 0102 and the DEKRA
EXAM (BVS) in Bochum the 0158.
Simple circuit

Marking of an associated apparatus (for example): Marking of an intrinsically safe apparatus acc. to ATEX (for example): The first definition of a simple intrinsically safe circuit requires to observe all electrical limit values
stated in the EC type examination certificate and the power characteristics. If these conditions are

[ IIC
met, the user is entitled to keep a proof of intrinsic safety. Inductances and capacitances of the in-
Ex ia Ga ] É II 1 G stalled cables must be taken into account.

associated conform to type of equipment associated Explosion group symbol all areas except mining very high safety level suited explosion protected against Intrinsic safety of a simple circuit is given, if the following conditions are met (application of the
apparatus European protection protection apparatus (mining = I) for zone 0 (two independent gas, vapour and mist 50 % rule for accumulated reactances):
standard level (EPL) means of protection) (D = dusts)
Additionally, the year of production and the constructional level of safety must be contained in the Associated ap- Condition intrinsically safe equip-
device’s marking. paratus ment + cable
ATEX directive
EC type examination certificate U0 ≤ UI
Marking of the EC type examination certificate acc. to ATEX: Marking of an associated apparatus acc. to ATEX (for example): I0 ≤ II
PTB 13 ATEX 2013 X É II ( 1 ) G P0 ≤ PI
authorised body year of issue acc. to serial certificate special conditions
2014/34/EU number symbol all areas except associated very high safety associated explosion pro-
mining appartus level suited for appartus tected against L0 ≥ LI + LC
(mining = I) zone 0 (two gas, vapour and
independent mist C0 ≥ CI + CC
Complete marking (for example) means of pro- (D = dusts)
Legal and technical marking tection)
The cable characteristics provided by the manufacturer should be used. Should these not be avail-
able, it is recommended to apply the following typical values (acc. to EN 60079-14):
In summary, an intrinsically safe equipment for use in Zone 0 has the following complete
marking: Preconditions for an explosion LC = 1 µH/m (30 µH/W)

II 1 G Ex ia T6*) Ga
CC = 200 pF/m
Ignition triangle Connection of proximity switches to isolating switching amplifiers, or 2-wire transmitters to isolat-
* ) On equipment for use in dust explosion hazardous areas here the maximum ing transducers, or solenoid valves to a valve control module can be considered as simple circuits.
surface temperature e.g. T140° is specified.
General guidelines for the use of devices with intrinsically safe circuits

In summary, an intrinsically safe equipment for use in Zone 0 has the following complete Sources of ignition: It is required to observe a safety distance of 3 mm (EN 60079-11) to earthed components, such
• hot surfaces
marking: as covers or side panels of mounting cabinets. A thread measure of 50 mm must be observed be-
• flames and hot gases Oxidizers:
• mechanical sparking • air (21 % oxygen) tween intrinsically safe connections and non-safe connections.

II (1) G [Ex ia Ga] IIC • electrical installations

• transient currents
• static electricity
• pure oxygen
• oxygen releasing compounds
(e.g. potassium manganate)
• lightning,
or also for the dust explosion hazardous area: ultrasonic energy

II (1) D [Ex ia Da] IIIC     

    
  
  
  
  

  

Fuels (flammable substances):  

flammable concentrations of NO
1 off
NC
WB

gases and dusts from liquids

off SC

Marking of a associated apparatus for application in zone 2:

NO NC
2 off WB
or solids which have the potential off SC

II 3 G Ex nA nC [ic Gc] IIC/IIB T4 Gc

to ignite an explosive atmosphere IM82-2414 IM1-22Ex-R IM33-22Ex-Hi
94-265VAC 24VDC
          
          

Overview of ignition protection classes


 
Symbol Name Standard Comments Zone

EN 60079-0 comprises general regulations on the construction and testing of electrical equipment for use in explosion
General requirements EN 60079-0
hazardous areas.
Ignition temperature and classification of combustible
materials according to groups and temperature classes
In the case of ignition inside the encapsulation, the enclosure must withstand the pressure, and a transfer of the 1 (I = mining areas susceptible to fire damp II = all other atmospheres)

Flameproof enclosure (d) EN 60079-1
"inner" explosion to the outside must be ruled out. 2
450 °C Maximum surface temperature of apparatus

Presurised enclosure EN 60079-2 A protective gas, which is under overpressure, (min 0.5 mbar) encloses and separates the ignition source from the
2
(p) (pD2) (px) (py) (pz) EN 61241-4 surrounding atmosphere.

The finely grained material encloses the ignition source. An electric arc generated in the inside of the housing must not be 1 300 °C
Sand filling (q) EN 60079-5
capable of igniting the potentially explosive atmosphere during normal operation. 2

200 °C
Protection type „oil immersion“ implies that the electrical apparatus and its components are separated from the potentially 1
Oil immersion (o) EN 60079-6
explosive atmosphere by immersion in oil. 2

135 °C
100 °C
This protection type ( e ) applies only to electrical equipment and its components which is incapable of generating danger-
1 85 °C
Increased safety (e) EN 60079-7 ous sparks, electrical arcs or thermal effects during normal operation. The voltage rating of this type of equipment may not
2
exceed 11 kV.

0 T1 T2 T3 T4 T5 T6
The energy in the current circuit is limited to such an extent that sparks, electrical arcs or high temperatures cannot be
Intrinsic safety (ia) (ib) (ic) EN 60079-11 1 I Methane
generated.
2
IIA Aceton Butane Benzines
Ammonia Butanol Diesel
Sparking is excluded. Clearances and creepage distances are determined. Maximum surface and component temperatures Amyl Acetate Ethanol fuel
are limited. Benzene Hexane
Non sparking apparatus (nA) EN 60079-15 2
The protection degree of the housing has to be at least IP54/IP44. Acetic Acid
Area of application: zone 2. Ethane
Ethyl acetate
Carbon
The protection type applies to sparking equipment, in which contacts are appropriately protected by: monoxide
– enclosed switching device Methane
Sparking apparatus (nC) (nR) EN 60079-15 – enclosed i.e. sealed equipment 2 Methanol
– hermetically sealed housing. Propane
Area of application: zone 2. Toluene

20 IIB Town gas Ethylene Hydrogen Diethyl ether

Encapsulation Possible ignition sources are encapsulated in a potting material so that they are incapable of igniting an explosive sulphide
EN 60079-18 21
(m) (ma) (mb) (mc) atmosphere.
22 IIC Hydrogen Acetylene Carbon
disulphide

Distinguished are:
- certified intrinsically safe systems 0
Intrinsically safe electrical - certified intrinsically safe systems
EN 60079-25 1
systems (ia) (ib) (ic)
2
An intrinsically safe system is the approved assembly of interconnected electrical equipment (intrinsically safe and associ-
ated apparatus). It is documented accordingly in the system description.

Optical radiation
(op pr) (op sh)
EN 60079-28
The optical radiated power is limited so that it is incapable of igniting an explosive
atmosphere.
1
2
www.turck.com
Hans Turck GmbH & Co. KG
Witzlebenstr. 7
20 45472 Muelheim an der Ruhr
 Protection by housing The enclosure is so dense that no combustible dust can enter it. 21 Germany
EN 60079-31
(t2,) (ta) (tb) (tc) The surface temperature of the outer enclosure is limited. 22 Tel. +49 208 4952-0
Fax +49 208 4952-264
E-Mail more@turck.com
) Application in dust areas
2
D200457 2014/04_V1.2
Subject to change without notice ● Edition 04.14 ● © Hans Turck GmbH & Co. KG 2014