Ex Protection

Ignition sources

Classification of Ignition Sources for gas and vapour

Hot surfaces

Ignition temperature
  Sparks

Ignition

Energy
Temperature Class

T1 ... T6
Gas Group

A ... C

Temperatur Class

Temperatur class Maximum surface temperature
(at max. ambient temperature)
T1 450C
T2 300C
T3 200C
T4 135C
T5 100C
T6 85C

Energy Classification

Minimum Ignition Energy European Groups USA/Canada Groups Gas e.g.
< 20 Joules C A Acetylene, Carbon disulphide
< 20 Joules B Hydrogen
< 60 Joules B C Ethylether, Ethylene
< 180 Joules A D Acetone, Butane, Ethanol, Gasoline, Hexane, Methanol, Methane, Naphtha, Propane

Standards valid for Electrical Apparatus for Explosive Gas Atmospheres

  EN (old) EN (new)
General requirements EN 50014 EN 60079-0
Flameproof enclosures "d" EN 50018 EN 60079-1
Pressurized enclosures "p" EN 50016 EN 60079-2
Powderfilling "q" EN 50017 EN 60079-5
Oil immersion "o" EN 50015 EN 60079-6
Increased safety "e" EN 50019 EN 60079-7
Intrinsic safety "i" EN 50020 EN 60079-11
Type of protection "n" EN 50021 EN 60079-15
Encapsulation "m" EN 50028 EN 60079-18
Intrinsically safe systems EN 60079-25
Electrical equipment for Zone 0 EN 50284 EN 60079-26
Intrinsically safe field bus systems EN 60079-27
Optical radiation "op" EN 60079-28

Standards valid for electrical apparatus for Explosive dust atmosphere

Standard EN (IEC) Protection name Protection method
61241-0 General requirements for Dust equipment
61241-1 / 60079-31 tD Protected by enclosures
61241-2 pD Protected by pressurization
61241-11 iD Protected by intrinsic safety
61241-18 mD Protected by encapsulation

Standards valid for mechanical equipment

Protection type EN 13463- Marking letter
Construction EN 13463-5 c
Inherent safety EN 13463-4 g
Flow restriction EN 13463-2 fr
Pressurization EN 13463-7 p
Flameproof EN 13463-3 d
Controlled ignition EN 13463-6 b
Protected by oil EN 13463-8 k

Combustion motors

EN 1834-1 Gas, group II
EN 1834-2 Gas, group I
EN 1834-3 Dust, group III

Explosive Atmosphere

Atex Directive

Ignition Sources

Basic Electrical Techniques

Equipment Protection Level

IP-Rating