| Grouping
of Electrical Apparatus for Potentially Explosive Atmospheres
|
|
Group I Electrical apparatus for Mining,
typified by the gas Methane (Firedamp)
Group II Electrical apparatus for surface industries
Group II may be further divided
into three gas groups :
IIA - Representative Gas Propane
IIB - Representative Gas Ethylene
IIC - Representative Gas Hydrogen
Gas Group IIC covers the most hazardous gases and as
such, apparatus marked IIC may be used in group IIA
and IIB applications.
|
| Classification
of Hazardous Areas |
Zone 0 - Area in which a potentially explosive atmosphere
is constantly present, or present for long periods.
(Rough guide : hazard present for more than 1000 hours/year).
Zone 1 - Area in which a potentially explosive atmosphere
is likely to occur in normal operation.
(Rough guide: hazard present between 10 & 1000 hours/year).
Zone 2 - Area in which a potentially explosive atmosphere
is not likely to occur in normal operation and if it occurs
it will exist only for a short time.
(Rough guide: hazard present for less than 10 hours/year).
Guidance in the classification of hazardous areas is given
in EN 60079-10, IEC 60 079-10, Institute of Petroleum
Code
Part 15, API 505, NFPA 497 |
| Methods
of protection permitted in desigated hazardous areas |
|
Zone
|
Type of protection permitted |
European Standard Number |
|
0
|
EEx ia - intrinsically safe
apparatus or system
|
EN50020, EN50039 |
|
1
|
Any type of
protection suitable for Zone 0
EEx d - flameproof enclosure
EEx ib - intrinsically safe apparatus or system
EEx p - pressurised apparatus
EEx e - increased safety
EEx m - encapsulation
EEx o - oil immersion
EExq - powder filing |
EN50018
EN50020, EN50039
EN50016
EN50019
EN50028
EN 50015
EN 50017 |
|
2
|
Any type of protection suitable for Zone
0 and/or Zone 1
EEx n - non-sparking |
'EN' In course of preparation.
(pr EN50021)
|
Information on the design,
selection and erection of electrical installations in
explosive gas atmospheres is given in
EN 60079-14 , IEC 60079-14. |
