Klasifikace nebezpečných oblastí - Severní Amerika

Třída I

Hazardous because flammable gases or vapors are present (or may be present) in quantities sufficient to produce explosive or ignitable mixtures.

Třída II

Hazardous because combustible or conductive dusts are present (or may be present) in quantities sufficient to produce explosive or ignitable mixtures.

Třída III

Hazardous because ignitable fibers or flyings are present (or may be present) in quantities sufficient to produce explosive or ignitable mixtures.

Divize 1

The substance referred to by class has a high probability of producing an explosive or ignitable mixture due to it being present continuously, intermittently, or periodically or from
the equipment itself under normal operating conditions.

Divize 2

The substance referred to by class has a low probability of producing an explosive or ignitable mixture and is present only during abnormal conditions for a short period of time - such as a container failure or system breakdown

Skupina A

Atmosphere containing acetylene.

Skupina B

Atmosphere containing a flammable gas, a flammable liquid produced vapor, or a combustible liquid produced vapor mixed with air that may burn or explode, having either a MESG (Maximum Experimental Safe Gap)¹⁾ value less than or equal to 0.45 mm or a MIC (Minimum Igniting Current)²⁾ ratio less than or equal to 0.40 - such as hydrogen or fuel and combustible process gases containing more than 30% hydrogen by volume - or gases of equivalent hazard such as butadiene, ethylene oxide, propylene oxide and acrolein.

Skupina C

Atmosphere containing a flammable gas, a flammable liquid produced vapor or a combustible liquid-produced vapor whose MESG is greater than 0.75 mm or MIC ratio is greater than 0.40 and less than 0.80 - such as carbon monoxide,ether, hydrogen sulfide, morphline, cyclopropane, ethyl, isoprene, acetaldhyde and ethylene or gases of equivalent hazard.

Skupina D

Atmosphere containing flammable gas, flammable liquid produced vapor, or combustible liquid produced vapor mixed with air that may burn or explode, having either a MESG value greater than 0.75 mm or a MIC ratio greater than 0.80 - such as gasoline, acetone, ammonia, benzene, butane, ethanol, hexane, methanol, methane, vinyl chloride, natural gas, naphtha, propane or gases of equivalent hazard.

Skupina E

Atmosphere containing combustible metal dusts, including aluminum, magnesium, bronze, chromium, titanium, zinc and their commercial alloys or other combustible dusts whose particle size, abrasiveness and conductivity present similar hazards in connection with electrical equipment.

Skupina F

Atmosphere containing carbonaceous dusts, carbon black, coal black, charcoal, coal or coke dusts that have more than 8% total entrapped volatiles or dusts that have been sesitized by other materials so they present an explosion hazard.

Skupina G

Atmosphere containing combustible dust not included in Group E & F - such as flour, grain, starch, sugar, wood, plastics and chemicals.

0 Zone

Ignitable concentrations of flammable gases or vapors which are present continuously or for long periods of time.

1 Zone

Ignitable concentrations of flammable gases or vapors which are likely to occur under normal operating conditions.

2 Zone

Ignitable concentrations of flammable gases or vapors which are not likely to occur under normal operating conditions and do so only for a short period of time.

20 Zone

An area where combustible dusts or ignitable fibers and flyings are present continuously or for long periods of time.

21 Zone

An area where combustible dusts or ignitable fibers and flyings are likely to occur under normal operating conditions.

22 Zone

An area where combustible dusts or ignitable fibers and flyings are not likely to occur under normal operating conditions and do so only for a short period of time.

Skupina I

Mines
susceptible to firedamp (flammable mixture of gases naturally occurring in a mine).

Skupina II

Explosive gas
atmosphere other than mines susceptible to firedamp. Group II equipment is subdivided into three subgroups.

A

Atmospheres containing propane, acetone, benzene, butane, methane, petrol, hexane, paint solvents or gases and vapors of equivalent hazard.

B

Atmospheres containing ethylene, propylene oxide, ethylene oxide, butadiene, cyclopropane, ethyl ether, or gases and vapors of equivalent hazard.

C

Atmospheres containing acetylene, hydrogen, carbon disulphide or gases and vapors of equivalent hazard.

Skupina III

Explosive dust
atmosphere. Group III equipment is subdivided into three subgroups.

A

Atmospheres containing combustible flyings.

B

Atmospheres containing non-conductive dust.

C

Atmospheres containing conductive dust.