Hazard Classifications

Class I Locations
Ignition Temperatures
Class II Locations
Quick Reference Charts

Hazardous locations are areas where fire or explosion hazards may exist due to the presence of flammable gases/vapors, flammable liquids, combustible dust, or ignitable fibers.

The type of hazard is defined as an “explosion hazard” in Class I and II locations, and a “fire hazard” in Class III locations. Materials do not have to be in the gaseous state for an explosion. Combustible dusts, and atomized liquids are other examples.

Class I Locations

Class I locations are areas in which flammable gases/vapors may be present in the air in quantities sufficient to produce explosive or ignitable mixtures:

Group A: acetylene
Group B: hydrogen, or gases/vapors of equivalent
Group C: ethyl ether vapors, ethylene or cyclopropane
Group D: gasoline, hexane, naptha, benzine, butane, benzol, lacquer solvent vapors, natural gas

Ignition Temperatures

The ignition temperature of a flammable material is critical in determining the acceptability of equipment/instrumentation that operates in hazardous locations as the external surface of the enclosure can act as an ignition source if the surface temperature exceeds the ignition temperature of the flammable material. High surface temperatures can result from normal operation of the equipment; abnormal operation (i.e. overheating); or because of a fault condition.

Equipment destined for installation in hazardous areas is marked with a code representing the maximum external surface temperature. Equipment cannot be used in hazardous areas when the maximum surface temperature is greater than the ignition temperature of the gases/vapors present.

Maximum Temperature	Identification Number
842°F	T1
572°F	T2
536°F	T2A
500°F	T2B
446°F (230°C)	T2C
446°F (215°C)	T2D
392°F	T3
356°F	T3A
329°F	T3B
320°F	T3C
275°F	T4
248°F	T4A
212°F	T5
185°F	T6

Class II Locations

Class II deals specifically with combustible dusts. The dust may be suspended in the air, in a cloud or in a layer on electrical equipment. The ignition temperature of a dust layer is usually lower than for a dust cloud.

Group E:
metal dusts (aluminum, magnesium and their alloys) and other combustible dusts whose particle size, abrasiveness and conductivity present similar hazard
Group F:
carbonaceous dusts (carbon black, charcoal, coal or coke) that have more than 8% total entrapped volatiles, or dusts sensitized by other materials so they present an explosion hazard
Group G:
atmospheres containing flour, starch or grain and combustible dust having a resistivity of 108 ohm-centimetre or greater as in grain elevators and bulk handling, flour, sugar, cocoa, spice grinding plants.

Quick Reference Charts

US HAZARD CODES Compared To ATEX HAZARD ZONES

GASES & VAPOURS

DUSTS

FIBRES

ATEX

Class I

Zone

Class II

Zone

Class III

Zone

Div 1

Div 2

Div 1

Div 2

Div 1

Div 2

GROUP A

II C

GROUP E

No Groups

Acetylene

Acetylene / Hydrogen

Conductive Dusts

Textiles / Woods

All Materials

GROUP B

II B

GROUP F

Hydrogen

Ethylene

Non conductive dusts

GROUP C

II A

Ethylene

Propane

GROUP D

Propane

ATEX		COMPARABLE HAZARD CODES FOR ATEX & US	US
zone	0	explosive gas / air mixture is continuously present	class I	div 1
zone	1	explosive gas / air mixture is likely to occur in normal operations	class I	div 1
zone	2	explosive gas / air mixture is not likely to occur	class I	div 2
zone	20	explosive dust atmosphere continuously present	class II	div 1
zone	21	explosive dust atmosphere occasionally present in normal operations	class II	div 2
zone	22	explosive dust atmosphere unlikely to occur	class III

Gases and Vapours : There are three zones for gases and vapours
ZONE 0			Flammable atmosphere highly likely to be present - may be present for long periods or even continuously.
ZONE 1			Flammable atmosphere possible but unlikely to be present for long periods.
ZONE 2			Flammable atmosphere unlikely to be present except for short periods of time - typically as a result of a process fault condition.
Zone 0 is the most DANGEROUS zone. It has the highest probability of a flammable atmosphere presence. Equipment for this zone must be very well protected against providing a source of ignition and have legal certification of this protection.
Dusts - There are three zones for dusts:
ZONE 20			Dust cloud likely to be present continuously or for long periods.
ZONE 21			Dust cloud likely to be present occasionally in normal operation.
ZONE 22			Dust cloud unlikely to occur in normal operation, but if it does, will only exist for a short period.
The likelihood of the dust layer being disturbed to create a cloud is important. Dust layers can make the equipment underneath it hotter then normal and create a more susceptible layer ignition temperature. It is mandatory for all products to be used in explosive and hazardous environments to have both the Ex and CE marking before being sold in the US and EU. All Industrial Vacuum C. C. products are legally certified with these compulsory markings.

Hazard Classifications

Industrial Vacuum products are all legally certified

Hazard Classifications

Class I Locations

Ignition Temperatures

Class II Locations

Quick Reference Charts

LET US HELP YOU SELECT THE VACUUM FOR YOUR NEEDS