UFC 3 -520-01
June 10, 2002
Table 8-5. Hazardous Location Classifications
Class
Group
Examples
I
A
Acetylene
I
B
Hydrogen, manufactured gas
I
C
Ethyl ether, ethylene, cyclopropane
I
D
Jet fuel, gasoline, hexane, butane, naphtha, propane,
acetone, toluene, isoprene
II
E
Metal dust
II
F
Carbon black, coal dust, coke dust
II
G
Flour, starch, grain dust
8-3.2
Referring to Table 8 -5, a Class I location contains flammable gases or vapors
that might be present in air in sufficient quantities to produce explosive or ignitable
mixtures. Class I locations are further subdivided into Division 1 and Division 2, as
described below.
8-3.3
In accordance with NEC Article 500.5 (2002 Edition) , a Class I, Division 1
classification applies to the following types of locations.
Locations in which ignitable concentrations of flammable gases or vapors can exist
under normal operating conditions .
Locations in which ignitable concentrations of such gases or vapors might frequently
exist because of repair or maintenance operations or because of leakage.
Locations in which breakdown or faulty operation of equipment or processes might
release ignitable concentrations of flammable gases or vapors, and might also cause
simultaneous failure of electrical equipment in such a way as to directly cause the
electrical equipment to become a source of ignition.
8-3.4
In accordance with NEC Article 500.5 (2002 Edition) , a Class I, Division 2
classification applies to the following types of locations.
Locations in which volatile flammable liquids or flammable gases are handled,
processed, or used, but in which the liquids, vapors, or gases will normally be
confined within closed containers or closed systems from which they can escape
only in cases of accidental rupture or breakdown of such containers or systems, or in
case of abnormal operation of equipment.
Locations in which ignitable concentrations of gases or vapors are normally
prevented by positive mechanical ventilation, and which might become hazardous
through failure or abnormal operation of the ventilating equipment.
8-9
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