OSHA
Regulations
HMI Hoist Duty Classifications
NEMA Standards
Beam Dimensions
Explosion Proof Classifications
Full Load Amp Chart/Temp
Ratings
CMAA Crane Duty
Classifications
IEC Enclosure Ratings
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Explosion classified
areas are defined by the following classes, divisions and groups, by the
National Electric Code (NEC) (*See caution below). Many hoist manufacturers
can furnish equipment to comply with the various classifications. A distinction
needs to be recognized between equipment designed to comply with these
provisions of the NEC and equipment that is designed to be spark resistant.
The provisions of the NEC are related primarily to the use of proper enclosures
and wiring trolleys, bronze hooks, stainless steel chain or wire rope
to accomplish the necessary spark resistance. When specifying equipment
for these areas please determine if you need spark resistant features
in addition to the NEC requirements for the electrical enclosures and
wiring. Spark resistant features when applied to hoist equipment normally
decrease the capacity and increase the cost.
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Explosion
Proof Classifications
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Class
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Definitions
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Class
I
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Locations:
Are those in which flammable gases or vapors are or may be present
in the air in quantities sufficient to produce explosive or ignitable
mixtures. |
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Class
II
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Locations:
Are those which are hazardous due to the presence of combustible dust. |
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Class
III
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Locations:
Are those which are hazardous due to the presence of easily ignitable
fibers or flyings, but in which such fibers or flyings are not likely
to be in suspension in the air in quantities to produce ignitable
mixtures. |
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Division
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Division
I
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Locations
in which hazardous concentrations in the air exist continuously, intermittently,
or periodically under normal operating conditions. |
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Division
II
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Locations
in which hazardous concentrations are handled, processed, or used
but are normally within closed containers or closed systems from which
they can escape only in case of accidental rupture or breakdown. |
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Group
(Class I)
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Group
A
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Atmospheres containing acetylene. |
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Group
B
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Atmospheres
containing hydrogen, or gases (or vapors) of equivalent hazard, such
as manufactured gas. |
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Group
C
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Atmospheres
containing ethyl-ether vapors, ethylene or cyclo propane. |
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Group
D
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Atmospheres
containing gasoline, hexane, naptha, benzine, butane, alcohol, acetone,
benzol, lacquer solvent vapors, or natural gas. |
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Group
(Class II)
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Group
E
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Atmospheres
containing metal dust, including aluminum, magnesium and their commercial
alloys and other metals of similarly hazardous characteristics. |
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Group
F
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Atmospheres
containing carbon black, coal, or coke dust. |
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Group
G
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Atmospheres
containing flour, starch, or grain dust. |
*Caution: Please consult
the National Electric Code for the exact requirements.
The above breakdown is a summary and should not be relied upon for accuracy
or completeness.
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