Contents cont'd - hdbk109220040008

DOE-HDBK-1092-2004

5.1.6.7.4

ELECTRICAL TESTING INSTRUMENTS FOR USE WITH NONINITIATING

ELECTRICAL CIRCUITS ......................................................................................5-12

5.2

PREVENTION OF EXTERNAL IGNITION AND EXPLOSION ................................................5-12

5.2.1

SOURCES OF IGNITION ..............................................................................................5-13

5.2.2

COMBUSTION PRINCIPLES ........................................................................................5-14

5.2.3

EVALUATION OF HAZARDOUS AREAS .....................................................................5-14

5.2.4

INTRINSICALLY SAFE EQUIPMENT ...........................................................................5-14

5.2.5

ENCLOSURES ..............................................................................................................5-14

5.2.6

PURGING/PRESSURIZATION SYSTEMS ...................................................................5-16

5.3

HAZARDOUS LOCATIONS.....................................................................................................5-17

5.3.1

CLASS I .........................................................................................................................5-17

5.3.1.1

DIVISION 1 ................................................................................................................5-17

5.3.1.2

DIVISION 2 ................................................................................................................5-21

5.3.2

CLASS II ........................................................................................................................5-21

5.3.2.1

CLASS II DIVISION 1 ................................................................................................5-21

5.3.2.2

CLASS II DIVISION 2 ................................................................................................5-23

5.3.3

GROUPS........................................................................................................................5-23

5.3.4

IGNITION TEMPERATURE...........................................................................................5-23

5.3.5

FLAMMABLE (EXPLOSION) LIMITS ............................................................................5-23

5.3.6

FLASHPOINT.................................................................................................................5-24

5.4

ELECTRICAL EQUIPMENT FOR CLASS I, II, AND III AREAS ..............................................5-24

5.4.1

SEALS AND DRAINS ....................................................................................................5-24

5.4.1.1

SEALS .......................................................................................................................5-24

5.4.1.2

DRAINS .....................................................................................................................5-25

5.4.1.3

SELECTION OF SEALS AND DRAINS ....................................................................5-25

5.4.1.3.1

PRIMARY CONSIDERATIONS.............................................................................5-25

5.4.1.3.2

TYPES OF SEALING FITTINGS...........................................................................5-26

5.5

MANUFACTURERS' DIGEST..................................................................................................5-26

5.6

DESCRIPTIONS, FEATURES, AND TEST CRITERIA OF ENCLOSURES FOR

HAZARDOUS (CLASSIFIED) LOCATIONS (PER NEMA 250)...............................................5-27

5.7

TYPE 7 ENCLOSURES ...........................................................................................................5-27

5.7.1

DESCRIPTION AND APPLICATION .............................................................................5-27

5.7.2

FEATURES AND TEST CRITERIA ...............................................................................5-28

5.8

TYPE 8 ENCLOSURES ...........................................................................................................5-28

5.8.1

DESCRIPTION AND APPLICATION .............................................................................5-28

5.8.2

FEATURES AND TEST CRITERIA ...............................................................................5-28

5.9

TYPE 9 ENCLOSURES ...........................................................................................................5-29

5.9.1

DESCRIPTION AND APPLICATION .............................................................................5-29

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