
Definitions: Flammable and Combustible Gases and Vapors
Equipment Protection Techniques
The following definitions describe some of the most common terms used in flammable and
combustible gases and vapors protection techniques listed in Tables 9.9, Table 9.13, and Table
9.14. Some definitions are only applicable to those equipment protection techniques utilized in
TABLE 9.7 Zone classification equipment protection techniques
Protection technique Suitable hazardous (classified) area locations
Flameproof ‘‘d’’ Class I, Zone 1 or 2
Purged and Pressurized Class I, Zone 1 or 2
Intrinsic Safety Class I, Zones 0, 1, or 2 (as listed)
Type of Protection ‘‘n’’ Class