| Class Ratings |
|
| Class I |
Hazardous environment containing flammable gases or vapors |
| Class II |
Hazardous environment containing combustible dust |
| Class III |
Hazardous environment containing ignitable fibers or flyings |
| Dision Ratings |
|
| Division 1 |
Hazardous material present under normal operating conditions |
| Division 2 |
Hazardous material present under abnormal conditions |
| Group Ratings |
|
| Group A |
Acetylene |
| Group B |
Hydrogen and gases of equivalent hazard |
| Group C |
Ethylene, propane, and gases of equivalent hazard |
| Group D |
Hydrocarbons, such as butane, gasoline, and methane, and gases of equivalent hazard |
| Group E |
Metal dusts, such as aluminum and magnesium |
| Group F |
Combustible carbonaceous dusts, such as coal and charcoal |
| Group G |
Grain dusts and other combustible dusts, such as flour and sugar |
| Zone Ratings |
|
| Zone 0 |
Hazardous material present continuously or for long periods of time in the form of gas or vapor in the atmosphere or in the work area |
| Zone 1 |
Hazardous material present intermittently or for short periods of time in the form of gas or vapor in the atmosphere or in the work area |
| Zone 2 |
Hazardous material present only under abnormal conditions, such as a leak or spill |
| Temperature Ratings |
|
| Temperature Code T1 |
Maximum equipment surface temperature of 450°F (232°C) |
| Temperature Code T2 |
Maximum equipment surface temperature of 300°F (150°C) |
| Temperature Code T3 |
Maximum equipment surface temperature of 200°F (100°C) |
| Temperature Code T4 |
Maximum equipment surface temperature of 135°F (57°C) |
| Temperature Code T5 |
Maximum equipment surface temperature of 100°F (38°C) |
| Temperature Code T6 |
Maximum equipment surface temperature of 85°F (30°C) |