Explosion protection - What does this mean?
What is explosion protection?
Operational facilities or areas where a sufficient quantity of inflammable substances comes in contact with oxygen (air) are
classified as hazardous areas. Here, measures must be implemented to eliminate the risk of ignition caused by electrical or
mechanical operating equipment (devices, tools, machines and/or vehicles).To avoid explosion hazards caused by sources
of ignition, "explosion-proof" operating equipment must be used if required.
ATEX-symbol
Types of protection:
"Degrees of protection" for operating equipment, e.g. "flameproof enclosure", "increased safety", "powder filling" or
"restricted breathing enclosure", have been specified in the national set of standards, which all provide equal
levels of protection against the risk of ignition.
Zone classification:
Hazardous areas are divided into zones. Depending on the extent of explosive atmosphere, the zones for gases,
vapours, mists are as follows:
| Zone 0 |
(category 1G *): |
permanently, long-time or frequently |
| Zone 1 |
(category 2G *): |
occasionally |
| Zone 2 |
(category 3G *): |
rarely and short-time |
* = device category in accordance with the new directive 94/9/EG - "ATEX"
Explosion groups:
Explosive gases and vapours are divided into the following explosion groups:
| IIC: |
e.g. hydrogen, acetylene, carbon disulphide |
| IIB: |
e.g. natural gas, ethylene |
| IIA: |
all other gases |
Temperature classes:
Depending on the ignition temperature, flammable gases and vapours are divided into temperature classes.
The maximum surface temperature of electrical operating equipment must always be lower than the respective ignition temerature.
| T6 |
< |
85 °C |
|
| T5 |
< |
100 °C |
|
| T4 |
< |
135 °C |
|
| T3 |
< |
200 °C |
|
| T2 |
< |
300 °C |
|
| T1 |
< |
450 °C |
|
Information on the permissible temperature class for the planned application area can be obtained from the local labour inspectorate.
Responsiblility of the user:
Responsible co-operation of planner, plant constructor and operator is essential for an efficient explosion protection. This includes
a careful selection of operating equipment, operation of the equipment in accordance with the permissible purpose and proper
assembly, installation and commissioning. A proper condition of the explosion protection can be maintained by means of repeated
inspections of the operating equipment and the plant.