In many industrial and public industries, explosion hazards
are ever-present, e.g. the chemicals industry, refineries, on
drilling platforms, gas stations, feed manufacturing and sewage
The risk of explosion is always present when gases, fumes, mist or
dust are mixed with oxygen in the air in an explosive ratio close to
sources of ignition that are able to release the so-called minimum
In the chemical and petrochemical industries in particular, when
crude oil and natural gas are being transported, or in mining,
milling (e.g. grain and granular solids), explosion can result in
serious injury to persons and damage to equipment.
To ensure safety in these areas, legislators in most countries have
implemented appropriate stipulations in the form of laws and
regulations based on national and international standards.
Explosion-protected equipment is designed such that an explosion
can be prevented when it is used properly.
The explosion-protected equipment can be designed in
accordance with various types of protection.
The local conditions must be subdivided into specified zones
by the user with the assistance of the responsible authorities in
accordance with the frequency of occurrence of an explosion
hazard. Device (equipment) categories are assigned to these
zones. The zones are then subdivided into possible types of
protection and therefore into possible equipment (product) types.
Classification of zones
Areas subject to explosion hazard are divided into zones. Zoning is
based on the presence time of explosive substances and probability
of explosion. Information and specifications for classification of
the zones are laid down in the following standards:
• GB 3836.14, IEC/EN 60079-10-1 for gas atmospheres
• GB 12476.3, IEC/EN 60079-10-2 for dust atmospheres
Furthermore, a distinction is made between various explosion
groups as well as temperature classes and these are included in
the hazard assessment.
Depending on the particular zone and therefore the associated
hazard, operating equipment must comply with defined minimum
requirements regarding the type of protection. The different types
of protection require corresponding measures to prevent ignition
that should be implemented at the motor in order to prevent a
surrounding explosive atmosphere from being ignited.
The explosion-proof motors are often used in the following
industries to prevent explosion hazards that result in serious injury
to persons and severe damage to property.