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The IECEx scheme is an international certication
scheme for products which meet the requirements of the
international standards, e.g. the technical committee TC31’s
IEC standards.
The certicates awarded in this scheme are published on the
IECEx website (www.iecex.com) as an electronic certicate.
They can be viewed online and printed out.
A Certicate of Conformity (CoC) refers to a test report
(ExTest Report ExTR) and on an assessment of the quality
assessment report from the manufacturer (QAR).
The standards used for the production of the test report
correspond almost entirely to the harmonised standards
in Europe. Recent EN standards were initially adopted as
IECstandards.
Protection concepts
The zoning described above provides the basis for the
selection of the type of ignition protection. So, as an
example, in the ATEX applicable areas, only ignition
protection devices meeting Ex ia for Zone 0 (highest
probability of an explosive atmosphere being present) are
allowed.
Increased safety Ex e
No sparks and a surface temperature limited
to a safe level
Increased safety is for products where there
are no sparks produced during normal
operation or in case of a failure. The surface
temperature of the relevant parts is limited
to a value below the ignition temperature.
Increased safety is achieved by reducing the current load
and raising the isolation properties and by maintaining
clearance and creepage distances above the value in an
industrial application. The highest voltage permitted for this
protection scheme is 11 kV (D.C. or A.C. rms).
This protection scheme is usually used for distribution
cabinets..
Intrinsically safe Ex i
Limited to a safe level of ignition energy
Intrinsic safety is for products where
electrical energy which ows into the
product, or is stored in the product, is not
sufcient to ignite the surrounding explosive
atmosphere. This also applies in fault
conditions. The methods that achieve intrinsic safety mean
that it is important that not only the devices installed in
direct contact with the explosive atmosphere are
constructed correctly, but also the electrical devices to
which they are connected.
Intrinsically safe equipment and intrinsically safe parts of the
associated equipment are divided into protection levels: ia
(for zones 0, 1, and 2), ib (for zones 1 and 2), and ic (only for
zone 2).
A typical application area are control and display circuits
with low voltage and current.
Pressure-resistant Ex d encapsulation
Limits the explosion to the inside of the enclosure
Pressure-resistant encapsulated enclosures
are designed for devices where sparks are
generated or which have hot surfaces which
are a source of ignition during normal
operation. Similarly, industrial components
for use in potentially explosive atmospheres are often made
suitable by encapsulating them in a pressure-resistant
enclosure which otherwise could not be used.
The surrounding possibly explosive atmosphere can enter
the enclosure and will produce an internal explosion during
the equipment’s lifespan.
The enclosure must therefore be stable enough to ensure
that it is not deformed or destroyed by the pressure created.
All connections of the enclosure are sized so that they
cannot transmit an explosion from inside to the surrounding
atmosphere. These connections are known as ignition gaps.
IECEx scheme
IECEx scheme
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Technical appendix
2712630000