24 AO2000 CONTINUOUS GAS ANALYZERS | OI/AO2000-EN REV. B
Internal and external explosion protection
No release of flammable sample gas
A release of flammable sample gas from the sample gas path ("containment
system") into the system housing is reliably prevented by the following
measures:
• The sample gas paths of the analyzer module are technically sealed,
connected by metal tubes and tested for seal integrity.
• The sample cell of the Uras26 Analyzer Module is designed to be fail-safe
(with the exception of windows and seals). Connection pipes and sam-
ple cell are metallic, welded to each other and routed from the system
housing without additional cable glands.
• A gas purge curtain encloses all the parts of the sample gas path which
are not fail-safe, e.g. windows or seals. It is designed in pressurized en-
closure type "py". When operated in accordance with the technical data
(see page 25), the purging gas pressure is usually at least 0.5 hPa above
sample gas pressure. In this way, the sample gas path meets the basic
requirements for "no release" as specified in EN 60079-2:2005, Section
11.1.
• At appropriate intervals the sample gas pressure and function of the
pressurized enclosure are checked.
• At appropriate intervals the sample gas path and purge gas path are
checked for leak tightness.
Remark: The term "purging gas" is used in the sense of "inert gas" in accord-
ance with EN 60079-2.
No electrical ignition sources in the system housing
The electrical components in the system housing are non-arcing assemblies
and components or "sealed devices" as per EN 60079-15. Thus there are no
electrical ignition sources in the system housing during normal operation.
If sample gas is released in spite of the measures described above and a
dangerous explosive atmosphere forms briefly inside the system housing,
explosion protection is nevertheless assured.
No ignition sources in the sample gas path
There are no ignition sources in the sample gas path during normal opera-
tion.
External explosion protection
Only non-hot assemblies and components are located inside the system
housing.
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