22 AO2000 CONTINUOUS GAS ANALYZERS | OI/AO2000-EN REV. B
Requirements of EN 60079-2 Annex D
• Temperature of protective gas at the inlet: If necessary, measures
should be taken to avoid condensation and freezing.
• If the compressor intake line passes through a hazardous area, it should
be constructed of non-combustible material and protected against me-
chanical damage and corrosion.
• Power for protective gas supply: The electrical power for the protective
gas supply (blower, compressor, etc.) should be either taken from a
separate power source or taken from the supply side of the electrical
isolator (e.g. disconnector) for the pressurized enclosure.
• The maximum pressure and flow of the flammable substance into the
containment system should not exceed the ratings specified by the
manufacturer (see section "Technical data" (see page 25)).
• The supply pressure of the sample gas and the protective gas must be
limited by the operator according to the maximum pressure values (see
section "Technical data" (see page 25)).
Requirements of EN 60079-14
• All ducts and their connecting parts shall be able to withstand a pressure
equal to 1.5 times the maximum overpressure, specified by the manufac-
turer of the pressurized equipment, for normal operation: Sample gas
supply 3 hPa × 1.5 = 4.5 hPa, purge gas supply 50 hPa × 1.5 = 75 hPa.
• The materials used for the ducts and connecting parts shall not be ad-
versely affected by the specified protective gas nor by the flammable
gas or vapors in which they are to be used.
• Ducting should be located in a non-hazardous area as far as is reasona-
bly practicable.
• Ducts for exhausting the protective gas should preferably have their
outlets in a non-hazardous area.
• If the internal pressure or flow of protective gas falls below the minimum
prescribed value, the loss of pressure is signaled by an error status at the
digital output (see analyzer data sheet). It must be ensured that this
signal is indicated in a manner that it is immediately apparent to the op-
erator. The pressurization system shall be restored as soon as possible,
or else the electrical supply shall be switched off manually.
• The predefined minimum pre-purge time for the pressurized volume of
the analyzer comprises the pipelines within the gas analyzer. The purg-
ing time shall be extended by the time required to purge the free volume
of the connected pipes (supply pipes) which are not part of the device
with at least five times their volume at the lowest flow rate of 15 l/h.
• Care should be taken to keep the temperature of the protective gas
below 40 °C at the inlet of the enclosure.
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