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Emerson Process Management GmbH & Co. OHG 1-3
1
Techn. Description
X-STREAM XEFD
Instruction Manual
HASXEDE-IM-EX
03/2012
1.4 High Pressure Option / Purge Option
1.4 High Pressure Option / Purge Option
Normally ameproof housings are permitted
to operate under atmospheric conditions only,
that is within an ambient pressure range bet-
ween 800 and 1100 hPa.
For analyzers this pressure range also applies
to the gas pressure within the containment
system. While the lower limit is not critical,
the higher is, because it lowers the permitted
sample gas (and calibration gases) pressures
by 400 hPa, compared to general purpose
analyzers. This results in higher requirements
for the sample handling system, as it has to
safely reduce the process gas pressure to the
permitted range.
Another aspect to take care for when ope-
rating ameproof analyzers is the option of
applying a purge gas to the enclosure when
measuring low concentrations of gases, being
constituent of the ambient air: The ambient air
inside the analyzer enclosure cross interfe-
rese with the sample gas and inuences the
measuring results. By purging the housing
with a gas free of the measured component,
this can be avoided, but could increase the
pressure inside the analyzer and so would
violate the atmospheric pressure condition.
X-STREAM ameproof analyzers have been
subjected to additional tests to support both
situations:
• higher sample and calibration gas pres-
sures
as well as
• purging the housing with a gas for best
measuring results at low concentrations.
To permit this, special additional conditions
must be taken into account:
High sample and calibration gas pressures
Higher gas pressure is specied to be within
the range of 1100 hPa to 1500 hPa. The maxi-
mum permitted ow is 1,5 l/min, depending on
the installed measurement system lower limits
may apply.
The gas paths need additionally to be protected
by suitable inline ame arrestors, designed and
approved for the applied higher gas pressure
and for the area of installation. These ame ar-
restors need to be installed outside the analyzer
and in addition to the ame arrestors provided
by the analyzer.
Note!
The external inline flame arrestors are not
subject of the analyzer certication and may
be provided by the customer, or optionally by
EMERSON PROCESS MANAGEMENT.
A separate analyzer ame arrestor has to be
installed, operating as a breathing device and
so limiting the increase of pressure in the en-
closure in case of internal leakage.
Purging the housing with clean gas when
measuring low concentrations
The maximum permitted gas ow is 2 l/min. The
gas must be supplied via a separate ame ar-
restor. Another ame arrestor must be installed,
operating as a breathing device and so limiting
the increase of pressure in the enclosure.
EXPLOSION HAZARD
When making use of any of above
mentioned options, take care
of the special conditions given
in the technical data section,
and in chapter 2 (installation
instructions)!