Emerson Process Management GmbH & Co. OHG
1-3
1
Techn. Description
X-STREAM X2FD
Instruction Manual
HASXMDE-IM-EX
01/2015
1.4 High Pressure Option / Purge Option
1.4 High Pressure Option / Purge Option
Normally
fl
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
fl
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 in
fl
uences 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 X2FD 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:
Higher sample and calibration gas pres-
sures
Higher gas pressure is speci
fi
ed to be within
the range of 1100 hPa to 1500 hPa. The ma-
ximum permitted
fl
ow is 1,5 l/min, depending
on the installed measurement system lower
limits may apply.
The gas paths need additionally to be pro-
tected by suitable inline
fl
ame arrestors, de-
signed and approved for the applied higher
gas pressure and for the area of installation.
These
fl
ame arrestors need to be installed
outside the analyzer and in addition to the
fl
ame arrestors provided by the analyzer.
Note!
The external inline fl ame arrestors are not
subject of the analyzer certifi cation and may
be provided by the customer, or optionally by
EMERSON PROCESS MANAGEMENT.
A separate analyzer
fl
ame arrestor has to be
installed, operating as a breathing device and
thus limiting the increase of pressure in the
enclosure in case of internal leakage.
Purging the housing with clean gas when
measuring low concentrations
The maximum permitted gas
fl
ow is 2 l/min.
The gas must be supplied via a separate
fl
ame arrestor. Another
fl
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
for safe use given on the next
page!