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Emerson Process Management GmbH & Co. OHG7-10
X-STREAM XE
Instruction Manual
HASXEE-IM-HS
10/2010
Fig. 7-2: Calibration Improvement by Variable Valve Assignments
7.4.1.1 Valve Assignment for Valve Supported Calibrations
7.4.1 Preparing Calibrations
As described earlier, several calibration
procedures require installed internal and/or
external valves.
In addition this requires all requested cali-
bration gases to be connected to the valves
and the valves to be software assigned to
the gases.
Why is assigning valves required?
For such calibrations the analyzer controls the
gas ow and therefore needs to 'know' about
the different valve functions - this is done by
valve assignment.
In addition variable valve assignment allows
to use one valve for different functions.
Example:
• Dual channel analyzer for measuring CO
and CO
2
.
• Span gases are CO and CO
2
, zero gas
for both channels is N
2
.
Without variable assignment one would need
to zero span channel 1 separately from channel
2. Taking into account the purge times before
a calibration calculation starts, to ensure the
measuring cells are lled with calibration gas,
the whole procedure would take a quite long
time.
With variable valve assignment the operator
can specify e.g. the valve V1 to be the zero
gas valve for channel 1 AND channel 2.
Now, when starting a zero calibration, the
analyzer calculates the zero values for both
channels at a time!
Zero spanning with
xed assignment
Zero spanning with
variable assignment
purge times
calibration
ch1 ch1 ch1 ch2 ch2 ch2
ch1
&
ch2
ch1 &
ch2
ch1
&
ch2
improvement in
time
timeline