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62
AO2000-LS25 LASER ANALYZERS | OI/AO2000-LS25-EN REV. D
... 10 Configuration, parameterization
... Description of menus and parameters
Some more specific units are also available such as %*m, ppm*m
and ppb*m. These units are often used for open path analyzers
and represent the concentration recalculated to 1 meter optical
path length.
Make sure that the actual optical path length is set to the correct
value in the "Measurement configuration" menu.
The primary unit used by the device to calculate the gas
concentration from the absorption line is the absolute unit
3
g/m
. All other units are calculated from this primary unit
assuming the ideal gas law is applicable.
3
The relative units g/Nm
, mg/Nm
obtained from the conversion of the absolute units (g/m
3
3
mg/m
and µg/m
) to standard pressure and temperature
assuming the ideal gas low. According to the European standard
that applies to the analyzer, these are the values P = 1.013 bar
and T = 0 °C.
Note that the US standard for the relative units g/Nm
3
mg/Nm
differs in respect of the standard temperature and is 25
°C.
Note that the gas concentration is always measured on "wet
basis", i.e. no correction is done for water vapor present in the
process gas.
Output format
The numerical format of the gas concentration on the LCD and in
most parts of the service program.
The format is presented according to the programming
language C (%6.2f means that the floating number will be
presented with 2 decimals and 6 digits including the decimal
point, e.g. 123.45).
Gas concentration in flanges, RU and TU
The gas concentrations in the flanges and in the RU & TU. The
unit can be chosen between g/Nm
dropdown list. If the measured gas is not present inside RU and
TU and/or in the flanges the corresponding gas concentration
must be set to zero.
Make sure that the appropriate optical path lengths are
specified in the "Measurement configuration" menu.
3
3
and µg/Nm
are the values
3
,
3
and
3
, % or ppm from the
Min/Max line position [0-63]
These values define the acceptance window (in samples) for the
line position in the second harmonic signal (see Second
harmonic signal <Second harmonic signal> on page 55). The
values cannot be modified if the program runs in User mode.
Reference line position
Specifies the position of the absorption line (in samples) in the
second harmonic signal. The value cannot be modified if the
program runs in User mode.
Max line position deviation
Specifies the maximum deviation of the line position (in
samples) from the reference line position. In case the deviation
is larger than the specified value the instrument will adjust the
laser temperature to bring the line back to the reference
position. The value cannot be modified if the program runs in
User mode.
Calibration constant
The constant used in calculation of the gas concentration. The
calibration constant is modified after calibration (see
Calibrating the device <Calibrate instrument> on page 63). The
value cannot be modified manually in this menu if the program
runs in User mode.
Line width constant
The constant used to calculate the line width, which in turn is
used to calculate the gas concentration. The line width constant
can be modified together with the calibration constant after
calibration (see Calibrating the device <Calibrate instrument>
on page 63). The value cannot be modified manually in this menu
if the program runs in User mode.
Line width measurement
This parameter switches the line width measurement function
ON and OFF. If switched OFF the theoretical line width for the
given gas pressure and temperature is used.
If switched ON the line width is measured from the shape of the
second harmonic absorption line. The value cannot be modified
manually in this menu if the program runs in User mode.
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