Servomex SERVOTOUGH LaserExact 2950, Руководство оператора

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SERVOTOUGH LaserExact Monitor, Operator Manual 02950001A_1
SERVICE PROGRAM
33
where N is the originally measured gas concentration on wet basis and H
2
O(%) is
the input H
2
O concentration in % vol. The factor that multiplies N is Dry conversion
factor which can be monitored in the Measurements menu .
H
2
O input method
The following input methods for the H
2
O concentration can be selected: Fixed,
Current loop, Measured, Calculated.
Method “Fixed” sets the H
2
O concentration equal to the manually specified value.
With method “Current loop” the H
2
O concentration is input from an external H
2
O
sensor via the Extra (Flow) current input. In this case Extra (flow) current input
select must be set to “Gas-unit”, where “unit” corresponds to the output
concentration unit of the external H
2
O sensor. The 4 and 20 mA values must be
specified. Method “Measured” can be used when the SERVOTOUGH Laser
monitor is configured to measure several gases and one of them is H
2
O. The
maximum H
2
O concentration used for dry basis conversion with this method is
limited to 50% vol. If the measured concentration exceeds this value the value
used for dry basis conversion will still be 50% vol. When method “Calculated” is
selected, the instrument calculates saturated water vapour concentration based on
the gas temperature and pressure input values. The calculated H
2
O concentration
is then used for dry basis conversion. The maximum gas temperature for this
method is about 90°C and the maximum calculated H
2
O concentration is limited to
70% vol. The same H
2
O limit is used also for “Fixed” and “Current loop” methods.
4.3.6 Gas specific parameters
If the instrument monitors more than one absorption line a selection menu with the
relevant gases appears first.
Upon selection of one gas the following menu is displayed:
Measured gas
Displays the gas type. Cannot be modified if the program runs in User mode.
Unit
Select the appropriate unit for output of the gas concentration from the dropdown
list.
The units may be grouped in two different categories, the absolute units:
g/m
3
,
mg/m
3
and ug/m
3
( ug refers to micrograms) and the relative units: %, ppm, ppb,
g/Nm
3
, mg/Nm
3
and ug/Nm
3
.
Some more specific units are also available such as %*m , ppm*m and ppb*m .
These units are often used for Open Path SERVOTOUGH Laser monitors and
represent the concentration recalculated to 1 meter optical path length. Note that
the actual path length in
Measurement configuration menu should nevertheless
be set to the correct value.
The primary unit used by the instrument to calculate the gas concentration from
the absorption line is the absolute unit
g/m
3
. All other units are calculated from this
primary unit assuming the ideal gas law is applicable.