wtw TresCon NOx-N, Руководство по эксплуатации

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Operation NOx-N
2 - 12 ba43110e05 01/2011
2.7 Manual correction
The background color is newly determined and calculated each time
the measuring value is updated.
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The TresCon NOx-N uses internally stored standard values to
suppress the background color.
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These standard values provide complete suppression of the
background colors for the majority of all wastewater treatment
plants.
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You can also adapt the TresCon NOx-N to special conditions
(manual correction).
In some cases, manual correction of the internal standard values for
background correction may be required. This is the case if the
measured value of the TresCon shows deviations > 7 % of the
measuring range final value in comparison with laboratory
photometers.
Note
Manual correction (input of Cnominal) is only possible if the TresCon
NOx-N has performed at least one measurement.
Principle The concentration of NOx is - at the same time and place as possible
- measured in a representative sample using a selected comparison
procedure (e. g. a laboratory photometer and WTW reaction cell test)
and the TresCon NOx-N. The measured value from the comparison
procedure is entered as the nominal value for TresCon NOx-N. From
the nominal value and its own measured value, TresCon calculates a
correction factor h that is used for all further measurements.
Note
Manual correction is only possible within physically sensible limits.
When Cnom is input, the analyzer checks whether the correction is
possible and calculates the optimum background correction.
Process instructions for
the comparison
measurement using a
laboratory photometer
For sampling and measurement, perform the following steps:
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Open the overflow vessel of the TresCon NOx-N.
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Using a pipette, carefully take the required amount of sample for the
comparison measurement. Make sure no sediment is dispersed and
sucked in. The level of the liquid should not sink below the catch
point of the sample (fitting of the sample tube).
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Close the overflow vessel of the TresCon NOx-N.
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Immediately afterwards start a measuring procedure on the
TresCon NOx-N.