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Teledyne API Model M201E NH
3
Analyzer Operator Manual M201E Ammonia Analyzer
05206H DCN5910 11
and registered as NO
x
. This location provides the drier with continuous flow,
thereby allowing it to stabilize faster.
Note: Due to the Nafion® drier, the analyzer has a maximum ammonia range of
2.0 PPM.
The calculated gas concentrations, ammonia and nitrogen dioxide, are computed
from the differences between the measured channels, as outlined in the following
equations:
NO (Nitric Oxide) Concentration = Measured
TN
x
(Total Nitrogen) Concentration = Measured (NH
3
+ N0
2
+ NO)
NO
x
(Total Nitrogen – Ammonia) Concentration = Measured (NO
2
+ NO)
NH
3
(Ammonia) Concentration = Calculated as follows:
[(TNx - NOx) / (NH
3
_CE_FACTOR1)]
NO
2
(Nitrogen Dioxide) Concentration = Calculated as follows:
[(NOx – NO) / (NO
2
_CE_FACTOR1)]
Note: The
nitrogen dioxide efficiency factor (NO
2
_CE_FACTOR1) must be
calculated by conducting a GPT (gas phase titration) as described in Section
8.3.3 of the M200E manual and Section 7.0 of this manual. This value gives a
good indication of how well the molybdenum is converting nitrogen dioxide into
nitric oxide. In a properly functioning analyzer the value should be close to 1.0. It
is recommended that the molybdenum efficiency be checked every three months.
The ammonia converter efficiency factor (NH
3
_CE_FACTOR1) is discussed in
more detail in Section 2.3 of this manual. The conversion efficiency of the M501
NH
3
, should be checked prior to starting long term tests. Both efficiency factors
can be accessed through the analyzer VARS MENU.
The actual formula for computation of the gas concentrations is more
complicated than the above equations, as it includes sample, reaction cell
pressure changes and averaging the PMT signal. Then the zero offset and
slopes are applied to the separate channels (TN
x
, NO
x
, NO) to determine the
concentrations. Concentration compensation occurs while the variable
TP_FACTOR under the VARS MENU is switched ON. Otherwise the displayed
concentration is uncompensated. It is recommended that the variable
TP_FACTOR remain on at all times.
1.1.1 Minimizing PMT Drift
In order to account for PMT drift in the analyzer, the AutoZero valve switches
once a minute allowing the analyzer to read zero background. The AutoZero
valve directs the sample gas stream to completely bypass the reaction cell, while
simultaneously filling the reaction cell with Ozone for dark noise measurement.
This is then subtracted as a measurement offset from the raw PMT concentration