Teledyne API Model M201E NH3 Analyzer Operator Manual | M201E Ammonia Analyzer |
and registered as NOx. 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
TNx (Total Nitrogen) Concentration = Measured (NH3 + N02 + NO)
NOx (Total Nitrogen – Ammonia) Concentration = Measured (NO2 + NO) NH3 (Ammonia) Concentration = Calculated as follows:
[(TNx - NOx) / (NH3_CE_FACTOR1)]
NO2 (Nitrogen Dioxide) Concentration = Calculated as follows:
[(NOx – NO) / (NO2_CE_FACTOR1)]
Note: The nitrogen dioxide efficiency factor (NO2_CE_FACTOR1) must be calculated by conducting a GPT (gas phase titration) as described in Section
8.3.3of 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 (NH3_CE_FACTOR1) is discussed in more detail in Section 2.3 of this manual. The conversion efficiency of the M501 NH3, 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 (TNx, NOx, 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.
1.1.1Minimizing 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
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