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PRINCIPLES OF OPERATION
6.
The T200 Nitrogen Oxides Analyzer is a microprocessor controlled instrument that
determines the concentration of nitric oxide (NO), total nitrogen oxides (NO
NO and NO
•
It requires that sample and calibration gases be supplied at ambient atmospheric
pressure in order to establish a constant gas flow through the reaction cell where the
sample gas is exposed to ozone (O
(hv).
•
The instrument measures the amount of chemiluminescence to determine the amount
of NO in the sample gas.
•
A catalytic-reactive converter converts NO
the NO present in the sample is reported as NO
between NO
Calibration of the instrument is performed in software and usually does not require physical
adjustments to the instrument. During calibration, the microprocessor measures the sensor
output signal when gases with known amounts of NO or NO
results in memory. The microprocessor uses these calibration values along with the signal
from the sample gas and data of the current temperature and pressure of the gas to calculate
a final NO
The concentration values and the original information from which it was calculated are
stored in the unit's internal data acquisition system and are reported to the user through a
vacuum fluorescence display or several output ports.
MEASUREMENT PRINCIPLE
C
HEMILUMINESCENCE
The analyzer measures the amount of NO present in a gas by detecting the
chemiluminescence which occurs when nitrogen oxide (NO) is exposed to ozone (O
reaction is a two-step process:
•
In the first step, one molecule of NO and one molecule of O
react to produce one molecule of oxygen (O
(NO
). Some of the NO
2
the collision and exist in an excited state, where one of the electrons of the NO
molecule resides in a higher energy state than normal (denoted by an asterisk in the
following equation).
176
Teledyne API T200 NO/NO
) and nitrogen dioxide (NO
2
and NO.
X
concentration.
X
C
REATION IN THE
molecules created by this reaction retain excess energy from
2
NO
O
+
3
/NO
Analyzer with NumaView™ Software
2
x
) in a sample gas drawn through the instrument.
2
), initiating a chemical reaction that gives off light
3
in the sample gas to NO which, along with
2
. NO
is calculated as the difference
X
2
are supplied and stores these
2
R
EACTION
3
) and one molecule of nitrogen dioxide
2
*
NO
O
→
+
2
2
, the sum of
X
C
ELL
)
This
3
.
collide and chemically
2
Equation 6-1
083730200A DCN7962
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