Measurement Interferences - Teledyne T200 Operation Manual

Principles of Operation
SAMPLE
GAS INLET
EX HA UST
GAS OUTLET
PUMP

13.1.5. MEASUREMENT INTERFERENCES

13.1.5.1. DIRECT INTERFERENCE
13.1.5.2. THIRD BODY QUENCHING
288
Teledyne API – T200 NO/NO2/NOx Analyzer Operation Manual
Converter
Orifice Dia.
0.010"
Orifice Dia.
0.004"
OZONE DRYER
Figure 13-4: Pneumatic Flow During the Auto Zero Cycle
It should be noted that the chemiluminescence method is subject to interferences from a
number of sources. The T200 has been successfully tested for its ability to reject
interference from most of these sources. Table 13-1 list the most common types of
interferents that could affect the performance of your T200.
Some gases can directly alter the amount of light detected by the PMT due to
chemiluminescence in the reaction cell.
chemiluminescence by reacting with O
other compounds and produces excess NO upstream of the reaction cell.
As described by Equation 13-3, other molecules in the reaction cell can collide with the
*
excited NO , causing the excited NO
2
photon of light. This is known as third party quenching.
NO/NO
X
VALVE
COM NO
NC
NO
2
AUTOZERO
VALVE
NO
NC
O
3
COM
Cleanser
Orifice Dia. Orifice Dia.
0.010" 0.004"
PMT
This can either be a gas that undergoes
in the reaction cell or a gas that reacts with
3
*
to return to its ground state without releasing a
2
FLOW PRESSURE
SENSOR PCA
SAMPL E VACUUM
PRESS URE PRESS URE
SENSO R SENSO R
O FLOW
3
SENSO R
O
3
GENERATOR
O
3
Destruct
INSTRUMENT CHASSIS
06858E DCN7057