Teledyne T200, Operation Manual, Page: 290 / 425

Principles of Operation Teledyne API
– T200 NO/NO2/NOx Analyzer Operation Manual
288
SAMPL E
PRESSURE
SENSOR
VACUUM
PRESSURE
SENSOR
O
3
FLOW
SENSOR
FLOW PRESSURE
SENSOR PCA
INSTRUMENT CHASSIS
PMT
NO/NO
X
VALVE
AUTOZERO
VALVE
O
3
Destruct
O
3
GENERATOR
O
3
Cleanser
EX HAUST
GAS OUTLET
SAMPLE
GAS INLET
NO
2
Converter
Orifice Dia.
0.004"
Orifice Dia.
0.010"
PUMP
NO
X
Ex
h
a
u
s
t
Sc
ru
b
b
e
r
OZONE DRYER
F
ilt
er
Orifice Dia.
0.004"
EXH
AU
ST
M
AN
IF
O
LD
Orifice Dia.
0.010"
COM
NC
NO
NC
COM
NO
Figure 13-4: Pneumatic Flow During the Auto Zero Cycle
13.1.5. MEASUREMENT INTERFERENCES
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.
13.1.5.1. DIRECT INTERFERENCE
Some gases can directly alter the amount of light detected by the PMT due to
chemiluminescence in the reaction cell. This can either be a gas that undergoes
chemiluminescence by reacting with O
3
in the reaction cell or a gas that reacts with
other compounds and produces excess NO upstream of the reaction cell.
13.1.5.2. THIRD BODY QUENCHING
As described by Equation 13-3, other molecules in the reaction cell can collide with the
excited NO
2
*
, causing the excited NO
2
*
to return to its ground state without releasing a
photon of light. This is known as third party quenching.
06858E DCN7057