Thermo Scientific 42iQLS, Instruction Manual

Page: 172 / 318

Calibration
Equipment Required
4-6 42iQLS Instruction Manual Thermo Scientific
3. Plot the analyzer NO response (in ppm) versus the nominal diluted
NO concentration and determine the slope, S
NOM
.
4. Calculate the [NO] concentration of the working standard, [NO]
STD
,
from:
S
x ] [NO = ] [NO
NOM
NOM STD
5. If the nominal NO concentration of the working standard is unknown,
generate several NO concentrations to give on-scale NO responses.
6. Measure and record F
NO
and F
T
for each NO concentration generated.
7. Plot the analyzer NO response versus F
NO
/F
T
and determine the slope
which gives [NO]
STD
directly. The analyzer NO
x
responses to the
generated NO concentrations reflect any NO
2
impurity in the NO
working standard.
8. Plot the difference between the analyzer NO
x
and NO responses versus
F
NO
/F
T
. The slope of this plot is [NO
2
]
IMP
.
A source of zero air free of contaminants should be used as described earlier
in this chapter. Contaminants can cause a detectable response on the
instrument and may also react with the NO, O
3
, or NO
2
during the gas
phase titration.
Use the following definitions for the remainder of this chapter.
P
R
= Dynamic parameter specification to ensure complete reaction of the
available O
3
, ppm-min
[NO]
RC
= NO concentration in the reaction chamber, ppm
t
R
= residence time of the reactant gases in the reaction chamber, min
[NO]
STD
= Concentration of the undiluted NO standard, ppm
F
NO
= NO flow rate, sccm
F
O
= O
3
generator air flow rate, sccm
V
RC
= Volume of the reaction chamber, cc
F
T
= Analyzer demand plus 10 to 50% excess
Zero Air
Dynamic Parameter
Specifications for
Gas Titrator