Thermo Scientific 42i Instruction Manual page 138

Calibration
Equipment Required
Dynamic Parameter
Specifications for
Gas Titrator
Determining GPT System
Flow Conditions
4-6 Model 42i Instruction Manual
8. Plot the difference between the analyzer NO
F /F
NO T
Zero Air
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
phase titration.
Use the following definitions for the remainder of this chapter.
P =
R
[NO] =
RC
t =
R
[NO] =
STD
F =
NO
F =
O
V =
RC
F =
T
The O generator (ozonator) airflow rate and the NO flow rate must be
3
adjusted such that the following relationships hold:
Use the following procedure to determine the flow conditions to be used in
the GPT system.
1. Determine FT, the total flow required at the output manifold, which
should be equal to the analyzer demand plus 10 to 50 percent excess.
. The slope of this plot is [NO
Dynamic parameter specification to ensure complete reaction of the
available O , ppm-min
3
NO concentration in the reaction chamber, ppm
residence time of the reactant gases in the reaction chamber, min
Concentration of the undiluted NO standard, ppm
NO flow rate, sccm
O generator air flow rate, sccm
3
Volume of the reaction chamber, cc
Analyzer demand plus 10 to 50% excess
= [NO t x
]
P
R R
RC
[NO ] = [NO ]
RC STD
V
RC
=
t
R
+
F
O
and NO responses versus
x
] .
2 IMP
, or NO
3 2

2.75 ppm - min
F
NO
( + )
F F
O NO
< 2 min
F
NO
during the gas
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