Thermo 42i - Page 133

Calibration
Calibration
Thermo Electron Corporation Model 42i Low Source Instruction Manual 4-5
The O
3
generator (ozonator) airflow rate and the NO flow rate must be
adjusted such that the following relationships hold:
Determining GPT System Flow
Conditions
Use the following procedure to determine the flow conditions to be used in
the GPT system.
1. Determine F
T
, the total flow required at the output manifold, which
should be equal to the analyzer demand plus 10 to 50 percent excess.
2. Establish [NO]
OUT
as the highest NO concentration that will be
required at the output manifold. [NO]
OUT
should be about equal to
90% of the upper range limit (URL) of the NO
2
concentration range to
be covered.
3. Determine F
NO
as:
4. Select a convenient or available reaction chamber volume. Initially a
trial volume may be selected in the range of 200 to 500 cc.
5. Compute F
O
as:
min-ppm2.75
t
x
]
[NO=
P
R
RC
R
t
)
F
+
F
(
F
]
[NO=
]
[NO
NOO
NO
STDRC
min2<
F
+
F
V
=
t
NOO
RC
R
]
[NO
F
x
]
[NO
=
F
STD
T
OUT
NO
F
-
2.75
V
x
F
x
]
[NO
=
F
NO
RC
NO
STD
O