Thermo 42i, Instruction Manual

Page: 49 / 314

Operation
Calibration Factors Menu
Thermo Electron Corporation Model 42
i
Low Source Instruction Manual 3-21
NO, NO
2
, and NO
x
Coefficients
The NO, NO
2
, and NO
x
span coefficients are usually calculated by the
instrument processor during calibration. The span coefficients are used to
correct the NO, NO
2
, and NO
x
readings. The NO and NO
x
span
coefficients normally have values near 1.000. The NO
2
span coefficient
normally has a value between 0.95 and 1.050.
The NO, NO
2
, and NO
x
Coefficient screens allow the NO, NO
2
, and
NO
x
span coefficients to be manually changed while sampling span gas of
known concentration. The NO, NO
2
, and NO
x
coefficient screens operate
the same way. Therefore, the following description of the NO coefficient
screen applies to the NO
2
and NO
x
coefficient screens as well.
The display shows the current NO concentration reading. The next line of
the display shows the NO span coefficient that is stored in memory and is
being used to correct the NO concentration. Notice that as the span
coefficient value is changed, the current NO concentration reading on the
above line also changes. However, no real changes are made to the value
stored in memory until
is pressed. Only proposed changes, as
indicated by a question mark prompt, are displayed until is pressed.
In dual or auto range mode, “High” or “Low” is displayed to indicate the
calibration of the high or low coefficient. The example below shows the
coefficient screen in single mode.
Note The concentration value will show ERROR if the measured
concentration is not a valid span value (either higher than the selected
range, or 0 or lower).
• In the Main Menu, choose Calibration Factors > NO, NO
2
or NO
x
Coef .
• Use and to increment or decrement the coefficient value.
• Press to save the new coefficient.
NO COEFFICIENT:
NO: 51.4
SET COEF TO: 1.000 ?
©ª
INC/DEC
ƒ
SAVE VALUE
RANGE AVG DIAGS ALARM