Thermo 42i, Instruction Manual

Page: 129 / 314

Thermo Electron Corporation Model 42
i
Low Source Instruction Manual 4-1
Chapter 4
Calibration
This chapter describes procedures for performing a calibration of the Model
42
i Low Source. The information described here should be adequate to
perform the calibration. However, if greater detail is desired, due to
particular application requirements, the factory should be consulted.
Equipment Required
A zero air source, free of contaminants such as NO, NO
2
, and O
3
is
required for dilution, calibration, and gas phase titration. This can be a
cylinder of zero gas, a scrubbed, compressed air source, or room air,
depending on the concentration of NO
x
to be measured and the level of
NO
x
in the ambient area.
Pre-Calibration
Use the following procedure before calibrating the Model 42 i Low Source.
For detailed information about the menu parameters and the icons used in
these procedures, see the “Operation” chapter.
Note
The calibration and calibration check duration times should be long
enough to account for the transition (purge) process when switching from
sample to zero and from zero to span. This transition time is the time
required to purge the existing air.
Depending on the plumbing configuration and the instrument, data from
approximately the first minute of a zero calibration or check should be
disregarded because of residual sample air. Also, data from approximately
the first minute of a span calibration or check should be disregarded because
the span is mixing with the residual zero air.
1. Allow the instrument to warm up and stabilize.
2. Be sure the ozonator is ON. If the ozonator is not ON:
a. Press to display the Main Menu, then choose Instrument
Controls > Ozonator .
b. Press to toggle the ozonator ON.
c. Press to return to the Run screen.