Calibration
Multi-Point Calibration
Thermo Fisher Scientific
Model 43i Trace Level-Enhanced Instruction Manual
4-5
Regulations typically require zero/span calibration when the instrument is
newly installed, moved, repaired, interrupted for more than a few days, or
when span or zero shift by more than 15%.
All gas must be supplied to the instrument at atmospheric pressure. It may
be necessary to employ an atmospheric bypass plumbing arrangement to
accomplish this. Refer to
Figure 2–4
in the “Installation” chapter for an
example of an atmospheric bypass plumbing arrangement.
If a filter is used, all gas must enter the instrument through the filter.
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.
▲
Use the following procedure to perform a zero/span calibration.
1.
If the instrument is equipped with the optional zero/span and sample
valves, connect the zero and span gas to the rear panel bulkheads
labeled ZERO and SPAN, otherwise connect a source of vented zero air
to the SAMPLE bulkhead.
Note
Do not use nitrogen for zero air.
▲
is used to activate the zero and span valves. The lower left-hand
corner of the Run screen indicates which mode is active: ZERO,
SPAN, or SAMPLE.
2.
To ensure that the zero air is being measured at atmospheric pressure,
check that the zero air flow reported by the analyzer is approximately
Multi-Point
Calibration
