Rosemount 890, Instruction Manual

Page: 58 / 96

I
NITIAL
S
TARTUP AND
C
ALIBRATION
Rosemount Analytical 748460-A January 2000
3-28
3.18 INTERFERENCE BALANCE
SO
2
Measurement
The Model 890 analyzer may be calibrated for a dynamic interferent gas rejection ratio
of up to 1000:1 for samples containing single, binary or multiple interferents. This
calibration is initially done at the factory, and generally is a one-time adjustment.
Re-adjustment in the field should be done only if: (1) The optical filters are replaced or
(2) the sample stream composition has changed drastically from the original
composition.
The balance adjustment is an electronic adjustment. If the interference setting is
changed, the balance potentiometer can be used to balance the system. This is a fine
adjustment.
If more adjustment than the potentiometer can provide is necessary, the iris can be
used to balance the system to zero. See Section 5.2.
Cl
2
Measurement
Use of the Model 890 for Cl2 measurement require a stable concentration of
interferent gas for the compensation factor to remain accurate. Otherwise, displayed
readings are not dependable.
Adjustment is An electronic adjustment, which can be accessed through the
INTERFERENCE CAL function in the MODE menu structure (see Figure 3-4).