3
S
TARTUP AND
C
ALIBRATION
748213-P Rosemount Analytical June 1997
3-1
Model 755R Oxygen Analyzer
3.1 OVERVIEW
Preparatory to startup and calibration, a familiarization with Figure 3-1 is
recommended. This figure gives locations and summarized descriptions of operating
adjustments of the Model 755R Oxygen Analyzer.
3.2 OPERATING RANGE SELECTION
The Model 755R is designed to operate on a single, field-selectable range. A new
range may be selected any time the analyzer application changes or any time
calibration may require a range change.
To select the operating range, reposition the jumper shown in Figure 3-1 to the
desired location. Each position is labeled as to its fullscale range. Only the analog
output (voltage and optional current) is affected by range selection. The digital display
always reads 100% oxygen.
3.3 STARTUP PROCEDURE
Inject a suitable on-scale gas (not actual sample) through the analyzer. Turn power
ON. If digital display gives overrange indication, the probable cause is the suspension
in the detector is hung up. To correct this condition, turn power OFF, tap detector
compartment with fingers, wait 30 seconds, turn power ON.
When on-scale reading is obtained, allow analyzer to warm-up for a minimum of one
hour with gas flowing. This warm-up is necessary because a reliable calibration is
obtainable only after the analyzer reaches temperature stability. Moreover, the
resultant elevated temperature will ensure against condensation within, and possible
damage to the detector assembly. After warm-up, the digital display or recorder
should give stable, drift-free readout. If so, proceed to Section 3.3. Otherwise, refer
to Section 7, Service and Maintenance.
3.4 CALIBRATION
Calibration consists of establishing a zero calibration point and a span calibration point
(see Table 3-1). Zero and span calibration should be performed on the range that will
be used during sample analysis. In some applications, however, it may be desirable
