Instruction manual
SM425 INSTRUCTION MANUAL 9.0 CALIBRATION
Select “Zero gas conc.” in the Calibration setup display screen. The numeric-data entry display
then appears. Enter the desired oxygen concentration for the zero-point calibration. (The zero-
gas set ranges from 0.3 to 100 % O
2
.)
Enter 00098 for an oxygen concentration of 0.98 vol% O
2
.
9.2.1.4 Setting Span-gas Concentration Value
To enter the oxygen concentration of the span-gas:
Select “Span gas conc.” in the Calibration setup display screen. Enter the desired span-gas
oxygen concentration using the numeric-data entry display. If instrument air is used as the span
gas, enter 21 % O
2
. (The span-gas set ranges from 4.5 to 100 % O
2
.)
Enter 02100 for an oxygen concentration of 21 vol% O
2
.
Instrument air is here defined as dry air with a dew-point temperature of no higher than -20°C. If the dew-
point temperature is higher than -20°C, use a hand-held oxygen analyzer to measure the actual oxygen
concentration.
If using the ZO21S Standard Gas Unit and atmospheric air as the span gas, determine the actual oxygen
concentration with a hand-held oxygen analyzer.
- When instrument air is used for the span calibration, remove the moisture from the instrument air to a
dew-point temperature of -20°C and remove any oil and particulate from that air.
- Measurement accuracy is adversely affected if the air is not clean and sufficiently dehumidified.
9.2.1.5 Setting Calibration Timing
Calibration timing consists of five parameters: Hold time, Csl time, Interval, Start date, and Start time.
These parameters are entered using the “Calibration Timing Display” which appears when “Timing” is
selected on the “Calibration setup” display screen. Select the appropriate parameter and enter the
desired value.
Figure 9-6 “Calibration Timing” Display
Hold time is the stabilization period following a calibration during which process gas diffuses back into the
sensor. Normal measurements are resumed after completion of this stabilization period. See Figure 9-7.
During this period, the analog output is held to the value obtained just prior to calibration. For more
148 42500001 REV A