Analytical Industries GPR-2000 ATEX Portable Oxygen Analyzer - Manual (Page 19)

Advanced Instruments Inc.
19
7. Compute the adjustment value as described in Appendix B or consult the factory. The true adjustment value must be
determined empirically by trial and error. Adjust the initial adjustment value for additional percent errors.
090.0
OUTPUT ZERO OFFSET
PRESS UP OR DOWN
TO CHANGE VALUE
ENTER TO SAVE
MENU TO RETURN
8. Press the ENTER key to advance the underline cursor right or press the MENU key to advance the underline cursor left to
reach to the desired digit of the OUTPUT ZERO OFFSET value.
9. Press the ARROW keys to enter the OUTPUT ZERO OFFSET value.
10. Repeat until the complete OUTPUT ZERO OFFSET value has been entered.
11. Save the adjustment value by pressing the ENTER key or abort by pressing the MENU key.
12. The system returns to the SAMPLING mode.
Span Calibration
Span Calibration involves adjusting the transmitter electronics to the sensor’s signal output at a given oxygen standard.
Maximum drift from calibration temperature is approximately 0.11% of reading per °C. The frequency of calibration varies with
the application conditions, the degree of accuracy required by the application and the quality requirements of the user.
However, the interval between span calibrations should not exceed three (3) months.
Note: Regardless of the oxygen concentration of the standard used, the span calibration process takes approximately 10
minutes, however, the time required to bring the analyzer back on-line can vary depending on a combination of factors and
assume exposure to a zero/purge/sample gas** with an oxygen content below the stated thresholds immediately after span
calibration:
* Refer to analyzer specifications for comparable data on the Pico-Ion UHP and MS oxygen sensors.
Recommendations General:
¾ The interval between span calibrations should not exceed three (3) months.
¾ Initiate the DEFAULT ZERO and DEFAULT SPAN procedures before performing either a ZERO or SPAN CALIBRATION.
¾ Caution: Prematurely initiating the SPAN CALIBRATION function before the analyzer reading has stabilized can result in
erroneous readings. This is especially true when installing a new sensor that must adjust to the difference in oxygen
concentrations. It should take about 2 minutes for the sensor to equilibrate in ambient air from storage packaging.
¾ Always calibrate at the same temperature and pressure of the sample gas stream.
¾ For 'optimum calibration accuracy' calibrate with a span gas approximating 80% of the full scale range one or a higher
range than the full scale range of interest (normal use) to achieve the effect of “narrowing the error” by moving downscale
as illustrated by Graph A in the Accuracy & Calibration section.