Analytical Industries GPR-1600 MS Series PPB Oxygen Analyzer - Manual (Page 34)

Advanced Instruments Inc.
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routine subsequent SPAN CALIBRATION.
¾ If a ZERO CALIBRATION adjustment has NOT been made as described above, perform the DEFAULT ZERO and DEFAULT
SPAN functions when troubleshooting an analyzer and before 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 For 'optimum SPAN CALIBRATION accuracy' use a span gas approximating 80% of the full scale range higher range than
the 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.
¾ SPAN CALIBRATION with a span gas approximating 5-10% of the full scale range near the expected oxygen concentration
of the sample gas is acceptable but less accurate than ‘optimum SPAN CALIBRATION accuracy’ method recommended – the
method usually depends on the gas available.
¾ SPAN CALIBRATION at the same 5-10% of the full scale range for measurements at the higher end of the range (example:
calibrating an Oxygen Purity Analyzer in air at 20.9% oxygen with the intention of measuring oxygen levels of 50-100%)
results in the effect of “expanding the error” by moving upscale as illustrated by Graph A and Example 1 in the Accuracy &
Calibration section above and is not recommended. Of course the user can always elect at his discretion to accept an
accuracy error of +2-3% of full scale range if no other span gas is available.
Recommendations Air Calibration:
¾ Do not calibrate an analyzer employing the Pico-Ion UHP or MS sensor, or, an oxygen purity sensor with air.
Procedure Span Calibration with Span Gas:
This procedure assumes a span gas under positive pressure and is recommended for a analyzer without an optional sampling
pump, which if installed downstream of the sensor should be placed in the OFF position and disconnected so the vent is not
restricted during calibration.
For calibration purposes, use of the AUTO SAMPLE mode is recommended. However, the user can select the full scale MANUAL
SAMPLE RANGE for calibration as dictated by the accuracy of the analysis required – for example, a span gas with an 80 ppm
oxygen concentration with the balance nitrogen would dictate the use of the 0-100 ppm full scale range for calibration and a 0-
10 ppm measuring range. Select as described in the Range Selection section above.
1. Assembly the required components described in the Installing Span Gas section above.
2. Access the MAIN MENU by pressing the MENU key.
3. The following display appears:
MAIN MENU
AUTO SAMPLE
MANUAL SAMPLE
CALIBRATION
CONFIG ALARMS
BYPASS ALARMS
4. Advance the reverse shade cursor using the ARROW keys to highlight CALIBRATION
5. Press the ENTER key to select the highlighted menu option.
6. The following display appears: