Analytical Industries GPR-3100 Series Oxygen Purity Analyzer - Manual (Page 28)

Advanced Instruments Inc.
5 Operation
GPR-3100 Rev 2/05 21
span calibration again for up to 3 months under “normal” application conditions as described in the
published specifications.
In standard configuration, the GPR-3100 can be calibrated by exposing the sensor to the readily available
cost effective and reliable 20.9% (209,000 ppm) oxygen concentration of ordinary atmospheric air or a
certified span gas with an oxygen concentration of 80-100% of full scale range balance nitrogen. For
example, for a 0-25% range, the span gas should be a certified grade between 19-23% oxygen
preferably approximately 20.9% oxygen.
Accuracy due to manufacturer tolerances may result in a slight difference between the LCD display and
the analog output of the 4-20mA integrated circuit. However, the difference is less than 0.25% of range
and falls well below the specified accuracy of the analyzer.
Factory Default Span
The software will set the SPAN adjustment based on the average oxygen reading (actually the sensor’s
signal output) at a specified oxygen concentration. For example, when a span gas is introduced, the
micro-processor will display an oxygen reading within +50% of the span gas value. This feature allows
the user to test the sensor’s signal output without removing it from the sensor housing.
Manual Span
The user must ascertain that the oxygen reading (actually the sensor’s signal output) has reached a
stable value within the limits entered below before entering the span adjustment. Failure to do so will
result in an error. Entering the span value – follow the menu layout in Appendix A.
Procedure:
1. Recommended for flow through configurations, refer to Appendix A for a description of this features
and operational instructions.
2. Select the RANGE dictated by the accuracy of the analysis required, see Calibration – General
Guideline above
3. Advance the cursor (*) on the MAIN MENU to SAMPLE and press ENTER to accept the selection.
4. From the above SAMPLE menu advance the cursor (*) to MANUAL RANGING and press ENTER.
5. Advance the cursor (*) on the MAN RANGE menu the RANGE dictated by the span gas and press
ENTER to select.
6. Return to the MAIN MENU and display the oxygen concentration of the span gas.
7. Assure there are no restrictions in the span gas line.
8. Regulate the pressue and control the flow rate as described above, 5-30 psig and 2 SCFH flow rate.
9. Start the flow of span gas, before disconnecting the sample gas line, to purge the air trapped in the
span gas line – allow the span gas to flow for about 2 minutes.
10. Disconnect the sample gas line and replace it with the purged span gas line.
11. Wait 10-15 minutes to ensure the reading is stable (a premature adjustment will cause drift).
12. Allow the oxygen reading to stabilize. The analyzer would typically stabilize in 5-15 minutes.
13. Refer to Appendix A and advance the cursor (*) on the MAIN MENU to SPAN and press ENTER to
accept the selection.
14. From the SPAN menu advance the cursor (*) to Calibrate and press ENTER to select.
15. Follow the menus in Appendix A to enter and accept the span value.