The oxygen analyzer in your N2 generator monitors nitrogen purity in real time. Keeping it properly configured is critical for accurate purity readings and reliable system performance. We recommend verifying analyzer accuracy at least once a year — and any time purity readings appear inconsistent with expected performance, particularly following a preventive maintenance event.
Understanding Your Analyzer Hardware
Older N2 generators route the sample line directly to the O2 sensor. Newer units include an upgraded analyzer assembly with an integrated regulator and flow control valve, which stabilizes gas flow across the sensor and produces more consistent readings.
The calibration procedure below applies to both configurations. If you are unsure which assembly your unit has, contact our support team before proceeding.
Calibration Set Points — Current Standard
Based on updated engineering guidance, PSA nitrogen generators should be calibrated using factory-defined set points. These values have been validated to produce accurate purity readings without requiring calibration gas to derive raw sensor values.
⚠ Important: Calibration gas should be used for verification only — not to set calibration values. See the Verifying Analyzer Accuracy section below.
For PPM units, enter the following values in the calibration menu:
| Field | Value |
|---|---|
| Low Raw | 819 |
| High Raw | 4095 |
| Low Cal | 0 |
| High Cal | 1000 |
Accessing the Calibration Menu
- Turn the generator to the OFF position.
- Close the ball valve on the sample line at the nitrogen storage tank.
- Disconnect the sample line from the sample port on the outside of the electrical cabinet.
- On the PLC display, press Menu.
- Enter password 6557 and press the Return key (bottom-right button).
- Select Sensor Setup / Calibration.
- Select O2 PPM/% Calibration.
Entering Calibration Values
PPM units
Enter the factory set points from the table above:
- Low Raw = 819
- High Raw = 4095
- Low Cal = 0
- High Cal = 1000
% (Percentage) O₂ units
For units configured to display in percent rather than PPM, calibration gas values are still required:
- Enter the concentration value from your test gas canister (typically 1%) into the "0–2% O₂ Calibration Gas" field.
- Enter 20.9% into the "20–22% O₂ Calibration Gas" field.
Need test gas? Contact us at support@southteksystems911.zendesk.com or (910) 415-1880 to request a quote.
Completing the Procedure
Once calibration values have been entered:
- Exit the calibration menu and return to the main screen.
- Reconnect the sample line to the sample port on the electrical cabinet.
- Open the ball valve at the nitrogen storage tank to resume normal N2 flow to the analyzer.
- Restart the generator and allow the system to fully cycle before evaluating purity output.
Verifying Analyzer Accuracy
After setting calibration values, calibration gas can be used to confirm the analyzer is reading correctly.
- Connect the sample line to a canister of known test gas.
- Allow gas to flow for at least 5 minutes before reading the display.
- Confirm the displayed value reasonably matches the concentration printed on the canister.
ℹ Note on calibration gas range: The analyzer is calibrated across a 0–1000 PPM span using factory set points. If you are using 700 PPM verification gas and observe a slight variance from the canister value, this is expected behavior. A significant or growing discrepancy warrants a review of your set point entries or a call to our support team.
Purity Issues After Preventive Maintenance
If your system was producing acceptable purity prior to a PM event and purity has since dropped, analyzer calibration is one of the first things to verify. Common post-PM scenarios that can affect purity readings include:
- Calibration values altered or reset during the PM
- Pilot regulator disturbed during reassembly — confirm pilot pressure is in the 90–100 PSI range at the controller
- New CMS material added to the beds — beds may require additional cycle time to equilibrate after a top-off or full media replacement
- Sample line reconnected improperly, allowing ambient air to influence sensor readings
If recalibrating the analyzer does not restore expected purity levels, contact our support team to schedule a remote diagnostic session or field visit.
Contact South-Tek Systems
📞 (910) 415-1880
📧 support@southteksystems911.zendesk.com