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| Technical Note No. 102 |
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| ALARMLOG Oxygen Level Monitor - Sensor Calibration Compensation | ||||
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The oxygen sensor user by the ALARMLOG Oxygen Level monitor, model UL2-01-S1, uses an
electrochemical galvonic sensor, which generates a d.c. output voltage directly proportional
to atmospheric oxygen level. The calibration of this sensor is 1.275 mV +/- 0.025 mV /
%02.
The ALARMLOG itself is always calibrated assuming a nominal sensor output of 1.275 mV / %02. To compensate for differences in sensor sensitivity, a correction may be applied via the ALARMLOG keypad to set the measured oxygen level to the correct value derived from a reference gas level or other measurement using a reference instrument. Once set, the calibration correction is applied to all subsequent measurements, until changed. Calibration Compensation Procedure As described above, the ALARMLOG is calibrated assuming an oxygen sensor with nominal calibration. Corrections to compensate for variations in sensor sensitivity can be applied directly from the ALARMLOG keypad by adjusting the displayed value to the correct value for a known oxygen concentration derived either from a reference gas or from measurements made using a reference instrument. As the output of the oxygen sensor is inherently linear and is zero for 0 %O2, only a single correction need be made at any known oxygen level. It is recommended, however, that calibration corrections be undertaken at an oxygen level near that expected in normal operation. |
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| Step | Procedure | |||
| 1 | Enable oxygen level monitor calibration using the Enable Oxygen Level Monitor Calibration function of the ALARMLOG for Windows 32 program or the SCANLOG for Windows 32 program. | |||
| 2 | On the ALARMLOG, press and hold the Set keypad key. | |||
| 3 | Immediately [within 1 second] press and hold both the Up and Down keys. | |||
| 4 | After approximately 2 seconds, the display will indicate a minus sign at the left, of the displayed oxygen reading, indicating that calibration correction has been enabled. Now release the Set, Up and Down keys. | |||
| 5 |
Using either the Up or Down key, increase or decrease the displayed
oxygen level to match the true level.
Each button press will change the measured value by approximately 0.08 %O2 at 20 % O2. If a button is held the value will scroll. The maximum correction which may be applied is approximately +/- 2.50 %O2 at 20 %O2. |
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| 6 | When the correct reading has been obtained, press the Set key again to restore normal operation. | |||
| 7 | From the PC program, save the new calibration date to the ALARMLOG, if required, and select Reset to restore the ALARMLOG to its previous operating state. | |||
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Derived from Document 0422/UA/00 Issue 1 Last modified: 23 October 1999 |
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