Analytical Industries GPR-1800 IS ATEX Trace PPM Oxygen Transmitter - Manual (Page 26)

Advanced Instruments, Inc
26
Span Gas vs. Air Calibration
The analyzer can be calibrated by using ambient air (20.9% O
2
) or a certified span gas. The only advantage
of using a certified span gas for calibration is the fast recovery time to low PPM level after calibration. For
example, if the analyzer is calibrated by using 8 PPM span gas, the analyzer will recover to within 0.1 PPM
of the original reading within five minutes. On the other hand, if the analyzer is calibrated with ambient air, it
may take 1-2 hours for the reading to get below 0.5 PPM
Zero Calibration Procedure
Zero calibration should be carried out after the span calibration has been performed. Normally, zero
calibrations are performed when a new sensor is installed or changes are made in the sample system
connections.
Before performing a ZERO calibration, it is highly recommended to perform a factory default zero. This will
eliminate previous zero offset adjustment that might have been made. With factory default setting, if the zero
offset does not exceed 50% of the lowest range, this indicates that the integrity of the sensor, the analyzer
sample system and the sample line bringing in the sample gas is maintained.
Access the MAIN MENU by pressing the MENU key.
Advance the reverse shade cursor using the ARROW keys to highlight CALIBRATION.
Press the ENTER key to select the highlighted menu option.
The following displays appear:
MAIN MENU
AUTO SAMPLE
MANUAL SAMPLE
CALIBRATION
CONFIG ALARMS
BYPASS ALARMS
>>>
CALIBRATION
SPAN CALIBRATE
ZERO CALIBRATE
DEFAULT SPAN
DEFAULT ZERO
OUTPUT SPAN
OUTPUT ZERO
Advance the reverse shade cursor using the ARROW keys to highlight ZERO CALIBRATE.
Press the ENTER key to select the highlighted menu option.
The following displays appear:
ZERO
CALIBRATION
ENTER TO CALIBRATE
MENUE TO ABORT
Press the ENTER key to calibrate or MENU key to abort and return to SAMPLING mode.
Allow approximately 60 seconds for the calibration process while the microprocessor determines whether
the signal output or reading has stabilized within 50% of the full scale low range. If the offset is less than
50% of the lowest range, by pressing ENTER, message PASSED CALIBRATION will appear and return to
the Sample mode. On the other hand, if the offset is above 50%, pressing ENTER, message FAILED