ATI
Model F12/D Gas Transmitter
Part 4
– Operation
43
O&M Manual (Rev-H)
Sensor Calibration History
A calibration record is written into the sensor memory each time a zero or span calibration is performed.
Enough memory is reserved for 63 zero calibrations and 63 span calibrations. Zero and span calibration
records are accessed on the Sensor Calibration History page.
Figure 52. Sensor Calibration History Menus
Zero calibration records are composed of an index field (record no/total records), date, concentration
reading, and gas name. The reading is recorded just before applying the correction, and can be thought of
as “drift” from the previous zero calibration. Upon entry, the index number is set to the most recent
calibration and may be scrolled down to view earlier calibration records.
Span calibration records are composed of an index field, date, and the relative sensitivity of the sensor.
Like the zero records, the index number is set to index the most recent calibration and may be scrolled
down to view earlier calibration records. Span calibrations record the deviation from the reference
sensitivity and display it in units of percent. Sensitivity is a measure of the sensor output for a given
exposure to gas. More specifically, it is defined as the ratio of the signal output to the gas concentration
and is often measured in µA/PPM. During manufacture, the sensitivity of the sensor is recorded and used
as a reference. A value of 100% signifies that the sensitivity has not changed from the reference e.g., the
sensor calibration is the same at it was when the sensor was calibrated at the factory. Lower values indicate
a decreased sensitivity and, although not typical, higher values indicate increased sensitivity. When the
sensitivity drops to 10% it is time to replace the sensor.
Zero History
►1/1 09/12/14
0.0 PPM
H2S
…History>Zero
Calibration
Zero ►History
Span
Temp= 21.1°C
…Setup >Sensor>Calibration
Cal History
►Zero
Span
…Calibration>History
Span History
►1/1 09/12/14
100 %sens
H2S
…History>Span
Cal History
Zero
►Span
…Calibration>History
