Calibration Setting
These are common settings applicable for all calibration sequences defined under the station/site/group. These settings define data to decide whether a calibration is successful or not as explained below
To add/modify calibration settings:
1. Click on Calibration then click on Calibration Setting
2. Calibration Settings page appears on the right hand side of the screen as shown below:
3. Select the group from 'Select Group' drop down box.
Limits – Set factor low and high limit range [typical 0.8 to 1.2]
- Span Drift [% of REF.] - Set the allowable percent Span variation (drift) [typical 4%-10%]. Drift = Measured span – Expected span.
- Zero Drift [% of Range] - Set the allowable percent Zero variation (drift) [typical 4%-10% of Range]. Drift = Measured zero – Expected zero.
- Data Correction – Yes/No this flag indicates if data correction is to be done after successful calibration. If yes, each data value read after calibration is corrected using the formula –
Y = Factor * X – Zero
Where, factor and zero as calculated on calibration mapping screen
X – read value of analyzer
- Calibrator section contains selection of calibrator device and reset string. Here it assigns calibrator device for the selected group. Reset string is used to reset the calibrator.
5. Click Save/Modify.
Validation rules for calibration:
For valid calibration following rules should be satisfied –
- Calculated Factor should be within the defined limits.
- Zero Drift or field ‘Zero’ should be within the defined variation
E.g. If zero drift is = 5% and range/reference = 500, so zero drift allowable range should be -25 to 25. This means calculated field ‘Zero’ should be between -25 and 25
- Span Drift should be within the defined variation. This is Measured Span – Expected Span
E.g. If span drift = 4% and range/reference = 500, so span drift allowable range should be -20 to 20.
If any of the above rules are not satisfied, then the calibration is not valid.
Error handling:
- If any error occurred during calibration, then abort the calibration and reset calibrator. Store the status.
- Don't allow to change the cal. sequence during calibration in progress.
- If calibration in progress for one analyzer, don't allow to start calibration for any other analyzer on same site.