We recommend you zero and span calibrate:
- Upon initial installation
- After relocation
- After any repairs or service that might affect its calibration
- When there is prolonged interruption in operation
- At a nominated routine frequency.
The frequency of routine calibration is a trade-off between desired accuracy and economic factors. More frequent calibration gives greater confidence in the accuracy of the measurements, but it also results in higher cost in terms of materials and labor. For simplicity, we recommend one of two calibration regimes.
- Indicative monitoring. An initial field calibration upon deployment followed by at least quarterly gas module calibrations with weekly data inspections to identify early evidence of sensor drift.
- Compliance monitoring. An initial field calibration upon commissioning followed by at least monthly gas module calibrations and daily data inspections. However, National, State or Federal compliance monitoring regulations may apply to the project and these should be consulted to ensure your intended calibration schedule fully complies.
Routine frequency also depends on site conditions and data quality objectives. Very dirty measurement sites with high pollution levels require more frequent calibrations, as do projects where the data quality (accuracy) requirements are high.
It’s difficult to provide strict recommendations for calibration frequency but the following points give an indication:
- For very dirty sites requiring high measurement accuracy, calibration frequency could be once per week.
- For moderate dirty sites or sites requiring medium measurement accuracy, calibration frequency could be once per month.
- For cleaner or background sites requiring medium measurement accuracy, calibration frequency could be once every three months.
- In a situation where a gas module is operating out of specification and the appropriate troubleshooting steps have been taken, calibration would be immediate.
- Aeroqual recommends calibration be performed at least every 3 months (four times per year) but no more than once per week.
- Aeroqual is happy to work directly with you to develop a customized calibration schedule for your particular monitoring project.
- For very frequent calibrations or situations where the measurement site is a long distance away, the integrated AirCal 8000 is recommended. The AirCal 8000 can be programmed to deliver calibration gas automatically according to a schedule, or it can be manually triggered remotely using Aeroqual Cloud.
