Span calibration provides an option to adjust the gain of Aeroqual Type 1 sensor heads. There are no optimum span concentrations for calibrating Aeroqual sensor heads. However, there are a few considerations which can guide the decision as to which span concentration is most appropriate.
Most users buy calibration gas at the concentration to be used for the span calibration, rather than at high concentrations and diluted using a gas dilution calibrator. In this situation, you may find some limitations on what concentrations are offered by your chosen calibration gas supplier.
For some applications, measurements are made close to the monitor’s maximum detection limit. For these applications, we suggest a span point at 80 % of full scale. For other applications, gas levels may be important across a broad range rather than just close to the maximum exposure limit.
Other applications may make more use of the lower end of the sensor’s working range, with higher levels occurring less frequently and having less importance. The most appropriate span point depends on the intended application. If the intended application is unknown, Aeroqual suggests a span point at 80 % of full scale.
All calibration gases should be purchased in a balance of air.
| Sensor head | Suggested span point 80 % of full scale (in a balance of air) | Tubing material for gas calibration |
|---|---|---|
| *Ammonia 0-1000ppm | Factory calibration required | |
| *Ammonia 0-100ppm | Factory calibration required | |
| Carbon dioxide 0-5000ppm | 4000 | Tygon R-3606 |
| Carbon dioxide 0-2000ppm | 1600 | Tygon R-3606 |
| Carbon monoxide 0-1000ppm | 800 | Tygon R-3606 |
| Carbon monoxide 0-100ppm | 80 | Tygon R-3606 |
| Carbon monoxide 0-25ppm | 20 | Tygon R-3606 |
| Chlorine 0-10ppm | 8 | PTFE (Teflon) |
| Formaldehyde 0-10ppm | 8 | PTFE (Teflon) |
| Hydrogen 0-5000ppm | 4000 | PTFE (Teflon) |
| Hydrogen sulphide 0-100ppm | 80 | PTFE (Teflon) |
| Hydrogen sulphide 0-10ppm | 8 | PTFE (Teflon) |
| Methane 0-10000ppm | 8000 | PTFE (Teflon) |
| Nitrogen dioxide 0-1ppm | 0.8 | PTFE (Teflon) |
| Non-methane hydrocarbon 0-25ppm | 20 | PTFE (Teflon) |
| Ozone 0-10ppm | 8 | PTFE (Teflon) |
| Ozone 0-0.5ppm | 0.4 | PTFE (Teflon) |
| Ozone 0-0.15ppm | 0.12 | PTFE (Teflon) |
| Ozone 0-0.05ppm | 0.04 | PTFE (Teflon) |
| **Ozone 0-30 ppm | 15 | PTFE (Teflon) |
| Ozone 0-10 ppm | 8 | PTFE (Teflon) |
| *Particulate matter PM10 / PM2.5 | Factory calibration required | |
| *Particulate matter PM1 / PM2.5 / PMrsp / PM10 / TSP | Hot Swap or Factory calibration required | |
| *Perchloroethylene 0-200ppm | Factory calibration required | |
| Sulphur dioxide 0-100ppm | 80 | PTFE (Teflon) |
| Sulphur dioxide 0-10ppm | 8 | PTFE (Teflon) |
| Volatile organic compounds 0-500ppm | 400 | PTFE (Teflon) |
| Volatile organic compounds 0-25ppm | 20 | PTFE (Teflon) |
| Volatile organic compounds 0-2000ppm | 1600 | PTFE (Teflon) |
| Volatile organic compounds 0-30ppm | 24 | PTFE (Teflon) |
*Ammonia, perchlorethylene and particulate sensor heads can’t be span calibrated in the field. These must be factory calibrated.
**0-30 ppm ozone has a slightly lower value as most facilities aren’t able to generate above 15 ppm +/- 1 ppm.