5.5 Span Calibration
A span calibration is a calibration performed at the upper end of the instrument’s measurement range.
Ecotech recommends calibration at 80% of the full scale measurement or operating range of the
instrument.
While the instrument range is commonly set as a default 0 - 500 ppb, this is widely recognised as no
longer being valid with modern digital communication and most regulators will now recommend a
range more suited to local conditions.
The span gas can be delivered through either the Calibration Port, Sample Port or internal with the
IZS (internal zero/span) option. The IZS method is only suitable for a level 2 calibration (precision check)
not a level 1 calibration. Refer to the instructions outlined in the next three sections.
Note: Ensure that the instrument has been running for at least one hour before any calibration is
performed to ensure sufficient stability.
It is good practice to condition the sample lines prior to a span adjustment especially if the particulate
filter has been recently changed. To do this, run a high level span point of Ozone (approximately
1 - 2 ppm) to the instrument for an hour.
Reduce the level to 80% full scale and follow the relevant instructions below:
5.5.1 Calibration Port
Equipment Required
• Transfer standard (refer to Section 5.2.2 for possible options.)
• Span source
Procedure
1. Ensure a suitable span source is connected to the Calibration Port.
2. Set the span source output concentration to 80% of the instrument measurement range.
3. Open - Main Menu → Calibration Menu.
4. Select - Cal. Type → Manual - Accept.
5. Select - Span Source → External - Accept.
6. Select - Cal. Mode → Span - Accept.
7. Let the instrument stabilise, typically 15 minutes.
8. Enter - Span Calibrate O3 - (Enter the reading from the transfer standard) - Accept.
9. Select - Cal. Mode → Measure - Accept (To return to sample measure).
5.5.2 Sample Port
Equipment Required
• Transfer standard (refer to Section 5.2.2 for possible options.)
• Span source
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