2-18
OXYGEN Calibration
NOTE: If this is the first calibration after the sensor element is replaced,
perform an "Initial Calibration."
Oxygen calibration is slightly different from other gases. When the
ZERO function is performed, the 30-second countdown is omitted
because the Ultima/Ultima X Series unit performs the zero
electronically. No calibration cap or zero gas is necessary.
To meet the specification stated, it is necessary to span the oxygen
Ultima/Ultima X Series Gas Monitor with the Calibration Kit and an
oxygen cylinder. The concentration of oxygen in air varies slightly due to
changing relative humidity and pressure levels. These variations in
oxygen levels are detected by the oxygen Ultima/Ultima X Series Gas
Monitor. To meet the reproducibility specification, it is necessary to use
a calibration gas cylinder. This ensures the same concentration of
oxygen for every calibration.
25% Oxygen Ultima/Ultima X Series Gas Monitor
For the SPAN function, ambient air is generally adequate for the 25%
oxygen Ultima/Ultima X Series Gas Monitor as the expected default
span value is 20.8%. Therefore, when the display prompts "APPLY
SPAN GAS" it would be adequate to simply allow the countdown to
occur without applying gas.
NOTE: If the sensor is located in an area of normally low or enriched
oxygen, then a 20.8% oxygen sample must be applied when
the display prompts: "APPLY SPAN GAS".
XIR Calibration
Although a full calibration (zero and span) can be performed on the
Ultima XIR Gas Monitor, a no-gas calibration is sufficient to properly
calibrate the monitor. Typically, a zero adjustment is all that is required
for a full calibration. Normally, any degradation of the sensor's
performance is associated with slight drifts in its zero response which, in
turn, will adversely affect its span performance. Restoring the sensor's
zero is typically sufficient to restore its span performance.
A zero adjustment is performed by one of the following methods:
• pressing the ZERO button on the Calibrator or Controller
• using the optional push-button calibration as outlined in Appendix
A, "Optional Push-button Calibration"
• using the HART Controller or DCS, as described in Appendix D.
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