XTC601 User’s Manual
30
97400 Issue 6.1, November 2020
CALIBRATION
3
CALIBRATION
3.1
Factory Calibration
The unit is factory calibrated at 5 points (per phase) to maximize the accuracy over
the desired range. The calibration generally includes Zero & Span points as well as 3
intermediate points. In the case of suppressed zero ranges the lowest concentration will
replace the Zero Point.
3.2
Field Calibration
Like all process analyzers, the XTC601 will require periodic calibration. The frequency
entirely depends on the location, application and accuracy requirements of the user. The
typical calibration period is expected to be between 1 and 3 months. If the calibration
period is in excess of 1 month Michell recommends a Zero and Span calibration. The
user should establish a calibration frequency to ensure that the reading is within the
specifications required for the process.
NOTE: It is possible to switch off the Field Calibration and revert to the
Factory Calibration. This can be useful for diagnostic purposes if the
reading is not what is expected. The unit is delivered with a factory
calibration and, as such, would not have any field calibration data. As soon
as the first field calibration is performed, the field calibration setting is
automatically switched on. To switch off field calibration refer to Section
3.7, Field Calibration Reset.
For the HCG version, the calibration settings shown apply to the currently
selected phase. In order to perform a field calibration on each phase it
will be necessary to repeat the process three times.
3.3
Before Calibration
Zero and Span gas cylinders with correct regulation and flow control should be in place
before installing and powering up the analyzer. Commissioning should include a check
with both gases and, if necessary, a field calibration performed.
All analyzers are factory calibrated using Mass Flow Controllers with an inlet pressure of
1 barg (14.5 psig) and the flow through the unit is set to 300 ml/min (0.63 scfh) with
a nominally atmospheric vent (50 to 100 mbar back-pressure). During commissioning
or routine field adjustment, the calibration gas applied to the analyzer should be at the
same pressure and flow rate as the process gas to be sampled.
Note: unless specifically factory calibrated otherwise, this analyzer should be operated
at atmospheric pressure.
