Shaw SDHmini - Auto Calibration (Autocal)

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5.1 Auto Calibraon (AutoCal)
The AutoCal facility uses the fact that each sensor is designed and manufactured
to give no further increase in response when it reaches its maximum moisture
level. For example a SDHmini with a full scale value of 0 °C dewpoint will read
0 °C dewpoint when exposed to a gas with this moisture concentraon and will
connue to read 0 °C dewpoint as the moisture concentraon rises above 0 °C
dewpoint.
The SDHmini can therefore be adjusted to read 0 °C dewpoint on any gas with a
moisture concentraon weer than 0 °C dewpoint, ambient air for instance, thus
seng the span to match the original calibraon.
NOTE: For instruments with a dewpoint range above 0 °C, e.g. the Blue range, -80 to +20 °C,
please refer to secon 5.2 Calibraon Setpoint (CalSet).
Select AutoCal from the Conguraon Menu.
Please ensure that the inlet and outlet valves are open to
atmosphere.
Extend the desiccant head on the instrument (as illustrated on
the instrument screen) nocing that the value of the full scale
moisture level has already been automacally preselected as a
target of 0 °C. You may need to li the head two to three mes
to allow ambient air through to the chamber, ensuring inlet
and outlet are unrestricted. Press .
The SDHmini will display a moving bar unl it assesses that
the sensor has stabilised (please allow up to ten minutes for
this to occur).
The SDHmini will now display the full scale value of the unit,
either -20 °C or 0 °C depending on the sensor range.
Close the desiccant head when instructed to do so and press
.