Servomex NanoTrace DF-760E, Инструкция по эксплуатации

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50 DF-760E User Interface
reference number during that time, or repeated restoration of the factory zero, will give the
user a sense of the offset being induced by the user zero actions.
7.5.2.1 Check/Adjust Zero
Figure 22: Moisture Check/Adjust Zero Screen
The moisture Check/Adjust Zero screen displays many pieces of information including a
live reading of moisture in ppb (or ppm) and the state of the zero gas control valves. Also
depicted are zero reference and zero offset values.
The Zero Reference value is a reflection of the deviation of the instrument’s baseline
from what was set at the factory. The zero reference of an instrument from the factory will
be 0.00. After a manual or auto zero is performed, this value may change slightly.
If the moisture cell has been previously calibrated by the user, Restore Factory Zero will
be enabled on this screen. Enacting this will erase any user zero and restore the factory set
point.
The Active Zero Offset is another offset feature. When this feature is turned on, the User
Zero Offset display is inactive and Active Zero Offset will be displayed instead. See page
67 for additional information on the Active Zero feature.
A relay is available on the Moisture Analog Output Setup Screen (see page 66) to signal
that a zero calibration is taking place, and the analog output signal can also be frozen or
allowed to update during the calibration process.
7.5.2.1.1 User Zero Offset
The User Zero Offset function enables the user to add a given moisture ppb value to the
displayed concentration. This can be useful in preventing negative readings to be
displayed should the baseline drift below the calibrated zero point. The value does not
affect zero calibration, it is simply added to the calibrated zero. For example, an offset of
1.0 ppb could be put into a system reading 0.0 ppb to allow a chart recorder attached to the
output to read slightly above zero. Under this condition, the moisture reading would be 1.0
ppb. Use the arrow keys (
and

to highlight Enter User Zero Offset in the
Check/Adjust Zero screen, Figure 22, hit the Enter key on the front panel, and the zero