Servomex NanoTrace DF-760E, Instruction Manual

Page: 80 / 182

76 DF-760E User Interface
Use the arrows to highlight
Set Zero Gas Valves
and press
Enter
. A box will appear at
the right and the arrows can be used to select either
Open
or
Close valves.
Highlight
Open
and hit
Enter. Zero Gas Flowing
will appear at the bottom of the main display.
After selecting “
Do a Manual Zero
” a screen will appear which displays a trace of the
recent oxygen reading. See Figure 65. Observe the trace until the reading is stable and then
press
Enter
. This action will accept the present value as the new zero setting for the
oxygen sensor and the
Zero Reference
field will be updated. After this action, the user
will be brought back to the main display and the Oxygen Cal Log is updated as shown in
Figure 89.
Once complete, the gas valves must be returned to the original state with process gas going
directly through the sensor. Use the arrows to highlight
Set Zero Gas Valves
and press
Enter
. A box will appear at the right and the arrows can then be used to select either
Open
or
Close valves.
Highlight
Close
and hit
Enter. Zero Gas Flowing
will then
disappear appear from the bottom of the main display.
Pressing ESC during the calibration process will abort the action. Whether the calibration
is complete or aborted, pressing done from the previous screen will allow the user to return
to the main display and the Oxygen Cal Log is updated as shown in Figure 89.
A relay is available on the Oxygen Output Setup Screen (see page 97) to signal that a span
or zero calibration is taking place, and the analog output signal can also be frozen or
allowed to update during the calibration process.
7.6.2.1.2 Do An Auto Zero
Figure 66: Oxygen Auto Zero Screen
The AutoZero command enables the user to zero the oxygen sensor in an automated
manner. In addition, the AutoZero procedure can be scheduled to run automatically by
using the AutoZero Setup procedure described on page 77.
NOTE: If oxygen is included in the background gas calculation, see page 103, the on-
board zero gas purifier is automatically prevented from being used. As a result an
adjustment of the oxygen zero, must be done manually and the zero gas must be supplied
from the outside through the sample inlet.