Servomex NanoTrace DF-760E, Instruction Manual

Page: 56 / 182

52 DF-760E User Interface
7.5.2.1.3 Do A Manual Zero
Figure 25: Moisture Manual Zero Screen
The manual zero command enables the user to zero the moisture cell in an interactive
manner.
For this purpose, it is necessary to ensure that moisture free gas is entering the sensor.
This can be accomplished by opening the zero gas valves for the moisture cell. See Figure
24. When switching to a gas that is moisture free, it is important to wait a period necessary
to allow the reading to re-stabilize.
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 moisture zero, must be done manually and the zero gas must be supplied
from the outside through the sample inlet.
After opening the zero gas valve and selecting
Do a Manual Zero
, a screen will appear
which displays a trace of the recent moisture reading. See Figure 25. 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 moisture cell and the
Zero Reference
field will be updated.
After this action, the user will be brought back to the main display.
Pressing ESC during the calibration process will abort the action and return the user to the
main display. Pressing Accept will complete the zero process, update the zero log and
return the user to the main display.
Once complete the gas valves must be returned to the original state with process gas going
directly through the sensor. See Figure 24.
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.
7.5.2.2 Do an AutoZero
The AutoZero command enables the user to zero the moisture cell in an automated manner.
In addition, the AutoZero procedure can be scheduled to run automatically by using the
AutoZero Setup procedure described on page 54.