Servomex NanoTrace DF-760E, Инструкция по эксплуатации

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User Interface DF-760E 75
User
Zero Offset
: Upon initial startup of the analyzer, and whenever the electrolyte is
changed, the electrolyte itself causes a higher current to flow than normal. As the
electrolyte ages (~ 3 weeks) the zero current gradually decreases. To prevent this decrease
from causing a display of negative oxygen concentration, the
User Zero Offset
can be
used. This value does not effect zero calibration; it is simply added to the calibrated zero.
Zero Gas Valves
: Can be toggled OPEN or CLOSED. This function allows manual
control of the zero gas valves.
Manual Zero
: This option enables the user to perform a re-zero of the oxygen sensor’s
output. See page 75.
AutoZero
: This option initiates a sequence to automatically perform a calibration between
the electronic zero and the sensor, accept the new calibration data, and then automatically
return the analyzer to the process measurement mode. See page 76.
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.
7.6.2.1.1 Do A Manual Zero
Figure 65: Oxygen Manual Zero
The manual zero command enables the user to zero the oxygen sensor in an interactive
manner.
NOTE: If oxygen is included in the background gas calculation, see page 103, the oxygen
sensor automatically isolated and 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 process inlet.
For the purpose of a manual zero operation, it is necessary to ensure that oxygen free gas is
entering the sensor. This can be accomplished by opening the zero gas valves for the
oxygen sensor. See Figure 64 above. When switching to a gas that is oxygen free, it is
important to wait a period necessary to allow the reading to re-stabilize.