Delta Faucet DF-745 Manuel D’Utilisation
User Interface DF-745
57
7.4.10.1
Active Zero On/Off
Figure 58: Active Zero On/Off Menu
The Active Zero Offset feature is designed to automatically compensate for the analyzer’s
gradual zero baseline cleanup. This gradual cleanup is natural and occurs after a fresh
startup or after a prolonged or abnormally high moisture exposure. This feature ensures that
accurate low ppb H
gradual zero baseline cleanup. This gradual cleanup is natural and occurs after a fresh
startup or after a prolonged or abnormally high moisture exposure. This feature ensures that
accurate low ppb H
2
O readings can be made as soon as possible after initial startup, or after
a high H
2
O upset event. It is similar to the User Zero Offset feature in that a small positive
offset is added to the analyzer H
2
O readings (display and output) to compensate for the
long term downward trending in the readings during cleanup. The Active Zero Offset
provides an automatic addition of offset that occurs in miniscule steps, and within set
guidelines, corresponding to predictable behavior during cleanup.
provides an automatic addition of offset that occurs in miniscule steps, and within set
guidelines, corresponding to predictable behavior during cleanup.
When Active Zero Offset is enabled through the Diagnostics Menu, the User Zero Offset
feature is disabled and vice versa. See page 40 for more information on the User Zero
function. While the User Zero Offset feature requires the user to enter a fixed positive offset
value to accommodate the baseline cleanup, the Active Zero Offset does so automatically,
and only when necessary.
feature is disabled and vice versa. See page 40 for more information on the User Zero
function. While the User Zero Offset feature requires the user to enter a fixed positive offset
value to accommodate the baseline cleanup, the Active Zero Offset does so automatically,
and only when necessary.
The current Active Zero Offset value is shown in the Check/Adjust Zero screen as shown in
Figure 27. It starts at a value of 0.00 ppb when the analyzer is first turned on, and then
increments automatically as the analyzer applies offset to the readings. After each User Zero
Calibration, the Active Zero Offset value is reset to 0.00 ppb and then automatically
increments again as needed.
Figure 27. It starts at a value of 0.00 ppb when the analyzer is first turned on, and then
increments automatically as the analyzer applies offset to the readings. After each User Zero
Calibration, the Active Zero Offset value is reset to 0.00 ppb and then automatically
increments again as needed.
The Active Zero Offset is designed to operate when the zero baseline is falling at a rate less
than 0.1 ppb/hr as would be the case after 1-2 weeks of initial operation. If user calibrations
are performed sooner, the H
than 0.1 ppb/hr as would be the case after 1-2 weeks of initial operation. If user calibrations
are performed sooner, the H
2
O readings may be decreasing too rapidly for the Active Zero
Offset feature to operate properly and negative H
2
O readings may result.
If the Active Zero Offset value reaches 5 ppb a warning message CAL ZERO will flash in
the system status block on the display instructing the user that a zero calibration should be
performed. The maximum amount of offset that can be applied by this feature is 5 ppb. Any
further downward trend (baseline cleanup) exceeding –0.3ppb will result in negative
readings until the next user calibration is performed resetting the Active Zero Offset value
to zero.
the system status block on the display instructing the user that a zero calibration should be
performed. The maximum amount of offset that can be applied by this feature is 5 ppb. Any
further downward trend (baseline cleanup) exceeding –0.3ppb will result in negative
readings until the next user calibration is performed resetting the Active Zero Offset value
to zero.