Servomex NanoTrace DF-760E, Instruction Manual

Page: 78 / 182

74 DF-760E User Interface
7.6.2 Oxygen Calibrate Menu
Figure 63: Oxygen Calibrate Menu
7.6.2.1 Check/Adjust Zero
Figure 64: Check/Adjust Zero Screen
It is important to note that sample line contributions to oxygen offsets in ppb
measurements, especially at the sub-ppb level, are difficult to remove even with a correctly
operating system. The dry down process of the analyzer and/or gas supply system can
literally take many months. The oxygen analyzer has an array of zeroing features that
enable the user to establish
temporary performance near 0.0 ppb during the dry down
process. Monitoring the zero 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.
This Check/Adjust Zero screen Figure 64 enables the user to pick from numerous zero
calibration related functions.
The Zero Reference value in the upper right hand corner is a reflection of the deviation
of the oxygen sensor’s present zero current from the original factory calibration based on
any user zero actions. Instruments are shipped from the factory with the zero reference set
to 0.00. After a manual or auto zero is performed, the zero reference may change.