user manual

Input Calibration
140 UDA2182 Universal Dual Analyzer Product Manual January 2009
8.5 pH Calibration
8.5.1 Introduction
pH instrument calibration consists of standardization and slope adjustments.
Standardization is a pH Offset adjustment to compensate for electrode drift. Slope
adjustment is a span adjustment to match the gain of the instrument to the electrode output
response. For Durafet III pH electrodes, initial factory default value of offset and slope are
automatically uploaded by the UDA. These values will appear in the “pH/ORP Cal”
screens Table 8-2, step 4.
The analyzer supports two methods of calibration:
• With the “Buffering” method described in this section, you use your electrode
system to measure two reference solutions (“buffers”) having known pH values,
and then adjust the analyzer so that its readings match the actual pH of each.
ATTENTION
The two reference solutions must have a pH difference of at least 2.
• With the “Sample” method described in this section you measure your process,
both with your electrode system and with a separate (accurately calibrated) meter,
then adjust the analyzer so that its reading matches the meter.
ATTENTION
When a Durafet III pH electrode is replaced, its electrode calibration data
needs to be updated by the UDA2182 Analyzer. This is done either by
power cycling the analyzer or using the restart screen.
Using the restart screen
Press Action
Display
Repeatedly until the
One Input or Two Inputs display
screen appears.
Enter
You will see:
to change to
Enter
to restart the UDA.
Was probe replaced?
No
Yes