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• In the second case (pH value not close to the buffer)
the meter will remain in the same state until the reading
becomes unstable or the calibration mode is quitted .
• For the second buffer value it is possible to choose be-
tween pH4 .01 and pH10 .01 (or pH4 .01 and pH9 .18 if
the NIST set has been selected) . Use the
or
key to
switch between the two possibilities .
• Once selected the buffer, the procedure is the same as
for the first calibration point .
Note
A time-out of 2 .5 minutes is present for the pH electrode
response time . During calibration, if the pH reading is not
stable after 2 .5 minutes, the device displays twice the scroll-
ing message “time-out”, then shows “WRONG” and it is
not possible to complete calibration .
• At the end of calibration, with the meter set as pH con-
troller, the instrument checks if the offset is between -30
and 30 mV and the slope between 53 .5 and 62 mV/pH .
If the values are not within these ranges, the message
“OLd ProbE” scrolls twice across the LCD . The electrode
is still working, but it is necessary to perform a cleaning
procedure (see “Electrode conditioning and maintenance”
and “In-line Cleaning” sections) or replace it .
If the offset is outside the -60 to 60 mV range, the “dEAd
ProbE” message will scroll across the LCD and the cor-
responding error is activated . The electrode has to be
replaced as soon as possible because there is no reliability
on the measured pH values .
One-point calibration
A one-point calibration at a value different from the
standard buffer values is possible by entering the desired
calibration value . This is the actual pH value at the current
calibration temperature .
• Enter the pH calibration mode (no matter if the standard
or NIST buffer set is selected), then press the SETUP key
while the secondary LCD is displaying the
first buffer value (pH7 .01 or pH6 .86) .
