Zero Adjustment - Honeywell APT4000PH User Manual

Zero adjustment

Allows use of electrodes with differing nominal zero (DURAFET II pH electrodes)
Display Action
Press CAL key,
enter code 1001
Select with
edit number with
proceed with ENTER
Ready for calibration
The"CAL", and "enter" icons are
flashing
Immerse electrode in a pH 7.00
buffer.
Enter the temperature-corrected
pH value in the range 6.50 to 7.50
using the arrow keys
(see buffer table).
Confirm with ENTER.
Stability check:
The measured mV value is dis-
played.
The "hourglass" icon is flashing.
66
Remark
APT4000PH is in the
Hold mode.
key,
If an invalid code is
key,
entered, the
APT4000PH returns to
measuring mode.
Display (3 s)
If the zero offset of
the electrode is too
large (> ± 200 mV),
the CAL ERR error
message is generated.
In that case the elec-
trode cannot be cali-
brated.
Note:
Stability check can be
stopped (by pressing
CAL). However, this
reduces calibration
accuracy.
APT4000PH
Display Action
At the end of the adjustment pro-
cedure asymmetry potential [mV]
(based on 25 °C) of the electrode
are displayed. Proceed with ENTER
Security prompt.
Display of pH value (alternately
with Hold) and temperature,
"enter" flashes, Sensoface is
active.
Place electrode in process.
Press ENTER to end the
zero point calibration.
Information on zero adjustment
After having adjusted the nominal zero point, be sure to calibrate the electrode
following one of the procedures as described on the next pages:
• Automatic calibration with Calimatic
• Manual calibration
• Data entry of premeasured electrodes
Remark
These is not the final
electrode value!
Zero and slope must
be determined with a
complete 2-point cali-
bration (cal 1100)
(see following pages).
After end of calibra-
tion, the outputs
remain in Hold mode
for approx. 20 sec.
67