5 zero adjustment for isfet probes—for si792(x) p, Hart) and si792x p-ff only, Calibration – Hach-Lange SI792 P, SI792x P, SI792x P-FF, SI792x P-PA User Manual User Manual
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Calibration
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6. Press
ENTER
to end the calibration. The display will show the
measured value alternating with Hold.
7. Press
ENTER
to return to the measuring mode. The outputs will
remain in the hold mode for approximately 20 seconds.
Note: For comparison calibration via Foundation Fieldbus, see
8.1.1.5
Zero adjustment for ISFET probes—For si792(x) P (HART)
and si792x P-FF only
The nominal zero point must be adjusted each time a new ISFET or
probe with an offset or isopotential other than pH 7 is connected. If not
adjusted, the Sensoface messages will not be accurate. Complete the
following steps to adjust the zero point.
1. Press
CAL
, enter passcode: 1001,
ENTER
. The display will show
CAL ZRO and then the pH value for the zero point.
2. Place the pH probe in a pH 7.00 buffer solution. Briefly stir the
solution with the probe.
3. Enter the temperature-corrected pH value of the buffer solution. The
value must be between 6.50 and 7.50 pH. Press
ENTER
to save
the value.
4. The transmitter will measure the mV reading of the probe. The
hourglass will flash. When complete, the mV value of the zero offset
of the probe will be displayed. Press
ENTER
.
5. Press
ENTER
to end the zero adjustment.
After adjusting the zero offset, be sure to calibrate the probe by
following one of the available procedures:
•
Automatic buffer recognition
•
Manual buffer entry
•
Product comparison method
•
Data entry