Hanna Instruments HI 84500 - Manual (Page 19)

19
Pump calibration must be performed every time the syringe, pump tube, the titrant bottle or the ORP
electrode is changed. A pump calibration is recommended before each set of titrations or after the
titrator is left idle for several hours.
• Press
MENU, select Setup and select the corresponding range according to the table below:
• Ensure the pump is primed with the correct titrant for the selected range ( HI 84500-50 Low
Range Titrant or HI 84500-51 High Range Titrant).
Sample preparation: Use a clean pipette to precisely add the appropriate amount of
HI 84500-55 Calibration Standard to a clean beaker as indicated below:
PUMP CALIBRATION PROCEDURE
e g n a R w o L e g n a R h g i H
m p p 0 . 0 4 o t 0 . 1 m p p 0 0 4 o t 0 3
Low Range (Free & Total SO
2
) - 1 mL
High Range (Free & Total SO
2
) - 10 mL
Note: Failure to use a clean pipette will result in erroneous readings.
• Fill the beaker up to the 50 mL mark with the distilled or
deionized water.
• Fill the 20 mL beaker up to the 5 mL mark with the HI 84500-60
Acid Reagent and add the contents to the 100 mL beaker.
• Add the contents of one packet of HI 84500-62 Stabilizer
Packet to the sample beaker.
• Press CAL key.
ELECTRODE CHECK PROCEDURE
Before taking any measurements with the HI 84500 minititrator, it is recommended to check
the HI 3148B ORP electrode using the following steps:
• Press Meter to enter mV mode.
• Pour roughly 15 mL of HI 7021 into a 20 mL beaker. This does not need to be exact, as
long as the PTFE junction is covered by the solution.
• Place the electrode in the solution, stir gently for a few seconds and verify the mV reading.
If the mV reading is 240 ± 20 mV this indicates the electrode is in good condition and can
be used for titrations. A mV reading of 240 ± 30 mV indicates the electrode is beginning
to drift. Follow the “Electrode Conditioning and Maintenance”, Probe Maintenance section
on page 32. If the mV reading is greater than 240 ± 40 mV replace the electrode.
• Remove the electrode from the solution and rinse thoroughly with deionized or distilled water.
Note: DO NOT PLACE THE TIP INTO THE CALIBRATION BEAKER,
PLACE THE TIP OVER A WASTE BEAKER. A SMALL AMOUNT
OF TITRANT IS DISPENSED WHEN THE PUMP RESETS.