Calibration; Redox; Cleaning And Reconditioning - HACH LANGE POLYMETRON 8350 Manual De Usuario

4 CALIBRATION

Before calibrating for the first time:
•
Shake the probe gently to remove any air bubbles from underneath the glass bulb.
•
Remove the storage cap and rinse the probe with demineralised water.
4.1 pH
Refer to the pH transmitter's instructions to select the correct calibration type.
•
Rinse the probe with the freshly prepared first buffer solution (pH 6.88 or 7.00), ideally at
the temperature of the sample to be measured.
•
Immerse the probe (to a depth of 4 to 5cm) and wait for stable measurements before
calibrating.
•
Rinse the probe, first with demineralised water and then with the second buffer solution
(pH close to that of the process, 4.00 or 9.22).
•
Immerse the probe (to a depth of 4 to 5cm) and wait for stable measurements before
calibrating.
•
Rinse the probe in demineralised water.

4.2 REDOX

•
Rinse the probe using a standard, freshly prepared quinhydrone solution, ideally at the
temperature of the sample to be measured.
•
Immerse the probe (to a depth of 4 to 5cm) and wait for stable measurements before
calibrating.
The potential is measured with respect to the Ag/AgCl reference system. Add 200mV for an
E reference potential.
H2

5 CLEANING AND RECONDITIONING

These electrodes are considered as consumable items and therefore have a limited lifespan,
largely dependant on the user's application. Under normal conditions, a typical lifespan would be
about one year.
Before replacing them, however, simply cleaning the electrodes may restore them.
Such cleaning will also be necessary whenever the following are observed:
•
An offset from zero or a measurement drift (the reference system is contaminated).
•
A significant drop in response time and a loss of slope (there is fouling on the glass diaphragm
or the platinum).
Provided the glass diaphragm is neither scratched nor cracked, follow one of the cleaning
procedures below:
•
Salt deposits: HCl 0.1M (5 mins) + NaOH 0.1M (5 mins)
•
Grease or oil film: Detergent + water
•
Reference junction fouled: KCl 3M @ 60-80 °C for 10 mins, then cool in KCl 3M@25 °C
•
Calcium, metal hydroxide or protein deposits: HCl 10% for 10 mins
•
Redox measurements:
•
Deposits/ wear: aqua regia (1/1 concentrated HCl / concentrated HNO
only be carried out by qualified individuals.
If the electrode's response is not improved, replace it.
); this process must
3
5/6