15
GENERAL OPERA
TIONS
5.3. ELECTRODE CONDITIONING AND MAINTENANCE
During transport tiny bubbles of air may have formed inside the pH sensor bulb. The electrode
cannot function properly under these conditions. These bubbles can be removed by “shaking down”
the electrode as you would do with a glass thermometer. If the pH bulb and/or junction are dry,
soak the probe in
HI70300
Storage Solution for at least one hour.
To ensure a quick pH response, the glass bulb and the junction should be kept moist and not
allowed to dry out. Install the probe so it is constantly immersed in the sample.
When not in use, keep the glass moist by moistening the small sponge with of
HI70300
Storage
Solution or, in its absence,
HI7082
KCl 3.5M and replace the protective cap.
IMPORTANT:
Rinse the entire probe with tap water and shake excess water from probe before
calibrating or using. The Storage solution is extremely conductive and will contaminate standards if
not removed thoroughly from the probe.
pH bulb cleaning and inspection
1. On a weekly basics, rinse the probe with tap water as preventative maintenance. Inspect
probe to ensure solids have not caked around the bulb. Bi‑monthly, a more thorough
cleaning is advised. Clean the entire
HI1285‑8
probe in
HI700661
Electrode Cleaning
Solution for Agriculture.
2. Open the
HI700661
sachet. Place opened sachet in a beaker to prevent tipping. Place the
probe in the sachet and stir the solution gently. Allow the probe to soak in the sachet 5 to 15
minutes. Rinse the entire probe thoroughly with water.
3. Shake excess water from the probe.
4. Soak the probe for 1 hour in
HI70300
storage solution. Rinse the entire probe thoroughly
with water after this procedure, as it is extremely conductive.
5. Shake excess water from the probe.
6. Recalibrate: Place the probe tip into the pH calibration standard. Wait for the reading to
stabilize as the probe equilibrates to the temperature of the solution.
7. If the probe response is slow or does not calibrate correctly, repeat the cleaning procedure.