17
I
A120/130
mV Measurement
1. Rinse the ORP electrode with distilled water. Place the electrode
into the sample solution and stir gently. Note, the sensing
element and liquid junction must be completely immersed into
the solution.
2. If the Auto-Read option in the setup menu is enabled, the meter
will automatically sense a stable reading and lock measurement,
the Hold icon appears on the screen. Press the key to resume
measuring.
If the option is disabled, the meter will continuously measure and
update the readings.
3. Wait for the measurement to stabilize and record the reading.
4. When all of the samples have been measured, rinse the electrode
with distilled water and soak in 4M KCl solution.
•
The ORP electrode may give unstable readings in solutions that
contain chromous, vanadous and titanous ions or other ions that
are stronger reducing agents than hydrogen or platinum.
•
To record the measurement at the predefined time intervals, refer
to the
Interval Readings
section on page 42.
Electrode Maintenance
•
Rinse the ORP electrode thoroughly with distilled water after use.
•
In the corrosive chemicals, viscous solutions and solutions with
heavy metals or proteins, take readings quickly and rinse electrode
immediately.
•
If the electrode response becomes sluggish, refer to the
instructions below to clean the electrode.
(1) Inorganic Deposits
Place the electrode in 0.1M HCl solution for 10 minutes. Rinse
the electrode with distilled water and soak in 4M KCl solution
for at least 6 hours.
(2) Oil or Grease
Place the electrode in detergent such as dishwashing liquid for
about 30 minutes. Rinse the electrode with distilled water and
soak in 4M KCl solution.
(3) If the platinum sensing element is severely contaminated, polish
the platinum surface gently with an abrasive paper of 600 grid.
Place the electrode in 0.1M HCl solution for 10 minutes. Remove
and rinse with distilled water, then soak in 4M KCl solution for
at least 6 hours.
If the electrode does not restore normal performance, replace
the electrode.
Storing the ORP Electrode
If you do not use the electrode for long periods, store the electrode in
4M KCl solution or storage solution.
Platinum sensing element
