Section 4
|
Calibration and Measurement
RmV Measurement Procedure
1. Rinse the electrode (ATC probe, stirrer probe and reference electrode, if applicable) with
distilled water, blot dry and place the electrode into the sample.
2. If the stirrer probe is in use, press the stirrer key to turn on the stirrer probe. Press the
▲ / ▼ keys to adjust the speed of the stirrer probe.
3. Wait for the measurement to stabilize and record the relative mV and temperature of the
sample when the meter indicates that the measurement is stable. The read type selected in
the EZ Startup menu or setup menu will determine how the relative mV measurements are
displayed by the meter. The available read types are Auto-Read, on ready, at time intervals,
continuous, value change in measurement and timed reading. To review or change the
available read type, refer to the
Setup Menu
section.
4. If the stirrer probe is in use, press the stirrer key to turn off the stirrer probe.
5. Remove the electrode(s) from the sample, rinse with distilled water, blot dry, place the
electrode(s) into the next sample.
6. Repeat steps 2 through 5 for all of the samples.
7. When all of the samples have been measured, store the electrode(s) according to the
instructions in the electrode user guides.
ORP Calibration Hints
The millivolt reading of an ORP standard is dependent on the reference system, reference
material and filling solution of the ORP electrode and the temperature of the ORP standard. The
ORP electrode can be automatically calibrated to read 420 mV relative to the Standard
Hydrogen Electrode (E
H
) at 25 °C when the Thermo Scientific Orion ORP standard (Cat. No.
967901 or Cat. No. 967961), Thermo Scientific Orion ORP electrode (Cat. No. 9678BNWP,
9778BNWP, 9180BNMD or 9179BNMD) and 4 M KCl filling solution (Cat. No. 900011) or 4 M
KCl gel (in Cat. No. 9179BNMD) are used. The raw mV reading of an electrode with the same
conditions is 220 mV at 25 °C.
The Orion ORP standard is stable and will not change over time, so it is an ideal standard for
any ORP measurement system. The Orion Dual Star meter offers a simple, automatic
calibration to the E
H
value in the ORP mode when using Orion ORP electrodes and standard.
Visit
www.thermoscientific.com/water
for ORP application notes that include a table of ORP
standard values at different temperatures.
•
The measurement mode (displayed to the right of the measurement value) determines the
type of calibration that the meter will perform. Set the measurement mode to ORP for the
channel that will be calibrated. Refer to the
Setup Menu
section for instructions on setting
the measurement mode.
•
Prepare and condition the ORP electrode per the instructions in the electrode user guide.
42
|
Orion Dual Star pH/ISE Benchtop
Meter User Manual
Thermo Scientific
Calibration
and Measurement
|
Section 4
Thermo Scientific
Orion Dual Star pH/ISE Benchtop Meter User Manual
|
43
•
Make sure that the ORP electrode, ATC probe and reference electrode (if applicable) are
connected to the meter inputs that correspond with the channel that will be calibrated.
•
The meter will automatically recognize the Orion ORP standard during an ORP calibration.
Always use a freshly prepared ORP standard for calibration. Allow the standard and
samples to come to the same temperature for precise measurements.
ORP Calibration Procedure
Note: In most calibration screens, press the f1 (escape) key to return to the measurement
mode without saving the calibration.
1. In the measurement mode, press the cal key.
2. Dual channel display only: Press the ▲ / ▼ keys to select the channel to be calibrated and
press the f2 (accept) key.
3. Rinse the ORP electrode (ATC probe, stirrer probe and reference electrode, if applicable)
with distilled water, blot dry with a lint free tissue and place the electrode(s) into the
standard.
4. When the electrode and standard are ready, press the f3 (start) key.
5. Wait for the value to stabilize and the meter to display ready next to the E
H
value. If the raw
mV reading of the electrode is 220 mV ± 60 mV, the meter will automatically calculate and
display the E
H
value for the electrode at the measured temperature. Press the f2 (accept)
key to accept the E
H
value.
6. The meter will display the mV offset. Perform one of the following actions:
Important Note: The
f2 (log/print) key must be pressed to save the
calibration. Only pressing the f3 (cal done) key without pressing the
f2 (log/print) key will not save the calibration.
a. Press the f2 (log/print) key to save and end the calibration, export the calibration data to
the calibration log and export the calibration data to a printer or computer, if a printer or
computer is connected to the meter and enabled in the setup menu. The meter will
automatically proceed to the measurement mode.
b. Press the f1 (escape) key to return to the measurement mode without saving the
calibration.
7. Proceed to the ORP Measurement Procedure section.