123 Measuring with pH & ORP Probes
21.4.2. ORP Probes Calibration
ORP calibration is a single point calibration that can be performed with the probe installed in the process or
with the probe removed from the process.
Preparation Guidelines
Probe removed from the process
• Rinse the probe with deionized water and pat it dry with a lint‑free cloth prior to calibration.
• Submerge the electrode tip (4 cm/1½”) into the sample to be tested.
• Do not let the probe touch the bottom or sides of the container.
• Remove the air bubbles from under the probe tip. Stir the sample at a slow to moderate rate and wait a
few seconds for the reading to stabilize.
Note: ORP calibration standards may be used with the probe directly i.e. 240 mV (HI7021 ORP test solution
for platinum and gold electrodes)
or 470 mV (HI7022 ORP and test solution for platinum and gold electrodes).
Probe installed in the process
• Use a calibrated portable ORP meter to determine the value of the process and write down the value.
Б
92
25.0
mV
°C
Measure ORP
Note: mV measurements are generated by the ORP electrode and displayed with 1 mV resolution.
Procedure
An ORP calibration is a single point calibration. The calibration point value is displayed, and the value can be
adjusted ± 60 mV around the measured mV.
If an ORP calibration standard is used, the probe is removed from the process, cleaned off then placed in a
beaker with the standard.
1. Press CAL when the instrument is in mV measurement mode. The mV value is displayed.
2. Press the
ud keys to adjust the value.
3.
After the reading has stabilized and the mV offset is inside the offset window, CFM virtual key is displayed.
Press CFM, to confirm ORP calibration.
The instrument will return to the main menu.
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