Hanna Instruments HI 4521 - Manual (Page 49)

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mV/ORP mV/ORP mV/ORP mV/ORP mV/ORP MEASUREMENTS MEASUREMENTS MEASUREMENTS MEASUREMENTS MEASUREMENTS
Oxidation-reduction potential (ORP) measurements provide the quantification of the oxidizing or reducing power of the
tested sample.
To correctly perform a redox measurement, the surface of the ORP electrode must be clean and smooth.
DIRECT MEASUREMENT
To measure the mV of a sample using the Direct reading mode:
• Press and then to enter mV Measure mode.
• Select the Direct reading mode (see mV Setup for details).
• Submerge the tip of the ORP electrode (4 cm/1½”) into the
sample to be tested and allow a few seconds for the reading
to stabilize.
• The instrument will display the measured mV value on the LCD.
Note: If the reading is out of range, “-----” will be displayed
on the LCD.
DIRECT/AUTOHOLD MEASUREMENT
To measure mV of a sample using the Direct/AutoHold reading mode:
• Press and then to select mV Measure mode.
• Select the Direct/AutoHold reading mode (see mV Setup for
details).
• Submerge the tip of the ORP electrode approximately 4 cm
(1½”) into the sample to be tested and allow a few
seconds for the reading to stabilize.
• The measured mV value will be displayed on the LCD. If
pressing , the “AutoHold” indicator will start blinking
on the LCD until the stability criterion is reached. The mV value
will be frozen on the LCD, along with “AutoHold” indicator.
• To return to normal Measure mode press .
Note: If the reading is out of range, “-----” will be displayed
on the LCD.
mV & Relative mV MEASURE mV & Relative mV MEASURE mV & Relative mV MEASURE mV & Relative mV MEASURE mV & Relative mV MEASUREMENT MENT MENT MENT MENT SSSSS
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Temperature Compensation
The user can choose from the following options:
Linear - the meter will compensate automatically the conductivity using the following formula:
where:
C
ref
- conductivity at reference temperature
- compensation coefficient
T - temperature
ref - reference temperature
Non-Linear - recommended for measuring the conductivity of the natural water in accordance with the compensation
table on the next page.
Disabled - the meter will display the conductivity with no temperature compensation.
To set the temperature compensation mode:
• Use or to highlight the Temperature Com-
pensation option.
• Press and then use or to select
Linear, Non-Linear or Disabled option.
• Press to confirm your selection or press to cancel
operation.
Whatever form of compensation is used, the reading will not be as accurate as taking a reading of the sample’s
conductivity at the reference temperature.