29
TAKING REDOX MEASUREMENTS
(HI 9023C & HI 9025C only)
HI 9023C and HI 9025C have the capability to take ORP measure-
ments. An optional ORP electrode must be used to perform these
measurements.
Oxidation-Reduction Potential (REDOX) measurements provide the
quantification of the oxidizing or reducing power of the sample
tested.
To correctly perform a redox measurement, the surface of the ORP
electrode must be clean and smooth.
In order to improve performance and obtain a faster response
time, precondition your ORP electrode with reducing or oxidizing
solutions.
Generally speaking, if the ORP mV reading corresponding to the pH
value of the solution is higher than the values in the table below,
an oxidizing pretreatment is necessary; otherwise a reducing
pretreatment is necessary:
pH mV pH mV pH mV pH mV pH mV
0 990 1 920 2 860 3 800 4 740
5 680 6 640 7 580 8 520 9 460
10 400 11 340 12 280 13 220 14 160
Reducing pretreatment: immerse the electrode for a few minutes in
HI 7091.
Oxidizing pretreatment: immerse the electrode for a few minutes in
HI 7092.
When not in use, the tip of the electrode should be kept moist and
safe from any mechanical stress which might cause damage to the
glass/platinum junction.
30
If the batteries become weak:
- HI 9023C and HI 9023CN will display a
blinking additional decimal point.
- HI 9024C and HI 9025C will display
"LOW BAT".
- HI 9110, HI 9210 and HI 9210N will
display a "V" on the LCD. Note:
HIHI
HIHI
HI
91109110
91109110
9110,
HI 9210HI 9210
HI 9210HI 9210
HI 9210 and
HI 9210NHI 9210N
HI 9210NHI 9210N
HI 9210N are
supplied with the advanced "BEPS", Bat-
tery Error Preventive System, that detects a low voltage condition
in the battery. The "V" symbol is to alert the user that the
display will be shut-off after about 5 hours of use. After that,
the meter shuts down the display, preventing the taking of
erroneous measurements due to low voltage.
Battery replacement must only take place in a
non hazardous area using the battery types
specified in this instruction manual. To re-
place rundown batteries, remove the two
screws on the rear cover of the instrument
and replace all four 1.5V AA batteries with
new ones, while paying attention to the
correct polarity. Replace the cover and tighten
the two screws. The meter is reset any time
the batteries are removed. In case of any
functional problems, reset the meter by removing and reinstalling
the batteries.
pH
LOW BAT
V
BATTERY REPLACEMENT & AUTO-OFFBATTERY REPLACEMENT & AUTO-OFF
BATTERY REPLACEMENT & AUTO-OFFBATTERY REPLACEMENT & AUTO-OFF
BATTERY REPLACEMENT & AUTO-OFF
