User Manual
DOC022.52.80026
Refillable ORP/Redox Probe: Model MTC30101 or MTC30103
Safety information
Precautionary labels
Read all labels and tags attached to the instrument. Personal injury or damage to the
instrument could occur if not observed. A symbol on the instrument is referenced in the
manual with a precautionary statement.
Electrical equipment marked with this symbol may not be disposed of in European domestic or public disposal
systems. Return old or end-of-life equipment to the manufacturer for disposal at no charge to the user.
Specifications
Note: Specifications are subject to change without notice.
Specifications Details
Probe type Digital combination electrode with a refillable Ag/AgCl reference and a built-
in temperature sensor
Range ±1200 mV
Resolution 0.1 mV
Temperature accuracy ±0.3 °C (±0.54 °F)
Operating temperature range 0 to 80 °C (32 to 176 °F)
Storage temperature range 5 to 40 °C (41 to 104 °F)
Junction Ceramic
Reference potential versus Standard
Hydrogen Electrode
207 mV at 25 °C
Fill solution 3M KCl with saturated AgCl
Reference type Ag/AgCl (3 M KCl)
Minimum sample depth 20 mm
Dimensions Diameter: 12 mm (0.47 in.)
Length: 175 mm (6.89 in.)
Cable length: 1 or 3 m (3.28 or 9.84 ft)
Cable connection M12 digital output and connector compatible with HQd meters
Product overview
The MTC301 series probe is a refillable, combination oxidation reduction potential
(ORP/Redox) probe with a built-in temperature sensor (Figure 1). The MTC30101 or
MTC30103 probe is available with a 1 or 3 m (3.28 or 9.84 ft) cable and is intended for
laboratory use. The probe measures absolute mV values in wastewater, drinking water
and general applications. The probe measures ORP/Redox in wastewater, drinking water
and general applications. A 59 mL bottle of reference electrolyte filling solution (3M KCl
solution saturated with AgCl) is included with the probe.
1
Figure 1 Probe overview
1 Probe soaker bottle 4 Protective tape and filing-hole
2 Reference junction, platinum and temperature sensor 5 1 or 3 meter (3.28 or 9.84 ft) cable
3 Filling-hole cap 6 Probe soaker bottle holder
Preparation for use
Prepare the probe for use before calibration or sample measurement.
1. Turn the probe soaker bottle cap counter-clockwise to loosen the cap.
2. Remove the soaker bottle from the probe.
3. Rinse the reference junctions and electrode with deionized water thoroughly to
remove the viscous storage/filling solution completely. Blot dry with a lint-free cloth.
4. Remove the protective tape from the filling hole before initial use (refer to Figure 1
on page 2). Dispose of the protective tape.
5. Add filling solution to the probe as necessary (refer to Fill the probe on page 11).
The filling solution must be above the standard solution or sample level during
measurement (Figure 2).
6. Make sure that the filling hole is open during measurement for the proper flow of the
filling solution.
Figure 2 Measurement method
1 Container 3 Filling solution level
2 Probe body 4 Standard solution or sample level
2
Calibration
Before calibration:
The probe must have the correct service-life time stamp. Set the date and time in the meter before the probe is attached.
It is not necessary to recalibrate when moving a calibrated probe from one HQd meter to another if the additional meter is
configured to use the same calibration options.
To view the current calibration, push , select View Probe Data, then select View Current Calibration.
If any two probes are connected, push the UP or DOWN arrow to change to the single display mode in order to show the
Calibrate option.
Prepare the probe for use (refer to Preparation for use on page 2).
Calibration notes:
• Additional standards can be selected in the Calibration Options.
• Do not dilute ORP/Redox standards. Use fresh ORP/Redox standard for calibration.
• ZoBell’s redox potential is temperature dependent. The HQd calibration routine
factors in this temperature dependency allowing accurate calibrations within the
temperature range of 0 to 30 °C (32 to 86 °F). Light’s solution should be read at 25 °C
(77 °F). Custom ORP/Redox calibration solution values and temperature are userdefined.
• The calibration is recorded in the probe and the data log. The calibration is also sent
to a PC, printer or flash memory stick if connected.
• Air bubbles under the sensor tip when submerged can cause slow response or error
in measurement. If bubbles are present, gently shake the probe until bubbles are
removed.
• If a calibration error occurs, refer to Troubleshooting on page 12.
Calibration procedure:
1. Connect the
probe to the
meter. Make sure
that the cable
locking nut is
securely
connected to the
meter. Turn on the
meter.
2. Push
Calibrate. The
display shows the
ORP/Redox
standard solution
that is necessary
for calibration.
3. Add the fresh
ORP/Redox
standard solution
to a beaker or an
appropriate
container.
4. Rinse the
probe with
deionized water.
Blot dry with a lintfree cloth.
5. Put the probe
in the standard
solution so that
the temperature
sensor is
completely
submerged. Stir
gently. Shake the
probe from side to
side in the sample
to refresh the
reference junction.
3
6. Push Read.
Stir gently. The
display will show
"Stabilizing" and a
progress bar as
the probe
stabilizes in the
sample. The
display shows the
standard solution
value and the mV
offset when the
reading is stable.
7. Push Done to
view the
calibration
summary.
8. Push Store to
accept the
calibration and go
back to the
measurement
mode.
Sample measurement
Before measurement:
The probe must have the correct service-life time stamp. Set the date and time in the meter before the probe is attached.
If complete traceability is necessary, enter a sample ID and operator ID before measurement. Refer to the HQd meter
manual for more information.
Regular calibration is required for the best measurement accuracy (refer to Calibration on page 3).
Prepare the probe for use (refer to Preparation for use on page 2).
Make sure that the platinum disc is clean and smooth (refer to Clean the probe on page 10).
Measurement notes:
• Data is automatically stored in the data log when Press to Read or Interval is
selected in the Measurement Mode. When Continuous is selected, data will only be
stored when Store is selected.
• Air bubbles under the sensor tip when submerged can cause slow response or error
in measurement. If bubbles are present, gently shake the probe until bubbles are
removed.
• If a measurement error occurs, refer to Troubleshooting on page 12.
Measurement—direct method procedure:
4
1. Connect the
probe to the
meter. Make sure
that the cable
locking nut is
securely
connected to the
meter. Turn the
meter on.
2. To significantly
reduce the
stabilization time
for reducing-type
samples, put the
platinum disc in
Reducing Solution
for ORP
Electrodes for
3-10 minutes
before the initial
sample
measurement.
3. Rinse the probe
with the sample.
4. Put the probe in
the sample and
stir gently. Make
sure that the
reference
junctions are
completely
submerged. Do
not put the probe
on the bottom or
sides of the
container. Shake
the probe from
side to side in the
sample to refresh
the reference
junction.
5. Push Read.
The display will
show "Stabilizing"
and a progress
bar as the probe
stabilizes in the
sample. The
display will show
the lock icon when
the reading
stabilizes. If
necessary for the
application, record
the sample pH
and temperature.
6. Repeat steps
3-6 for additional
measurements.
7. When
measurements
are done, store
the probe (refer to
Storage
on page 11).
Measurement—conversion to SHE reference procedure:
For some applications, it is customary to report redox potential readings relative to the
standard hydrogen electrode (SHE), also called normal hydrogen electrode (NHE). To do
this, select the value in Table 1 that corresponds to the temperature of the solution
measured. Substitute that value Eref into the equation and solve for Eh:
Eh = E + E
ref
where:
Eh = oxidation reduction potential of the sample relative to the SHE
E = potential developed by the ORP/Redox electrode
E
ref
= potential developed by the reference electrode portion relative to the SHE
(Table 1).
Table 1 shows the potentials, E
ref
, developed by the reference electrode portion relative
to the SHE at various temperatures.
Table 1 Standard potential of reference electrode
Temperature (°C) Electrode potential in mV (E
ref
)
80 163.1
75 167.7
5
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