wtw SenTix ORP 900 User manual

OPERATION MANUAL
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SenTix®
PH-MESSKETTE MIT FLÜSSIG-REFERENZSYSTEM UND SCHLIFFDIAPHRAGMA
SenTix®ORP 900
SenTix®ORP-T 900
OPERATING MANUAL

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SenTix®ORP 900
Copyright ©Weilheim 2014, WTW GmbH
Reprinting - even as excerpts - is only allowed with the explicit written
authorization of WTW GmbH, Weilheim.
Printed in Germany.
For the most recent version of the manual, please visit
<hyperlink>www.WTW.com.

SenTix®General information
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General information
Automatic sensor
recognition
The sensor electronics with the stored sensor data is in the connecting head
of the electrode. The data include, among other things, the sensor type and
series number. The data is recalled by the meter when the sensor is
connected and is used for measurement and for measured value documen-
tation.
The digital transmission technique guarantees the failure-free communi-
cation with the meter even with long connection cables. If the sensor firmware
is enhanced by WTW, it can be updated via the meter.
Technical data
General data Reference electrolyte 3 mol/l KCl, Ag+free
Junction Ceramic
Electrode material and shape Platinum / circle
Measurement and
application
characteristics
mV measuring range - 1250.0 ... + 1250.0
Allowed temperature range 0 ... 100 °C (32 ... 212 °F)
Typical application Laboratory
Shaft dimensions,
material, electrical
connection
Shaft length 120 mm
Shaft diameter 12 mm
Shaft material Glass
Combination electrode con-
nection
Fixed cable
Meter connection Digital plug
Connection cable Length 1.5 m
Diameter 4.3 mm
Smallest allowed bend
radius
Fixed installation: 20 mm
Flexible use: 60 mm
Plug type Socket, 4 pins
Accuracy of the
IDS measuring
technique
Measured parameter Accuracy (± 1 digit)
U [mV] ± 0.2
T [°C] (SenTix®ORP-T 900) ± 0,1

Commissioning, measuring, checking SenTix®
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Commissioning, measuring, checking
Commissioning Prepare the electrode for measuring as follows:
Open the refilling opening for the reference electrolyte solution. Depend-
ing on the model, the stopper of the refilling opening is an elastomer stop-
per or a slider.
The refilling opening must always be open during measurement!
Remove the watering cap from the electrode tip. Possible salt deposits in
the area of the watering cap do not affect the measuring characteristics
and can easily be removed with deionized water.
Connect the combination electrode to the meter.
Measure with the electrode according to the operating manual of the meter
and observe the following rules while doing so:
General rules for
measuring
Make sure the refilling opening for the reference electrolyte solution is
open.
Avoid the carryover of sample solution from one measurement to the next
as follows:
– Shortly rinse the sample beakers with the solution the beakers are to
be filled with next.
– Between measurements, rinse the electrode with the solution that fol-
lows. Alternatively, you can also rinse the electrode with deionized wa-
ter and then carefully dab it dry.
Immerse the electrode in the solution in a vertical or slightly tilted position.
Make sure the immersion depth is correct. The junction must be complete-
ly submersed in the solution. The junction is in the area of the bottom end
For ORP electrodes with platinum electrode, please follow the
instructions in section ACTIVATING PLATINUM ELECTRODES.
Please keep the watering cap. It is required for the electrode to
be stored. Always keep the watering cap clean.
Refilling
opening

SenTix®is temperature dependent and can be taken from the following tableStorage
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of the shaft (see arrow).
At the same time, the level of the reference electrolyte must be at least 2
cm above the level of the solution.
Conversion to
normal hydrogen
electrode
UH= UMeas + URef
URef is temperature dependent and can be taken from the following table (see
also DIN 38404-6):
is temperature dependent and can be taken from the following tableStor-
age
During short
measuring breaks
Immerse the electrode in the reference electrolyte with the refilling opening
open.
SenTix®ORP 900
with: UH= ORP, referring to the normal hydrogen electrode
UMeas = Measured ORP
URef = Voltage of the reference system compared to the normal
hydrogen electrode
T (°C) T (°F) URef [mV] T (°C) T (°F) URef [mV]
SenTix®ORP 900 SenTix®ORP 900
0 32 +224 35 95 +200
5 41 [phone] +196
10 50 [phone] +192
15 59 [phone] +188
20 68 [phone] +184
25 77 [phone] +180
30 86 +203

Aging SenTix®
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Prior to the next measurement, shortly rinse the electrode with the test
sample or deionized water.
Overnight or
longer
Insert the clean electrode into the watering cap filled with reference
electrolyte and shut the refilling opening.
Aging
Every ORP electrode undergoes a natural aging process. Extreme operating
conditions can considerably shorten the lifetime of the electrode. These are:
Strong acids or lyes, hydrofluoric acid, organic solvents, oils, fats, bro-
mides, sulfides, iodides, proteins
High temperatures
High changes in pH and temperature.
The warranty does not cover failure caused by measuring conditions and
mechanical damage.
Maintenance and cleaning
During operation, a small amount of reference electrolyte leaks through the
junction from the electrode into the test sample. If the level of reference
electrolyte becomes too low with time, refill it through the refilling opening.
Refilling the
reference
electrolyte
Refilling is very easy using a dropping bottle. Proceed as follows:
Cut off the tip of the dropping bottle at a right angle until the opening in the
tip can be seen
Open the refilling opening of the electrode
Press the tip of the dropping bottle into the refilling opening while turning
it slightly
Pump several small quantities of the reference electrolyte into the stem
using the dropper bottle
Electrode Reference electrolyte Model
(see page 8)
SenTix®ORP 900 3 mol/l KCl, Ag+-free KCl-250 (250 ml)
SenTix®ORP-T 900
During longer storing periods, salt sediments may develop on the
watering cap. They do not affect the measuring characteristics
and can easily be removed with deionized water when the elec-
trode is put into operation again.

SenTix®Activating platinum electrodes
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Pull the dropping bottle out of the refilling opening while turning it slightly
as necessary.
Cleaning Remove water-soluble contamination by rinsing with deionized water. Re-
move other contamination as follows:
After cleaning Rinse the electrode with deionized water.
Activating platinum electrodes
First-time
activation during
installation and as
required
For first-time activation use the activation powder from the SORT/RH reagent
set (component of the SORT/RH reagent set). Immerse the moist (but not
dripping) platinum electrode into the activation powder and rotate the
electrode several times in the powder. Then remove the activation powder
under flowing water with a soft brush (e.g. toothbrush).
Activation during
very long set-up
times
When changing from oxidizing to reducing test solutions and vice versa this
can result in set-up times that can take significantly more than an hour. In this
case pretreatment (activation) of the platinum surface can shorten the set-up
time. The type of pretreatment (reducing or oxidizing) is based on the pH val-
ue and the ORP voltage (UH) of the test solution where the latter must be es-
timated for the first measurement.
Contamination Cleaning procedure
Fat and oil Rinse with water containing household wash-
ing-up liquid
Lime and hydroxide deposits Rinse with citric acid (10 % by weight)
Protein Immerse in pepsin cleaning solution PEP/pH
for approx. 1 hour.
Note: Make sure the level of the reference
electrolyte is above that of the cleaning solu-
tion.

Wear parts and accessories SenTix®
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The type of pretreatment can then be determined using the following diagram
where UHis based on the normal hydrogen electrode:
Wear parts and accessories
Oxidizing pretreat-
ment
Immerse the platinum electrode for two to three
days in a sulfuric acid clorina solution (0,5 g clorina
powder, 100 ml H2O dist., 2-3 ml 20% sulfuric acid).
Clorina powder for producing the solution is includ-
ed in the SORT/RH reagent set.
Note: The diaphragm must not be immersed in the
clorina solution!
Reducing pretreat-
ment
When the electrode is ready for the test immerse it
in the RH 28 ORP buffer solution and wait for a sta-
ble measured value.
Detailed information on activating platinum electrodes, such as
how to produce the clorina solution, is given in the WTW applica-
tion report entitled REGENERATING ORP ELECTRODES. The appli-
cation report is included in the SORT/RH reagent set.
1000
800
600
400
200
20481012146
0
pH value
UHin mV oxidizing pretreatment
reducing pretreatment
Description Model Order no.
Reference electrolyte solution 3 mol/l KCl,
Ag+free (250 ml)
KCl-250 109 705
Reagent set for regenerating ORP platinum
electrodes, consisting of 10 g activation pow-
der and 30 g clorina powder
SORT/RH 109 730
ORP buffer solution for checking ORP
electrodes UH= 427 mV, bottle of 250 ml
RH 28 109 740

SenTix®Wear parts and accessories
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Pepsin cleaning solution, 3 bottles of 250 ml
each
PEP/pH 109 648

Wear parts and accessories SenTix®
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