Xylem WTW SenTix 950 User manual

OPERATING MANUAL
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SenTix®950 / 980 /
Micro 900(-P)
pH ELECTRODE WITH LIQUID ELECTROLYTE
SenTix®950(-P)
SenTix®980(-P)
SenTix®Micro 900(-P)
OPERATING MANUAL

SenTix®950 / 980 / Micro 900(-P)
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Copyright ©2017, Xylem Analytics Germany GmbH
Printed in Germany.

SenTix®950 / 980 / Micro 900(-P) General information
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1 General information
Automatic sensor
recognition
The sensor electronics with the stored sensor data are in the connecting
head of the electrode. The data include, among other things, the sensor type
and series number. In addition, the calibration data are stored in the sensor
with each calibration and the calibration history is recorded (the last 10 cali-
brations). The data is recalled by the meter when the sensor is connected
and is used for measurement and for measured value documentation.
Storing the calibration data in the sensor ensures that the correct slope and
asymmetry are automatically used if the sensor is operated with different
meters. On the other hand, different calibrated sensors can be used with one
meter without the need to recalibrate.
The digital transmission technique guarantees the failure-free communica-
tion with the meter even with long connection cables. If the sensor firmware
is enhanced by WTW, it can be updated via the meter.

General information SenTix®950 / 980 / Micro 900(-P)
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2 Commissioning, measuring, calibration
2.1 Opening and closing the IDS plug connection
This section only applies to IDS plug variants (SenTix®... -P).
Opening the plug
connection
If necessary, clean the plug connection.
Open the locking device (step 1).
Use your thumb and index finger to press the clips of the connector
together, and pull the connector out of the plug (step 2).
Closing the plug
connection
Make sure that the plug connection is completely dry and clean.
Align the guidance of the connector with the groove in the plug and insert
the connector in the unlocked plug until it catches (step 3).
Close the locking device (step 4).
2
4
3
1
Plug connection
closed and locked
Guidance
Groove

SenTix®950 / 980 / Micro 900(-P) General information
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2.2 Commissioning
Scope of delivery Electrode SenTix®950 / 980 / Micro 900(-P)
Operating manual
Commissioning The electrode is filled with reference electrolyte solution in the factory. Pre-
pare 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 calibration and
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.
SenTix®950(-P): Remove any gas bubbles behind the pH membrane by
shaking.
Connect the electrode to the meter.
Please keep the watering cap. It is required for the electrode to
be stored. Always keep the watering cap clean.
SenTix®950 / 980 /
Micro 900
– via the sensor cable to a free IDS connec-
tor on the meter
SenTix®950 / 980 /
Micro 900-P
– via a connecting cable (accessory) to a
free IDS connector on the meter
or
– wireless via an IDS WLM-S adapter
(accessory) to a WLM-capable meter
Refilling
opening
Refilling
opening
2
1

General information SenTix®950 / 980 / Micro 900(-P)
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Calibrate the electrode according to the operating manual of the meter
and observe the following rules while doing so:
2.3 Calibration and measurement: General rules
Make sure the refilling opening for the reference electrolyte solution is
open.
Avoid the carryover of any solution (sample or buffer solution) from one
measurement to the next by taking the following measures:
– Shortly rinse the calibration and 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
water 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 com-
pletely submersed in the solution. The junction is in the area of the bottom
end of the shaft (see figure). At the same time, the level of the reference
electrolyte in the electrode must be at least 2 cm above the level of the
solution.
Provide approximately the same stirring conditions for measuring as for
calibrating.
Accessories for the connection of the
SenTix®980-P sensor to the meter: See
chapter 7 WEAR PARTS AND ACCESSORIES.
Opening and closing the IDS plug connection,
see section 2.1 OPENING AND CLOSING THE
IDS PLUG CONNECTION.
Prevent contact of the pH membrane to the beaker bottom to
avoid scratches on the pH membrane.
Junction
Reference electrolyte
(Example)
Glass membrane
Shaft

SenTix®950 / 980 / Micro 900(-P) Storage
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Subsequent
calibrations
The frequency of subsequent calibrations depends on the application. The
meters provide an option where you can enter a calibration interval. After the
calibration interval has expired, the meter will automatically remind you of the
due calibration.
3Storage
During short
measuring breaks
With the refilling opening open, immerse the electrode in reference electro-
lyte (KCl 3 mol/l, Ag+free). Prior to the next measurement, shortly rinse the
electrode with the test sample or deionized water.
Overnight or
longer
Put the clean electrode in the watering cap that is filled with reference elec-
trolyte (KCl 3 mol/l, Ag+free) and close the refilling opening.
NOTE
pH electrodes must not be stored dry or in deionized water. The elec-
trode could be permanently damaged by this. If the liquid in the
watering cap has dried up, condition the electrode in reference electro-
lyte (KCl 3 mol/l, Ag+ free) for at least 24 hours.
4 Aging
pH electrodes are consumables. Every pH electrode undergoes a natural
aging process. With aging, the responding behavior becomes slower and the
electrode slope and asymmetry change. Moreover, extreme operating condi-
tions 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.
Prevent contact of the pH membrane to the beaker bottom to
avoid scratches on the pH membrane.
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.

Maintenance and cleaning SenTix®950 / 980 / Micro 900(-P)
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5 Maintenance and cleaning
Refilling the
reference
electrolyte
During operation, a small amount of reference electrolyte leaks through the
junction from the electrode into the test sample. If the level of reference elec-
trolyte becomes too low with time, refill it through the refilling opening. Refill-
ing is very easy with the enclosed 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 the reference electrolyte in the shaft using the dropping bottle
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.
Remove other contamination as follows:
NOTE
Hydrofluoric acid, hot phosphoric acid and strong alkaline solutions
destroy the glass membrane.
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)
Proteins 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.

SenTix®950 / 980 / Micro 900(-P) Technical data
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After cleaning Rinse the electrode with deionized water and condition it in reference elec-
trolyte solution for at least 1 hour. Then recalibrate the electrode.
6 Technical data
Measurement pH measuring range 0.000 ... 14.000
Allowed temperature range
(°C)
0 ... 80 °C (SenTix®950(-P))
0 ... 100 °C (SenTix®980 / Micro 900(-P))
Allowed temperature range
(°F)
32 ... 176 °F (SenTix®950(-P))
32 ... 212 °F (SenTix®980 / Micro 900(-P))
Accuracy of the
IDS measuring
technique
Measured parameter Accuracy (± 1 digit)
pH ± 0.004
U [mV] ± 0.2
T [°C] ± 0.1
General features Reference electrolyte KCl 3 mol/l, Ag+free
Junction Ceramic (SenTix®950(-P))
Platinum (SenTix®980 / Micro 900(-P))
Temperature sensor Integrated NTC 30
(30 kat 25 °C / 77 °F)
Connection cable Lengths SenTix®950 / 980 / Micro 900: 1,5
SenTix®950 / 980 / Micro 900-P:
1,5 / 3 / 6 / 10 / 15 / 25 / 40 / 60 / 100 m
Diameter 4.3 mm
Smallest allowed
bend radius
Fixed installation:20 mm
Flexible use:60 mm
Plug type Socket, 4 pins
Shaft dimensions,
material
Shaft length 120 mm (SenTix®950 / 980(-P))
65/130 mm (SenTix®Micro 900(-P))
Shaft diameter 12 mm (SenTix®950 / 980(-P))
12/5 mm (SenTix®Micro 900(-P))
Shaft material Polyamide (SenTix®950(-P))
Glass (SenTix®980(-P),
SenTix®Micro 900(-P))

Wear parts and accessories SenTix®950 / 980 / Micro 900(-P)
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7 Wear parts and accessories
IDS plug Synthetic materials: Glass fiber reinforced
Noryl, TPU, TPC-ET, POM, PVC, PEEK,
PBT
O-ring: FPM
Contacts gold-Plated
IDS plug Connection type 4-Pole, watertight plug connection with lock,
reverse polarity protected
Storage With watering cap; filled with KCl 3 mol/L, Ag+free
Maintenance
equipment
Description Model Order no.
Reference electrolyte solution 250 ml
to fill the watering cap
(KCl 3 mol/l, Ag+-free)
KCl-250 109 705
Pepsin cleaning solution 3 x 250 ml PEP/pH 109 648
Connection cable
SenTix®950 / 980 /
Micro 900(-P) -
meter
Description Model Order no.
IDS connection cable, 1.5 m AS/IDS-1.5 903 850
IDS connection cable, 3 m AS/IDS-3 903 851
IDS connection cable, 6 m AS/IDS-6 903 852
IDS connection cable, 10 m AS/IDS-10 903 853
IDS connection cable, 15 m AS/IDS-15 903 854
IDS connection cable, 20 m AS/IDS-20 903 855
IDS connection cable, 25 m AS/IDS-25 903 856
IDS connection cable, 40 m AS/IDS-40 903 857
IDS connection cable, 60 m AS/IDS-60 903 858
IDS connection cable, 100 m AS/IDS-100 903 859
Wireless module for plug head sensor IDS WLM-S 108 141
Radio connection
SenTix®950 / 980 /
Micro 900(-P) -
meter
Description Model Order no.
WLM capable IDS meter
+ radio module for IDS meter
see Internet
Radio module for plug head sensor IDS WLM-S 108 141