Xylem WTW SenTix HW-T 900 User manual

OPERATING MANUAL
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SenTix®HW-T 900(-P)
pH ELECTRODE WITH LIQUID REFERENCE SYSTEM AND GROUND JUNCTION
OPERATING MANUAL

SenTix®HW-T 900(-P)
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Copyright © 2021, Xylem Analytics Germany GmbH
Printed in Germany.

SenTix®HW-T 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
calibrations). 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
communication with the meter even with long connection cables. The sensor
firmware can be updated via the meter.

General information SenTix®HW-T 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®HW-T 900(-P) General information
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2.2 Commissioning
Scope of delivery Electrode SenTix®HW-T 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.
Connect the electrode to the meter
Calibrate the electrode according to the operating manual of the meter.
When doing so, observe the general rules on the following page.
Ground junction of
SenTix®HW-
T 900(-P)
With the ground junction of the SenTix®HW-T 900 (-P) electrodes, the elec-
trode outflow can be adjusted with a thread:
Hold the electrode with the pH glass membrane pointing downward. Using
the provided special wrench, open the ground junction until some electro-
lyte solution can be seen to come out of the junction and all ground sur-
During longer storing periods, salt sediments may develop on the
watering cap and the refilling opening. The salt sediments do not
affect the measuring characteristics.
Remove any salt sediments with deionized water.
Refill the reference electrolyte solution when the filling level is
low (see chapter section 5 MAINTENANCE AND CLEANING).
Please keep the watering cap. It is required for the electrode to
be stored. Always keep the watering cap clean.
Refilling
opening
Refilling
opening
2
1

General information SenTix®HW-T 900(-P)
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faces are completely moist.
Carefully and using little power close the junction until the contact between
the rough ground surfaces can be noticed as a resistance. The electrode
is now ready to measure.
NOTE
Caution: Always use very little power to close the junction so the
ground surfaces are not damaged!
The ground junction can be opened further so that more electrolyte solu-
tion comes out.
Preparing the
sensor for
measurement
2.3 Calibration and measurement: General rules
Make sure the refilling opening for the reference electrolyte solution is
open.
Avoid the displacement 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
Specialwrench
Ground junction
OpenClose
SenTix®HW-T 900 Connect the sensor to the meter.
The sensor is immediately ready to measure.
SenTix®HW-T 900-P Connect the sensor to a free IDS sensor plug-in
position of the multi parameter probe or to an IDS
connection of the meter. To open and close the
IDS plug-in position please note the section 2.1
OPENING AND CLOSING THE IDS PLUG CONNECTION.
The sensor is immediately ready to measure.
Connection cables in different lengths to connect
the SenTix®HW-T 900-P sensor to the meter are
listed in chapter 7 WEAR PARTS AND ACCESSORIES.
Connect the sensor to the meter.
The sensor is immediately ready to measure.

SenTix®HW-T 900(-P) Storage
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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 ground junction must be
completely submersed in the solution. At the same time, the level of the
reference electrolyte must be at least 2 cm above the level of the solution.
Provide approximately the same stirring conditions for measuring as for
calibrating.
Subsequent
calibrations
The frequency of subsequent calibrations depends on the application. Many
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
electrolyte (KCl 3 mol/L, Ag+ free). Observe the minimum depth of
immersion. 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
electrolyte (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.
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 and the refilling opening. The salt sediments do not
affect the measuring characteristics.
Remove any salt sediments with deionized water.
Refill the reference electrolyte solution when the filling level is
low (see chapter section 5 MAINTENANCE AND CLEANING).

Aging SenTix®HW-T 900(-P)
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4Aging
pH electrodes are consumables. Every pH electrode undergoes a natural
aging process. With aging, the responding behavior becomes slower and
slower and the electrode slope and asymmetry change. Moreover, extreme
operating conditions can considerably shorten the lifetime of the electrode.
Extreme operating
conditions
NOTE
pH electrodes must not be operated under extreme operating condi-
tions. The electrode could be permanently damaged by this.
Examples for extreme operating conditions:
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.
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
if necessary.

SenTix®HW-T 900(-P) Technical data
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Cleaning Remove water-soluble contamination by rinsing with deionized water.
Remove other contamination as follows:
If you want to clean and rinse the ground junction, you can open it as follows:
completely unscrew the ground stopper (see figure on page 5).
After cleaning Rinse the electrode with deionized water and condition it in reference
electrolyte solution for at least 1 hour. Then recalibrate the electrode.
6 Technical data
Contamination Cleaning procedure
Fat and oil Rinse with water containing household
washing-up liquid
Lime and hydroxide depos-
its
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.
Hydrofluoric acid, hot phosphoric acid and strong alkaline
solutions destroy the glass membrane.
Measurement pH measuring range 0.000 ... 14.000
Allowed temperature range 0 ... 60 °C

Wear parts and accessories SenTix®HW-T 900(-P)
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7 Wear parts and accessories
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 Ground
Temperature sensor Integrated NTC 30
(30 kat 25 °C / 77 °F)
Connection cable Lengths SenTix®HW-T 900: 1,5
SenTix®HW-T 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 170 mm
Shaft diameter 12 mm
Shaft material Glass
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
(KCl 3 mol/L, Ag+ free)
KCl-250 109 705
Pepsin cleaning solution 3 x 250 ml PEP/pH 109 648