xylem SenTix 51 PH Electrodes Owner’s Manual

xylem SenTix 51 PH Electrodes

Specifications

Reference Electrolyte	KCl 3 mol/L, Ag+ free
Junction	Ceramic, Platinum
Special Features	Plastic shaft, Longer shaft, Micro combination electrode
pH Measuring Range	0 to 14
Typical Applications	Field and Laboratory
Shaft Material	Polyamide, Glass
Cable Length	1m

Product Usage Instructions

Commissioning
The electrode comes pre-filled with reference electrolyte solution. To prepare for measuring:

1. Open the refilling opening for the reference electrolyte solution. Ensure it remains open during calibration and measurement.
2. Depending on the model, the stopper of the refilling opening may be an elastomer stopper or a slider.

Measuring
Follow these steps to measure pH using the electrode:

1. Ensure the electrode is properly connected to the meter.
2. Immerse the electrode in the sample solution.
3. Allow time for the reading to stabilize.
4. Record the pH value displayed on the meter.

Calibration
To calibrate the electrode:

1. Prepare calibration solutions of known pH values (typically pH 4.01, 7.00, and 10.01).
2. Immerse the electrode in each calibration solution and adjust the meter accordingly.
3. Rinse the electrode between each calibration point.

Technical data

General data

Model	Reference electrolyte	Junction	NTC	Special features
SenTix® 51	KCl 3 mol/L, Ag+ free	Ceramic	NTC 30 kOhm	Plastic shaft
SenTix® 52	KCl 3 mol/L, Ag+ free	Ceramic	NTC 30 kOhm	Plastic shaft
SenTix® 57	KCl 3 mol/L, Ag+ free	Ceramic	NTC 10 kOhm	Plastic shaft
SenTix® 60	KCl 3 mol/L, Ag+ free	Platinum	No
SenTix® 61	KCl 3 mol/L, Ag+ free	Platinum	No
SenTix® 62	KCl 3 mol/L, Ag+ free	Platinum	No
SenTix® 81	KCl 3 mol/L, Ag+ free	Platinum	NTC 30 kOhm
SenTix® 82	KCl 3 mol/L, Ag+ free	Platinum	NTC 30 kOhm
SenTix® 83	KCl 3 mol/L, Ag+ free	Platinum	Pt 1000
SenTix® 84	KCl 3 mol/L, Ag+ free	Platinum	Pt 1000
SenTix® 85	KCl 3 mol/L, Ag+ free	Platinum	Pt 1000
SenTix® 86	KCl 3 mol/L, Ag+ free	Platinum	NTC 30 kOhm
SenTix® 87	KCl 3 mol/L, Ag+ free	Platinum	NTC 30 kOhm
SenTix® 91	KCl 3 mol/L, Ag+ free	Platinum	NTC 30 kOhm	Longer shaft
SenTix® Mic	KCl 3 mol/L, Ag+ free	Ceramic	No	Half micro combination electrode
SenTix® MIC-B	KCl 3 mol/L, Ag+ free	Platinum	No	Micro combination electrode
SenTix® MIC-D	KCl 3 mol/L, Ag+ free	Platinum	No	Micro combination electrode

Measurement and application characteristics

Model	pH measur- ing range	Allowed tempera- ture range	Membrane resis- tance at 25 °C	Typical application
SenTix® 51	0 … 14	0 … 80 °C	< 1 GOhm	Field
SenTix® 52	0 … 14	0 … 80 °C	< 1 GOhm	Field
SenTix® 57	0 … 14	0 … 80 °C	< 1 GOhm	Field
SenTix® 60	0 … 14	0 … 100 °C	< 600 MOhm	Laboratory
SenTix® 61	0 … 14	0 … 100 °C	< 600 MOhm	Laboratory
SenTix® 62	0 … 14	0 … 100 °C	< 600 MOhm	Laboratory
SenTix® 81	0 … 14	0 … 100 °C	< 600 MOhm	Laboratory
SenTix® 82	0 … 14	0 … 100 °C	< 600 MOhm	Laboratory
SenTix® 83	0 … 14	0 … 100 °C	< 600 MOhm	Laboratory
SenTix® 84	0 … 14	0 … 100 °C	< 600 MOhm	Laboratory

SenTix® 85	0 … 14	0 … 100 °C	< 600 MOhm	Laboratory
SenTix® 86	0 … 14	0 … 100 °C	< 600 MOhm	Laboratory
SenTix® 87	0 … 14	0 … 100 °C	< 600 MOhm	Laboratory
SenTix® 91	0 … 14	0 … 100 °C	< 600 MOhm	Laboratory
SenTix® Mic	0 … 14	0 … 100 °C	< 700 MOhm	Laboratory
SenTix® MIC-B	0 … 14	-5 … 100 °C	< 1 GOhm	Laboratory
SenTix® MIC-D	0 … 14	-5 … 100 °C	< 1 GOhm	Laboratory

Shaft dimensions, shaft material, electrical connection

Model	Shaft			Electrical connection
	Length [mm]	Ø [mm]	Material	Electrode connection	Meter con- nection	Cable length
SenTix® 51	120	12	Polyamide	Fixed cable	DIN*+banana	1 m
SenTix® 52	120	12	Polyamide	Fixed cable	BNC+banana	1 m
SenTix® 57	120	12	Polyamide	Fixed cable	BNC+jack	1 m
SenTix® 60	120	12	Glass	S7 plug-in connector	depending on S7 cable****
SenTix® 61	120	12	Glass	Fixed cable	DIN*	1 m
SenTix® 62	120	12	Glass	Fixed cable	BNC	1 m
SenTix® 81	120	12	Glass	Fixed cable	DIN*+banana	1 m
SenTix® 82	120	12	Glass	Fixed cable	BNC+banana	1 m
SenTix® 83	120	12	Glass	Fixed cable	DIN*+banana	1 m
SenTix® 84	120	12	Glass	Fixed cable	BNC+banana	1 m
SenTix® 85	120	12	Glass	Fixed cable	BNC+2x banana	1m
SenTix® 86	120	12	Glass	Fixed cable	BNC+Cinch	1 m
SenTix® 87	120	12	Glass	Fixed cable	BNC+jack	1 m
SenTix® 91	170	12	Glass	Fixed cable	DIN*+banana	1 m
SenTix® Mic	40/80**	12/5**	Glass	S7 plug-in connector	depending on S7 cable****
SenTix® MIC-B	96***	3	Glass	Fixed cable	BNC	1 m
SenTix® MIC-D	96***	3	Glass	Fixed cable	DIN*	1 m

• Coaxial plug according to DIN 19262
• Stage geometry
• Measured from upper level of built-in grinding (standard grinding NS 7,5)
• Connection cable not included in the scope of delivery of the combination electrode (see WEAR PARTS AND ACCESSORIES)

Commissioning, measuring, calibration

Commissioning
The electrode is filled with reference electrolyte solution in the factory. Prepare the electrode for measuring as follows:

• Open the refilling opening for the reference electrolyte solution. Depending on the model, the stopper of the refilling opening is an elastomer stopper 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.
• Please keep the watering cap. It is required for the electrode to be stored. Always keep the watering cap clean.
• SenTix® 51, SenTix® 52, and SenTix® Mic: Remove any gas bubbles behind the pH membrane by shaking. With all other combination electrodes, gas bubbles behind the pH membrane are not a problem.
• Connect the combination electrode to the meter.
• Calibrate the electrode according to the operating manual of the meter and observe the following rules while doing so:

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 beakers are to be filled with next.
  • Between measurements, rinse the electrode with the solution that follows.
• 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 completely 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 must be at least 2 cm above the level of the solution.

Prevent contact of the pH membrane to the beaker bottom to avoid scratches on the pH membrane.

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.

Storage

During short measuring breaks
With the refilling opening open, immerse the electrode in reference electrolyte (KCl 3 mol/L, Ag+ free). Prior to the next measurement, shortly rinse the electrode with the test sample or deionized water. Prevent contact of the pH membrane to the beaker bottom to avoid scratches on the pH membrane.

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 electrode could be permanently damaged by this. If the liquid in the watering cap has dried up, condition the electrode in reference electrolyte (KCl 3 mol/L, Ag+ + free) for at least 24 hours.

During longer storing periods, salt sediments may develop on the watering cap and on the refilling opening. They do not affect the measuring characteristics and can easily be removed with deionized water when the electrode is put into operation again.

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 conditions can considerably shorten the lifetime of the electrode. These are:

• Strong acids or lyes, hydrofluoric acid, organic solvents, oils, fats, bromides, 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

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 electrolyte becomes too low with time, refill it through the refilling opening. Refilling 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.

Cleaning
Remove water-soluble contamination by rinsing with deionized water. Remove other contamination as follows:

Contamination	Cleaning procedure
Fat and oil	Rinse with water containing household washing-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.

Hydrofluoric acid, hot phosphoric acid and strong alkaline solutions destroy the glass membrane.

After cleaning
Rinse the electrode with deionized water and condition it in reference electrolyte solution for at least 1 hour. Then recalibrate the electrode.

Wear parts and accessories

Description	Model	Order no.
Reference electrolyte solution 250 mL (KCl 3 mol/L, Ag+ free)	KCl-250	109 705
Plastic arming for SenTix® pH electrodes	A pHLab/K	903 841
Pepsin cleaning solution 3 x 250 ml	PEP/pH	109 648
Connection cable S7 plug-in connector/DIN, 1 m	AS/DIN	108 110
Connection cable S7 plug-in connector/DIN, 3 m	AS/DIN-3	108 112
Connection cable S7 plug-in connector/BNC, 1 m	AS/BNC	108 114

Note: Detailed information on our wide range of buffer solutions and more accessories is given in the price list of the WTW catalog “Laboratory and field instrumentation”.

Disposal
Handle and dispose of all waste in compliance with local laws and regulations.

EU only: Correct disposal of this product — WEEE Directive on waste electrical and electronic equipment

• This marking on the product, accessories or literature indicates that the product should not be disposed of with other waste at the end of its working life.
• To prevent possible harm to the environment or human health from uncontrolled waste disposal, please separate these items from other types of waste and recycle them responsibly to promote the sustainable reuse of material resources.
• Waste from electrical and electronic equipment can be returned to the producer or distributor.

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Service and Returns: Xylem Analytics Germany Sales GmbH & Co. KG WTW Am Achalaich 11 82362Weilheim Germany

• Tel.: +49 881 183-325
• Fax: +49 881 183-414
• E–Mail wtw.rma@xylem.com
• Internet: www.xylemanalytics.com
• Xylem Analytics Germany GmbH Am Achalaich 11 82362Weilheim Germany

FAQ

Q: How often should I calibrate the pH electrode?
A: It is recommended to calibrate the pH electrode before each use for accurate measurements.

Q: Can I store the electrode dry?
A: No, always store the electrode in a storage solution to keep it hydrated and maintain its performance.

Documents / Resources

xylem SenTix 51 PH Electrodes [pdf] Owner's Manual BA-VAR-339336-EN, ba75737e05, SenTix 51 PH Electrodes, SenTix 51, PH Electrodes, Electrodes

References

• User Manual