WTW SenTix H analogue special-purpose pH electrode, ground-glass diaphragm, S7 connector, 103644

The WTW SenTix H analogue special-purpose pH electrode is an electrochemical system solution designed specifically for high-precision measurements in the extreme high-alkali range and in sample media with very high salt concentrations. In traditional applications within the chemical industry, electroplating or the monitoring of industrial wastewater, conventional standard electrodes often suffer from the so-called alkali error (sodium error) or blockages of the diaphragm. The SenTix H reduces these sources of process error thanks to a highly specialised membrane glass formulation and mechanically optimised reference system kinetics. The system has no integrated temperature sensor.

Specialised glass to counteract the alkali error and for high salt concentrations

The material architecture of the sensor is designed for extreme pH ranges. The sensitive membrane glass is designed for strongly alkaline media, in which high sodium ion concentrations can affect the measurement, according to the manufacturer. A tried-and-tested liquid electrolyte (3 mol/l KCl) serves as the reference system; this can be easily topped up or completely replaced via a sealable opening at the top of the glass shaft. This supports consistently high ionic activity and good reproducibility of measurement results, even during continuous use in aggressive chemical media.

Controlled electrolyte outflow via an adjustable ground-glass diaphragm

A design feature of the SenTix H is the integrated ground-glass diaphragm. Compared with conventional ceramic or fibre diaphragms, the precisely ground glass core enables a comparatively high, continuous and precisely defined electrolyte flow. These flow dynamics prevent sample components from entering the reference system and prevent blockages caused by crystallisation or salt precipitation. The ground-glass diaphragm can be easily cleaned and reactivated as required, which can extend the sensor’s service life in multi-user operation and support a fast, stable response.

Extended geometry and flexible S7 plug-in head

The physical boundary of the system is defined by a robust glass shaft, which, with a special length of 165 mm, allows deep immersion into necked flasks, reactors, deep sample vessels or laboratory apparatus. The mechanical and electrical connection to the pH meter is made via the standardised S7 connector. As no fixed cable is fitted, the electrode can be operated with a high degree of flexibility using various cable types (e.g. S7 to DIN or S7 to BNC). This protects the delicate glass probe from mechanical stress caused by cable tension and enables the sensor to be replaced easily within the existing measurement setup without the need to re-route the entire cable infrastructure.

Technical details

Measurement & sensor technology

• Sensor type: Special analogue pH electrode
• Model: SenTix H
• pH measurement range: 0 to 14 pH (optimised for the high-alkali range)
• Temperature element: Without integrated temperature sensor
• Operating temperature range: 0 to 100 °C

Construction & dimensions

• Shaft material: Highly chemically resistant glass shaft
• Shaft length: 165 mm (extended version)
• Shaft diameter: 12 mm
• Electrolyte: Liquid electrolyte (3 mol/l KCl, refillable)
• Diaphragm: Adjustable ground-glass diaphragm
• Connection head: S7 plug-in head (without fixed connection cable)
• Geometry: Cylindrical glass membrane

Operating conditions

• Maintenance: Refillable (KCl liquid replaceable)
• Main applications: Strongly alkaline media, high salt concentrations, electroplating, process monitoring, deep laboratory vessels

Scope of delivery

• 1 x WTW SenTix H analogue special-purpose pH electrode (MPN: 103644)
• 1 x wetting cap with KCl storage solution
• 1 x pipette vial with refill electrolyte (3 mol/l KCl)
• 1 x quick start guide

Important note: A suitable S7 connection cable (e.g. AS/DIN or AS/BNC), calibration buffers and the pH meter itself are not included in the standard scope of delivery and must be ordered separately.

Individual requirements & accessories

To ensure the full performance capabilities of the WTW SenTix H in highly alkaline matrices, we offer a comprehensive range of connection components and consumables. For connection to the meter, we offer genuine WTW laboratory cables with an S7 connector head fitted to a DIN or BNC plug. For regular recalibration in the critical alkaline range, we recommend WTW technical buffer solutions (in particular pH 9.18 and pH 10.01) in handy dosing bottles. The use of genuine 3 mol/l KCl solution is essential for the regular refilling of the reference system and for the material-friendly storage of the ground-glass diaphragm during measurement breaks. Please make use of our technical procurement service to tailor your industrial test setup to your specific requirements.