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

The WTW SenTix H analogue special-purpose pH electrode is a sophisticated, premium-class electrochemical system solution designed specifically for high-precision measurements in the extremely high-alkalinity range and in sample media with very high salt concentrations. In traditional applications within the chemical industry, electroplating or the monitoring of industrial effluents, conventional standard electrodes often suffer from the so-called alkalinity error (sodium error) or blockages of the diaphragm. The SenTix H eliminates these sources of process error whilst minimising damage to the material, thanks to a highly specialised membrane glass formulation and mechanically optimised reference system kinetics. The system deliberately omits an integrated temperature sensor to ensure maximum robustness and thermal service life in demanding electrochemical applications.

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

The material architecture of the sensor is uncompromisingly designed for extreme pH ranges. The sensitive membrane glass is characterised by excellent selectivity, which reliably minimises measurement errors caused by high concentrations of sodium ions in strongly alkaline environments. 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 guarantees consistently high ionic activity and excellent reproducibility of measurement results, even during continuous use in aggressive chemical media.

Controlled electrolyte outflow via an adjustable ground diaphragm

An outstanding design feature of the SenTix H is the integrated ground 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, without damaging the material, rule out blockages caused by crystallisation or salt precipitation. The ground diaphragm can be easily cleaned and reactivated as required, which drastically extends the sensor’s service life in multi-user operation and guarantees 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 degrees Celsius

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 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 humidification cap with KCl storage solution
• 1 x pipette vial with refill electrolyte (3 mol/l KCl)
• 1 x Quality certificate / 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.

Customised requirements & accessories

To ensure the full performance capabilities of the WTW SenTix H in highly alkaline matrices, we stock 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 certified 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 diaphragm during measurement breaks. Please make use of our technical procurement service to tailor your industrial test setup to your specific requirements.