WTW SenTix HW-T 900-P digital IDS pH special electrode, ground joint diaphragm, 103767

The WTW SenTix HW-T 900-P digital IDS pH special-purpose electrode is designed for pH measurement in low-ion or highly viscous media. Designed for use in environmental analysis, the chemical industry and in research and development laboratories, this digital glass electrode is suitable wherever conventional sensors reach their limits due to insufficient electrolyte contact. When measuring in distilled water, boiler feedwater, organic solvents, emulsions or suspensions, a controlled electrolyte flow in the reference system is important for stable potentials and reproducible results.

Intelligent IDS sensor technology and digital measurement reliability

The mechatronic system architecture of the SenTix HW-T 900-P is based on IDS (Intelligent Digital Sensors) technology. The highly sensitive analogue voltage signal from the electrode is digitised and calibrated directly within the sensor head. This transient signal processing reduces electromagnetic interference, such as that which may be induced by surrounding laboratory equipment, motors or stirring drives. The integrated data memory permanently stores the electrode’s specific serial number as well as a complete history of the last 10 calibrations. The automatic sensor evaluation system QSC (Quality Sensor Control) continuously monitors the electrode’s current condition and displays it on the IDS measuring instrument, supporting validity at every test stage.

Adjustable ground joint diaphragm and refillable liquid reference system

The materials-science-based design is specifically optimised for problematic sample matrices. The electrode features a precise, adjustable ground joint diaphragm. This ensures a comparatively high and constant flow rate of the liquid electrolyte, thereby achieving good electrical contact with the sample medium. Clogging caused by particles, oils or organic precipitates is made more difficult by the geometry of the ground core. A tried-and-tested liquid electrolyte (3 mol/l KCl) serves as the reference system; it can be easily topped up or completely replaced via a sealable opening on the upper glass shaft. This supports a fast response time and stable measured values even in media with low ion content.

Extended glass shaft and universal IDS plug-in head

For thermodynamically correct analyses, the SenTix HW-T 900-P features a built-in 30 kOhm NTC temperature sensor, which is integrated directly into the sensor tip and performs automatic, real-time temperature compensation of the pH value. A key design feature is the extended glass shaft, measuring 165 mm in length, which allows deep immersion into specialised sample vessels, necked flasks or reactors. An ergonomic feature of this variant is the universal IDS plug-in head. The sensor does not have a permanently attached cable; instead, it can be connected to the measuring station with great flexibility, either via an AS IDS connection cable or wirelessly via a WTW radio module. This protects the delicate glass system from mechanical stress caused by cable tension and improves the user’s freedom of movement.

Technical details

Measurement & sensor technology

• Sensor type: Digital IDS special-purpose pH electrode
• Model: SenTix HW-T 900-P
• pH measurement range: 0 to 14 pH
• Temperature element: Integrated NTC 30 kOhm temperature sensor
• Operating temperature range: 0 to 100 °C
• Calibration memory: Integrated memory for up to 10 calibrations
• Sensor evaluation: QSC-compatible (Quality Sensor Control)

Design & 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 joint diaphragm
• Connection head: Universal IDS plug-in head (for AS IDS cable or wireless module)
• Serial number: Stored electronically in the sensor

Operating conditions

• Maintenance: Refillable (KCl liquid replaceable)
• Main applications: Low-ion media (e.g. pure water, distilled water), emulsions, suspensions, organic solutions, deep sample vessels

Scope of delivery

• 1 x WTW SenTix HW-T 900-P digital IDS pH special electrode
• 1 x wetting cap with KCl storage solution
• 1 x vial of refill electrolyte (3 mol/l KCl)
• 1 x Quick start guide

Important note: The required IDS connection cable (e.g. AS IDS-1.5), wireless modules, pH buffer solutions and the IDS meter itself are not included in the standard scope of delivery and must be ordered separately.

Individual requirements and accessories

To make full use of the WTW SenTix HW-T 900-P’s full range of functions, we recommend operating it with a compatible WTW MultiLine or inoLab IDS meter. For the mechanical connection, we offer the suitable AS IDS-1.5 cable as well as IDS wireless modules for cable-free operation. For regular recalibration and to safeguard the metrological chain, we offer WTW technical buffer solutions (pH 4.01, pH 7.00 and pH 10.01). For regular topping up and the proper storage of the ground joint system, we recommend the original 3 mol/l KCl solution. Please use our procurement service to put together your bespoke digital measuring station.