HH2500 Cylindrical-Membrane pH Electrode for Chemical Processes

The HH2500 is a glass-body combination pH electrode designed for chemically challenging aqueous processes. Its cylindrical HA pH-sensitive membrane provides a larger sensing surface than a conventional bulb and is intended for general acid- and alkali-containing media.

The cylindrical membrane has a specified wall thickness of 0.2–0.4 mm. Its geometry provides broad contact with the process liquid while supporting full-range pH measurement from 0 to 14. Although reinforced for process use, the glass membrane should still be protected from direct impact, abrasive solids, and excessive installation force.

A double-junction reference system adds a second separation barrier between the process medium and internal reference element. The standard configuration uses PCG polymer-gel electrolyte with a special multi-porous ceramic junction, providing several ionic contact paths between the reference system and sample.

Standard configurations operate at pressures up to 3 bar. A reinforced version is available for process pressures up to 6 bar, subject to the applicable temperature, process holder, seals, and installation arrangement.

With a PG13.5 process connection, selectable insertion lengths, multiple cable connectors, and optional junction configurations, the HH2500 can be integrated into compatible immersion, inline, and retractable assemblies.

Key benefits

• Large-area cylindrical membrane: Provides broad contact between the HA pH glass and process liquid.
• Designed for acid and alkali processes: Suitable for compatible aqueous chemical media within the specified operating limits.
• Double-junction reference: Adds a second barrier against contamination of the internal reference element.
• Multi-porous ceramic junction: Provides multiple ionic contact paths with the sample.
• Optional reinforced pressure construction: Available for applications requiring pressures up to 6 bar.
• Flexible process integration: PG13.5 connection and insertion lengths from 120 to 425 mm.
• Configurable junction design: Ceramic and ring-shaped PTFE junction arrangements are available for different process conditions.

Configuration options

• Insertion length: Selectable from 120 to 425 mm.
• Junction configuration: Available with single-, dual-, or triple-point porous ceramic junctions, or a ring-shaped PTFE junction.
• Reinforced pressure construction: Available for process pressures up to 6 bar.
• Connector configuration: Multiple detachable cable and connector formats are available.
• Extended cable: Cable lengths up to 60 metres, subject to transmitter compatibility.
• Integrated temperature sensor: Selectable NTC, Pt100, and Pt1000 options.

Application and installation notes

“Acid/alkali-resistant” does not mean chemically inert in every medium. Confirm compatibility with the complete process composition, concentration, temperature, pressure, and exposure time.

Hydrofluoric acid and soluble fluoride can attack conventional pH glass. Strong alkalis at elevated temperatures can also accelerate glass degradation. Use an application-specific membrane where these conditions are present.

Nonaqueous solvents and low-water-content mixtures may require a specialized reference system, calibration method, and stabilization time. Do not assume conventional aqueous-buffer performance in these media.

The 6 bar reinforced rating should be checked against the operating temperature and complete installation assembly. The sensor, holder, O-rings, connector, and cable seal must all meet the required process conditions.