HH2500C Water Online Process pH Sensor for Complex and Aggressive Process Electrode | Cylindrical Acid/Alkali-Resistant Glass Membrane

The HH2500C is a combination pH electrode developed for complex process liquids where the sample composition can contaminate the reference system, alter the liquid-junction potential, or shorten the operating life of a conventional general-purpose electrode.

Its distinguishing feature is a customized PCG polymer-gel electrolyte selected according to the intended process chemistry. This allows the reference system to be configured for media containing high salt concentrations, heavy-metal ions, organic matter, ammonium compounds, proteins, or other challenging components.

A double-junction reference system provides an additional separation barrier between the process and internal reference element. The standard multi-porous ceramic junction creates several ionic contact paths with the sample, while optional dual-point, triple-point, and ring-shaped PTFE arrangements are available for different contamination and flow conditions.

The HA pH-sensitive glass membrane supports measurement across pH 0–14 in compatible acidic and alkaline aqueous media. A PG13.5 connection, selectable insertion lengths, and multiple detachable connector formats allow integration into immersion, inline, and retractable process assemblies.

Standard configurations operate at pressures up to 3 bar. An enhanced construction is available for applications requiring pressures up to 6 bar, subject to the applicable temperature, holder, seals, and installation conditions.

Key benefits

• Application-specific electrolyte: PCG polymer-gel formulation can be selected for the intended process chemistry.
• Designed for complex aqueous media: Suitable for evaluating applications involving salts, metals, organics, ammonium, or proteins.
• Double-junction reference: Adds a second barrier between the process and internal reference element.
• Multi-porous ceramic junction: Provides multiple ionic contact paths with the sample.
• HA process-glass membrane: Intended for compatible acid- and alkali-containing liquids.
• Flexible process integration: PG13.5 connection and insertion lengths from 120 to 425 mm.
• Optional reinforced pressure construction: Available for process pressures up to 6 bar.

Configuration options

• Application-specific electrolyte: Selected according to the sample composition and expected contaminants.
• Insertion length: Selectable from 120 to 425 mm.
• Junction configuration: Single-, dual-, or triple-point ceramic junctions, or a ring-shaped PTFE junction.
• Enhanced pressure construction: Available for process pressures up to 6 bar.
• Connector configuration: Multiple detachable 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 selection notes

The sample composition should be reviewed before ordering so that the appropriate reference electrolyte and junction configuration can be selected. Important information includes the principal ions, concentration, pH range, organic content, solids, temperature, pressure, cleaning chemicals, and expected contaminants.

An application-specific electrolyte can improve compatibility with the process, but it does not make the electrode maintenance-free. Protein-rich, oily, dye-containing, or solids-heavy media may still require regular inspection and cleaning.

For chlor-alkali processes, confirm compatibility with concentrated caustic, chlorine, hypochlorite, elevated temperature, and the relevant process pressure. Strong oxidising media can affect the reference system, seals, cable, and holder even when the pH glass itself remains responsive.

High-salinity samples can produce significant liquid-junction effects. Passing a buffer calibration does not by itself confirm measurement accuracy under actual process conditions; representative online verification is recommended.