HH4000 ORP Sensor Electrode| Glass Body Electrodes | 99% High-Purity Platinum Ring | Interface-compatible with Mettler Toledo ORP Models

The HH4000 is a combination ORP electrode designed for continuous oxidation-reduction potential measurement in industrial water and chemical processes. Its large-area platinum-ring measuring element provides broad contact with the process liquid and is suitable for monitoring oxidizing and reducing conditions across a specified range of −2000 to +2000 mV.

Platinum is chemically stable in many aqueous applications and provides an electrically conductive surface on which the process oxidation-reduction potential can develop. The displayed ORP value represents the combined electrochemical condition of the sample; it does not directly identify a particular oxidant, reductant, or chemical concentration.

The reference system uses PCG polymer-gel electrolyte and a double-junction construction. The second junction creates an additional separation barrier between the process liquid and internal reference element, helping slow the migration of process contaminants. A special porous-ceramic junction provides ionic contact with the sample.

The HH4000 uses a glass body with a PG13.5 process connection and is available in insertion lengths from 120 to 425 mm. Multiple connector and optional temperature-sensor configurations allow integration with compatible transmitters, holders, flow-through chambers, and retractable assemblies.

The electrode is specified for temperatures up to 130 °C. Standard configurations operate at pressures up to 3 bar, while reinforced versions may support pressures up to 6 bar, subject to the applicable temperature and complete assembly rating.

Key benefits

• Large platinum measuring surface: Ring geometry provides broad contact between the platinum and process liquid.
• Wide ORP range: Supports measurement of strongly reducing and strongly oxidizing process conditions.
• Double-junction reference: Adds a second barrier between the process and internal reference element.
• High-temperature construction: Intended for compatible aqueous processes at temperatures up to 130 °C.
• Configurable junction: Single-, dual-, and triple-point ceramic arrangements are available.
• Flexible integration: PG13.5 connection, several insertion lengths, and multiple connector formats.
• Optional temperature measurement: NTC, Pt100, and Pt1000 elements can be integrated for process-temperature monitoring.

Configuration options

• Insertion length: Selectable from 120 to 425 mm according to the process holder.
• Junction configuration: Standard single-point porous ceramic, with dual- or triple-point versions available.
• Reinforced pressure construction: Available for applications requiring pressures above the standard 3 bar rating.
• Connector configuration: S8, S8M, S7, VP8, K8S, K2, and other compatible formats.
• Extended cable: Cable lengths up to 60 metres, subject to transmitter and installation compatibility.
• Integrated temperature element: Selectable NTC, Pt100, and Pt1000 options.

Measurement and installation notes

ORP is an empirical potential determined by the complete sample chemistry, measuring surface, reference electrode, temperature, mixing, and stabilization time. It should not be interpreted as a direct concentration measurement without a validated process-specific relationship.

Coatings, oils, sulfides, proteins, metal deposits, and suspended solids can alter the platinum surface and cause slow or unstable response. Install the electrode in a representative, adequately mixed location and provide access for inspection and cleaning.

Unlike pH measurement, ORP does not have a universal automatic temperature-compensation calculation. An integrated temperature sensor can display process temperature or support a validated process-specific correction, but it does not automatically normalize every ORP reading to 25 °C.

The maximum 6 bar pressure rating should not be assumed at 130 °C. Confirm the pressure-temperature limits of the electrode, holder, seals, process fitting, and cable assembly.

Application

• Chemical Processing
• Industrial Wastewater Treatment
• Industrial Water Treatment
• Oxidation–Reduction Process Control
• Process Equipment Integration
• OEM Monitoring & Automation Systems