Monitoring Water Quality with One Measuring Instrument

Reliable assessment of water quality often requires the measurement of several parameters. When these are determined individually using different measuring instruments, the effort required for measurements, documentation and evaluation increases.

The HORIBA U-51 (2 m) from the U-50 series enables mobile multi-parameter measurements using a combined sensor probe. Various water parameters can be recorded within a single measurement process and displayed directly on the control unit.

The instrument is particularly suitable for on-site investigations of surface waters, water quality monitoring and the inspection of water treatment processes.

The U-51 version is equipped with a 2-metre sensor cable and enables the simultaneous display of up to 10 measured and calculated values.

Measuring Parameters of the HORIBA U-51

The multi-parameter measuring instrument records important physical and chemical parameters for assessing water quality.

• pH value: Assessment of the acidic or alkaline characteristics of a water sample.
• Oxidation-Reduction Potential (ORP): Measurement of the electrochemical oxidation-reduction potential.
• Dissolved Oxygen (DO): Monitoring the oxygen content in water.
• Electrical Conductivity: Assessment of electrical conductivity as an indicator of dissolved ions.
• Salinity: Determination of salt content based on conductivity measurements.
• TDS: Determination of total dissolved solids as a calculated value.
• Seawater Specific Gravity: Calculated parameter for corresponding water samples.
• Temperature: Measurement of water temperature for the assessment and compensation of temperature-dependent parameters.

Depending on the parameter, different display formats and calculated values can be shown. The U-51 version does not feature turbidity measurement.

Functions and Features

The HORIBA U-51 combines a multifunctional sensor probe with a portable control unit. This allows several water parameters to be recorded within a single measurement process, without requiring a separate measuring instrument for each parameter.

Clear Measurement Display

The control unit features a backlit monochrome graphic display on which the recorded measurement values are clearly presented. This facilitates the assessment of water quality directly at the measuring location.

Data Storage and Transfer

The instrument offers a storage capacity of up to 10,000 data sets. Stored measurement data can be transferred via the USB interface for further documentation and evaluation.

Designed for Mobile Use

The robust construction and water-protected components are designed for measurements under demanding operating conditions. The sensor probe complies with protection class IP68, while the control unit complies with protection class IP67 when the sensor cable is connected.

Calibration and Sensor Maintenance

The integrated calibration functions support the preparation of the measuring instrument for reliable measurements. Regular calibration, cleaning and maintenance of the sensors in accordance with the manufacturer's instructions are necessary to ensure consistently meaningful results.

Typical Applications

The HORIBA U-51 is suitable for various tasks in water analysis and environmental monitoring.

• Surface Waters: Investigation of rivers, lakes and other natural water bodies.
• Environmental Monitoring: Measurement of important water parameters to observe changes in water quality.
• Industry and Process Water: Spot checks of relevant water parameters in industrial environments.
• Wastewater and Discharges: Supplementary on-site measurements to assess water characteristics.
• Research and Field Investigations: Mobile data collection for scientific and application-related investigations.

Advantages of Multi-Parameter Measurement

• Measurement of several water parameters using a combined sensor probe.
• Fewer instrument changes during extensive on-site measurements.
• Direct display of measurement values on the portable control unit.
• Storage and transfer of measurement data for documentation.
• Robust design for mobile water investigations.
• 2-metre sensor cable for flexible measurements on site.

Technical Information and Downloads

A detailed overview of the technical features, measuring ranges, resolutions and further specifications of the HORIBA U-51 can be found under the "Specifications" tab.

Additional information about the HORIBA U-50 series is available in the product brochure in the download section.

Note on Scope of Delivery: From November 2026, HORIBA products will be supplied without batteries. Existing stock may still include batteries. Batteries are no longer included with newly manufactured products and must be purchased separately if required.