HH6100 Fluorescence Dissolved Oxygen Sensor| DO Electrode High Resistance to Corrosion and Abrasion

The HH6100 is a digital optical dissolved oxygen sensor based on fluorescence-quenching technology. Unlike electrochemical dissolved oxygen electrodes, it does not consume oxygen at the sensing surface and does not require liquid electrolyte or transmitter polarization.

The optical sensing cap contains a luminescent material excited by the sensor’s internal light source. Dissolved oxygen changes the luminescence response, and the internal electronics use this change to calculate oxygen concentration and percent saturation.

Because the method does not consume oxygen, the HH6100 is less dependent on sample flow than membrane-based electrochemical sensors. The sensing surface must still remain in representative contact with the water and free from bubbles, deposits, biofilm, and other coatings.

The sensor measures dissolved oxygen from 0 to 50 mg/L and saturation from 0 to 500%. Integrated compensation supports salinity values from 0 to 50 ppt, covering freshwater, brackish-water, and many seawater applications. Temperature, salinity, and pressure conditions must be correctly accounted for when calculating concentration or percent saturation.

Signal processing and communication electronics are integrated into the sensor body. The HH6100 operates from a 12–36 VDC supply and connects directly to compatible controllers, PLCs, gateways, and data loggers using Modbus RTU over RS485.

The sensor has a POM housing, ABS+PC optical cap, 3/4-inch NPT process connection, integrated cable, and IP68-rated construction. Its optical cap is replaceable when its response no longer meets the application requirements.

Key benefits

• Optical measurement technology: Requires no electrolyte replacement and no polarization period.
• Reduced flow dependence: Does not consume oxygen at the sensing surface.
• Integrated digital electronics: Measurement, compensation, and Modbus communication are handled inside the sensor.
• Freshwater and saline-water use: Supports salinity compensation from 0 to 50 ppt.
• Wide measurement coverage: Measures up to 50 mg/L and 500% saturation.
• Direct system integration: Connects to compatible automation platforms using RS485.
• Replaceable sensing cap: Optical cap can be renewed without replacing the complete sensor body.

Configuration options

• Extended cable: Cable lengths up to 100 metres, subject to DC voltage drop and RS485 network design.
• Process installation: Compatible immersion, pipeline, and flow-through assemblies can be selected for the application.
• Communication configuration: Device address, baud rate, parity, register map, and byte order should be matched to the receiving system.
• Replacement optical cap: Cap type, identification, calibration-data handling, and replacement procedure should be confirmed when ordering.

Measurement and maintenance notes

“Optical” does not mean maintenance-free. Inspect and clean the sensing cap at an interval appropriate to the process. Biofilm, sludge, scale, oil, algae, and trapped bubbles can isolate the optical surface from the sample and cause biased or slow readings.

Clean the cap only with methods compatible with the optical coating and cap material. Abrasive tools, aggressive solvents, and inappropriate chemicals may scratch, swell, cloud, or remove the sensing layer.

The claim of one year without calibration should be treated as an expected verification interval only under defined conditions. Critical applications should use periodic checks based on process risk, observed drift, cleaning frequency, and the site’s quality procedures.

Salinity compensation requires the correct salinity value. If the actual salinity changes but the configured value remains fixed, the reported dissolved oxygen concentration can be incorrect.

Percent saturation also depends on temperature and pressure. Confirm whether the sensor incorporates atmospheric-pressure or process-pressure compensation, or whether pressure data must be supplied externally.

For long RS485 networks, use appropriate twisted-pair cabling, daisy-chain topology, correct polarity, unique addresses, and suitable termination and biasing.

Classification

Product Type

• Industrial Sensors

Parameter

• Dissolved Oxygen
• Oxygen Saturation
• Temperature

Connectivity

• Digital
• RS485
• Modbus RTU

Application

• Municipal Wastewater Treatment
• Domestic Sewage Treatment
• Industrial Wastewater Treatment
• Aquaculture
• Seawater & Brackish Water
• Surface & Natural Water Monitoring
• Municipal Water Systems
• Biological Treatment & Aeration Control
• Remote Water-Quality Monitoring
• OEM Monitoring & Automation Systems