ORP Sensor

with HydroACT Multiparameter Analyzer

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The HydroACT range of online analyzers utilize the very latest and best ORP sensors available in the world today for measuring the online
Redox potential of any aqueous solution. They are platinum based sensors with integral reference electrodes which use no reagents,
are extremely stable, and have reduced maintenance and reduced whole life costs.

  • Up to 3 years continuous operation
  • Stable and reliable – excellent process control
  • Suitable for all potable and process waters
  • Suitable for very low conductivity waters
  • Suitable for use in Autoflush

The ORP sensors and flow cells are available with different controllers giving you the same great performance with different communication, display, and control options. With the HydroACT range of redox controllers, you get everything that you need and nothing that you don’t.

  • Remote Sites
  • Cooling Towers
  • Food Preparation
  • Paper Mills

Anywhere you have a requirement to measure ORP is a suitable application for the ORP sensor. The HydroACT ORP sensor range is particularly suited to working in sites where reliability and ease of use are most important.

Description

At the heart of the HydroACT range of ORP sensors are the ORP electrodes. These electrodes are filled with a polymeric gel. This innovative design make the electrodes more responsive and with a longer life than ordinary electrodes (up to 3 years).

ORP operates by measuring the potential between 2 electrodes. The potential tells operators the tendency of the water to oxidize (or reduce) pollutants. Tendency can be seen as a useful measure of the rate of oxidation.

Despite all of the additional functionality that this unit has to offer, the purchase costs are less than or comparable to, its competitors!

ORP is a ’Refex’ patented sensor which has a solid reference junction making it particularly resistant to poisoning and drift. The ORP4 Refex sensor is suitable for a range of chemical applications that normally mean replacing a standard ORP sensor very frequently.

Autoflush
The HydroACT unit with ORP sensor can come equipped to automatically clean itself at user defined intervals. The Autoflush is particularly useful in food preparation, pulp and paper, and many applications where there is likely to be a build up of solids in the sample. Autoflush is available for at line, and in line versions including dip and screw in autoclean piper versions.

Multi-Sensor Systems
The HydroACT range of online anaylzers can be fitted with additional sensors such as chlorine or pH. Please contact Chemtrac or a local representative for more details.


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The HydroACT ORP Sensor measures the online oxidation-reduction potential (Redox/ORP) of any aqueous solution, indicating the tendency of the water to oxidize or reduce pollutants.

ORP is measured by determining the electrical potential between two electrodes, and this potential reflects how strongly the water will promote oxidation or reduction reactions, which is a useful indicator of disinfection and process conditions.

The electrodes are filled with a polymeric gel and use a solid-state, non-porous Ag/AgCl reference, which improves responsiveness, extends life (up to about 3 years), and resists poisoning and drift compared to traditional porous junction designs.

The sensor covers a range from -1999 mV to 1999 mV, with a typical slope of 95–102%, long-term drift of less than 0.1 mV per hour, and reproducibility better than 0.1 mV.

ORP1, ORP2, and ORP3 are rated for 32–176 °F (0–80 °C), while ORP4 is rated up to 212 °F (100 °C), with a pressure range from 0 to 145 psi (0–10 bar).

ORP1 is suited for pools and spas, ORP2 for potable and process water, ORP3 for wastewater (with autoclean options), and ORP4 for demanding chemical applications requiring very long life and extreme chemical resistance.

The platinum-based ORP sensors use no reagents, include automatic temperature compensation, and are designed for reduced maintenance and lower whole-life cost, with an estimated sensor life of about 36 months depending on the application.

The ORP Sensor can be installed in auxiliary flow cells, at-line tees, handrails, welding stubs, and immersion assemblies, and can be supplied with Autoflush/self-cleaning options that automatically clean the sensor at user-defined intervals.

Specifications

ORP Sensor Specifications

Description
Type Platinum Band
Reference Type Solid state, non porous<br />
Ag/Ag Cl
ORP Range -1999 to 1999mV
Slope 95-102%
Pressure Range 0 - 145 psi (0 - 10 bar)
Long Term Stability (drift) < 0.1 mV/hour
Reproducibility < 0.1 mV
Response Time 95% of step < 5 sec
Temperature Range 32° - 176° F (ORP1, 2, & 3)<br />
32° - 212° F (ORP4)
Wetted Surface PVDF/Glass/Pt ring/Viton 0 rings
Cable Low noise Coaxial + 4 wires<br />
Cable length - 19.7 ft. (6 m)<br />
Up to 32.8 ft. (10 m)
Shelf Life 12 months
Temperature Compensation Automatically by integrated<br />
thermistor PT100 (ATC)
Estimated Life 36 months (application dependent)

HydroACT Specifications

HA2 HA4 HA8
Sensor limit* 2 4 8
Analog output limit* 2 4 8
Relay limit* 4 8 16
Digital Input limit* 4 8 16
Isolated universal I/O
Nema 4X/IP65
Wall & panel mount
Multilingual
High resolution display
Graphical trending
On/Off threshold control optional optional optional
Advanced control (e.g. PID) optional optional optional
Color display
Customizable data logs
MicroSD card download
Remote (Internet) access optional optional
PROFIBUS, Modbus optional optional

Downloads

Title Category Upload Date File Size Download
PDF ORP Sensor Datasheet
Corrosion and Scaling, ORP Sensor Jun 10, 2026 240 KB Download
PDF pH Sensor Datasheet
Corrosion and Scaling, pH Jun 10, 2026 160 KB Download
PDF

ORP Sensor Datasheet

240 KB
Corrosion and Scaling, ORP Sensor
June 10, 2026
PDF

pH Sensor Datasheet

160 KB
Corrosion and Scaling, pH
June 10, 2026