Seawater is a very challenging environment for chlorine sensors. Most cannot handled the corrosive environment and require waste streams, reagent feeds, membranes, electrolytes and frequent maintenance. HSI’s Total Residual Oxidant Sensor's breakthrough design is both simple, reliable and requires very little maintenance. HSI has developed a technology platform for measuring total oxidants (chlorine/bromine) that integrates four key measurement parameters, Amperometric Chlorine (or bromine in seawater), ORP, Temperature and Conductivity into a reliable, synergistic system.
This new TRO sensor is capable of reagentless operation in seawater for extended periods without calibration and has significant advantages over the Oxidation Reduction Potential (ORP) method. Amperometry is an electrochemical technique that measures the change in current resulting from chemical reactions taking place on the electrodes. The generated current is proportional to the TRO concentration. A typical amperometric sensor consists of three electrodes; an anode, cathode and a reference electrode. The 3-electrode bare electrode design generally makes the measurements more stable and provides longer life for the working and reference electrodes. There are no membranes to clog or replace.
- Measures 4 Water Parameters:
- Free Chlorine or Bromine (TRO), ORP, Conductivity, Temperature
- Rugged design solid-state sensor without gels or glass (no pH)
- No membranes to clog or replace
- No waste stream
- Resistant to biofouling
Most chlorine sensors suffer from “Sensory Deprivation.” Any sensor failure usually results in a false “no chlorine” signal, resulting in either a false alarm or an overfeed condition. Unlike other approaches, sequential measurement of conductivity and ORP using the same electrodes for chlorine improves reliability and reduces cost. This results in verification of the chlorine measurement using alternate measurement methods, and prevention of overfeed or false alarms. The conductivity measurement also detects the presence of air or a fault in the sensor wire connections that might result in a “zero chlorine” reading. Temperature and pH compensation of the chlorine signal is completely automatic.
Resistance to Biofouling
Wetted portions of the sensor that are subject to biofouling are manufactured from Teflon and are resistant to adhesion of organic gels and microorganisms. The hemispherical shape allows the release of large particulates in the flow path.
Flow Independent Measurement
The sensor contains an integrated magnetically coupled pump that generates a fixed flow across the sensor. This high velocity increases the sensitivity and accuracy of the sensor in addition to enabling operation in processes with flow velocities varying from 0 to 7 feet per second. The brushless pump motor life rating is 20,000 hours.
The sensor electrodes are self-cleaning. Teflon balls continuously clean the electrode surfaces enabling sensor operation is high hardness conditions.
Connect Directly to PLC
Direct connection of the sensor module (electronics and sensor) to a PLC ensures low cost simple operation (24VDC Input Power and RS485 Modbus Communications Interface).