Find the measurement behind your marine treatment system. Halogen helps shipowners, engineers and service teams measure total residual oxidant in seawater, select a marine sensor and identify an installed unit.
Shipowners · Fleet technical teams · Marine service partners · BWMS OEM manufacturers
4,500+ TRO sensors delivered for ballast water management systems worldwide.
DNV-GL · Korean Register (KR) · IECEx
Marine approvals are configuration-specific. Request the applicable certificates for your selected model.
Halogen Systems has manufactured sensors since 2013 near Reno, Nevada, with more than eleven patents worldwide. Explore the patents ↗
Riviera’s February 2021 feature reports on DNV GL type approval for Halogen’s direct-insertion TRO sensor and shares feedback from ballast water treatment engineers on installation simplicity, reliability and reagent-free operation.
Read Riviera: Low maintenance, lower-cost TRO sensor receives DNV GL type-approval ↗“BWMS designers should look closely at the Halogen TRO sensor.”
Riviera Expert Views · · Sponsored by Halogen Systems Inc. Refer to the applicable current certificate for your sensor configuration.
Reagent-free measurement takes one recurring supply requirement off the voyage plan. Direct pipe insertion takes the sample line out of the measurement path.
When a vessel is underway, replacing analyzer chemicals is not a quick trip to a supplier. Crews must plan inventory, storage and replenishment around voyages and port calls. Halogen’s TRO measurement needs no analytical reagents to stock, prepare or replace.
Biofilm and deposits in sampling tubing can consume residual oxidant on its way to an analyzer. The delivered sample may no longer represent the water in the ballast pipe. Measuring directly in the pipe avoids this external sample-line loss and transport delay.
Direct insertion removes the separate sample tubing, sample pump and analyzer drain from the installation. Reagent-free sensing also removes reagent-feed tubing and its associated blockage checks. The crew can focus on the sensor and its measurement point.
| Operator consideration | Reagent-based analyzer with a sample line | Halogen direct pipe insertion |
|---|---|---|
| Voyage supplies | Plan reagent stock, storage and replacement. | No analytical reagent inventory. |
| Sample integrity | Maintain tubing cleanliness and account for transport time. | Measures at the pipe; no external sample-line journey. |
| Service points | Maintain reagent delivery and sample-handling components. | No reagent-feed system or external sampling circuit. |
Comparison applies to Halogen direct-insertion installations; side-stream installations still require sample-path care. Reagent-free measurement does not eliminate BWMS treatment chemicals or routine sensor service. Read Halogen’s technical discussion of direct measurement and sample-line delay ↗
Review my TRO installationIn a full-flow electrochlorination system, locate the treatment measurement after electrolysis and adequate mixing. The TRO signal helps the control system follow oxidant production as ballast water enters the tanks.
Measure the water leaving the ballast tanks to inform neutralizing-agent dosing. Give the crew a clear view of the residual and the measurement status during discharge operations.
Check the residual after neutralization at the designated final monitoring point. Match the low-range performance and alarm settings to the approved system requirements.
Direct Pipe Insertion measures in the ballast line without a separate sample pump, sample tubing or analyzer waste line. Reagent-free and membrane-free TRO measurement means no analytical reagents to replenish.
SensiCLENE circulates polymer beads around the electrodes to remove salt and organic deposits. HiRes TRO maintains local flow at the sensing surfaces as pipe flow changes.
HaloSAL compensates using conductivity. DryGLAS pH and Rapid Response ORP technology address the dry periods that occur when ballast piping is emptied.
An impeller drives flow across the electrodes for direct pipe measurement as ballast-line flow changes from 0 to 4 m/s. The magnetically coupled pump motor has a published 20,000-hour life expectancy.
Circulating polymer beads continuously clean the electrodes. Salt and organic buildup are removed within minutes of startup. The marine design needs no sensor filters to clean and is designed for turbid water in muddy ports.
The pH cartridge tolerates dry-out and the positive and negative pressures encountered in ballast piping. It stabilizes within minutes after extended dry periods.
Conductivity-based automatic salinity compensation supports measurement from seawater to freshwater at 0.2 PSU salinity.
For systems using ORP, the sensor is designed to survive dry periods without dry-out damage or poisoning.
| Maintenance consideration | Halogen DPI | DPD reference in the brochure |
|---|---|---|
| Calibration / service interval | 6–12 months | 1 month |
| Time to measurement at PLC | 45 seconds | 180 seconds |
| Maintenance interval | 24 months | 1 month |
| Very turbid water | Listed as unaffected | Listed as affected |
Historical comparison from the supplied May 2021 brochure, not a specification for every current DPD analyzer. The measurement cycle is separately specified as 45–55 seconds. Direct pipe insertion also avoids a separate analyzer skid, sampling-circuit automatic valves, pressure regulators and Y-strainers.
For crews working around fouled pipework, the practical questions are access, cleaning and dependable measurements after a restart. Discuss those conditions early, whether the monitoring point is on a ship, tanker or offshore installation.
Marine fouling examples. These photographs show the application environment, not a sensor performance test or before-and-after treatment result.
Halogen publishes 6–12 months between calibration checks and a 24-month maintenance interval for this marine range. Plan service around the selected configuration and operating conditions. Marine technology details ↗
Build TRO monitoring into your own system, with your own operator interface and branding. Halogen’s reagent-free TRO sensor can communicate directly with your PLC over Modbus RTU without a separate Halogen controller, with integration development for your application.
Install the sensor directly in the ballast pipe using the appropriate flange or hot-tap configuration. Measure at the process point without external sample tubing or a separate analyzer skid.
Bring measurements into your control system through Modbus RTU. Develop the PLC interface for the selected sensor, including register mapping, measurement scaling, sensor status and fault handling.
Present TRO readings, trends and alarms through your own branded HMI. Keep the operator experience within your BWMS interface, and discuss OEM sensor labeling with Halogen as part of the integration review.
A flexible installation, with engineering built in. Direct PLC integration requires development and commissioning. Review the sensor’s electrical and communication requirements, implement your system’s control logic, and validate measurement and alarm behavior before putting the installation into service.
Compare all six configurations in the marine brochure, with non-hazardous and hazardous-area options for each installation type.
SWN-P+
Direct insertion into ballast piping through the specified pipe or flange connection.
Ask about this model ↗
SWN-P+CHM
Sensor with a measurement chamber for installations using a representative side stream.
Ask about this model ↗
SWN-P+HT2-HTV-01
Direct-insertion sensor with the matching hot-tap valve assembly.
Ask about this model ↗EX-P-STD2
EX measurement module for the specified flange or pipe installation.
Ask about this model ↗
EX-P-STD-CHM
EX sensor with a side-stream chamber. Confirm sample supply and installation requirements.
Ask about this model ↗
EX-P-HT4-HTV-1
EX sensor with a matching valve assembly for direct pipe insertion.
Ask about this model ↗Images illustrate the sensor configurations. Confirm the complete ordering code, mounting dimensions and applicable certification with Halogen.
Shown with a flange-mounted long insertion probe. Share your pipe dimensions, insertion requirements and seawater duty so Halogen can confirm the correct titanium configuration and ordering code.
| TRO measurement range | 0.03–20 ppm |
|---|---|
| TRO accuracy | ±15% or ±0.06 ppm, whichever is greater |
| ORP | −1,100 to +1,100 mV |
| Conductivity / salinity channel | 200–50,000 µS (published units) |
| pH | 5–12 |
| Temperature measurement | 0–100 °C |
| Measurement cycle | 45–55 seconds, depending on selected measurements |
| Digital communication | Modbus RTU |
| Mounting | Non-hazardous | Hazardous variant |
|---|---|---|
| Pipe / flange | SWN-P+ | EX-P-STD2 |
| Side-stream chamber | SWN-P+CHM | EX-P-STD-CHM |
| Hot-tap assembly | SWN-P+HT2-HTV-01 | EX-P-HT4-HTV-1 |
Published hazardous-area marking: Ex db ib IIC T5 Gb, Zone 1, Group IIC.
A separate Halogen controller is not required when the sensor is integrated into an OEM PLC with the necessary development. Optional non-hazardous D01 / D01-4 transmitters provide two / four 4–20 mA outputs, 24 VDC input and Modbus RTU.
Source: Halogen marine brochure, specification and model tables. Measurement ranges are not installation operating limits. Request the current model datasheet for pressure, wetted materials, temperature limits and certification scope. Confirm low-residual performance against your system’s discharge criterion.
The existing product page lists 0.03 ppm in its detection highlight and 0.0–0.25 ppm in the chlorine limit of detection (LOD) row. These are different statements. The measurement range shown here is 0.03–20 ppm; ask Halogen for the model-specific detection limit and low-residual validation before specifying a discharge-monitoring point.
Download the sensor model guide, measurement specifications, installation comparison and marine technology overview for your vessel or engineering team.
Brochure edition: May 2021. Contact Halogen for current configuration and ordering details.
Assembly animation · approximately 65 seconds. Use the applicable installation and service manual for removal procedures.
Download the removal video (MP4 · 5.6 MB) ↓A TRO sensor supplied with your ballast water treatment system may carry the system supplier’s label. If the measurement module or probe looks familiar, Halogen can help identify it.
For a replacement sensor, spare probe or service enquiry, send:
We’ll help match the sensor and mounting arrangement. Replacement selection also needs the system’s electrical, software and approval requirements.
Get help identifying my TRO sensorNo. An OEM can integrate the TRO sensor directly into its PLC using Modbus RTU, without a separate Halogen controller. This requires PLC integration development and commissioning for the selected sensor configuration, including measurement mapping, status handling and system control logic. Direct pipe insertion and direct PLC communication give the OEM flexibility in both mounting and control-system design.
Yes. OEM manufacturers can present Halogen TRO measurements through their own PLC and branded HMI rather than a separate Halogen controller. The OEM develops the interface, alarms and control logic within its own system. Discuss sensor labeling and the required integration configuration with Halogen during the design review.
A Total Residual Oxidant (TRO) sensor measures residual oxidant in treated ballast water. In an electrochlorination BWMS, that measurement supports treatment control, neutralization dosing and final discharge verification. Halogen provides reagent-free sensors for direct pipe insertion and side-stream installations.
The marine range reports chlorine (TRO), oxidation reduction potential (ORP), conductivity / salinity, temperature and pH where configured. The published TRO range is 0.03–20 ppm, with accuracy of ±15% or ±0.06 ppm, whichever is greater. Communication is Modbus RTU.
Reagent-based monitoring adds chemicals to the vessel’s stores, with storage conditions, usable life and replacement schedules to manage. Halogen measures TRO without analytical reagents, removing that resupply dependency from the measurement. Treatment and neutralization chemicals remain separate requirements of the BWMS.
Yes. Deposits and biofilm in a sample line can consume oxidant before the water reaches the analyzer, so the reading may understate the residual in the ballast pipe. Transport time also delays the reading. Direct pipe insertion removes that external sample-line path; the sensor still needs correct placement and routine verification.
Your system documentation may call it a TRO monitor, residual oxidant sensor or measurement module. Halogen sensors can be supplied under a system supplier’s label. Send the nameplate, serial number, photos of the probe and mounting assembly, and the BWMS make and model. We can help establish the sensor identity and the correct service route.
A photo starts the identification process. Before ordering, match the part number, insertion length, mounting, electrical interface, firmware requirements and area classification to the installed system. Similar housings do not establish interchangeability.
Typical monitoring duties include checking oxidant after electrolysis, measuring remaining residual during de-ballasting, and verifying neutralization before overboard discharge. Use the measurement points and acceptance criteria specified for your treatment system.
Yes. Share whether the duty is ballast treatment, a seawater intake or a cooling-water circuit, together with oxidant chemistry, expected residual and installation conditions. The team can review the appropriate sensor configuration for your vessel or facility.
No. Define the oxidant chemistry and the reporting basis for your process. A chlorine-based seawater treatment duty should not be treated as evidence of suitability for every other oxidizer. Ask for a review of the actual treatment chemistry.