ABB Residual chlorine monitor AW402 with PID
Overview
The ABB AW402 Residual Chlorine Monitor with PID is a continuous, online instrument from ABB’s AW400 series that measures free or total residual chlorine, chlorine dioxide, or ozone using a reagentless amperometric sensing cell, with an integrated PID controller built in for direct feedforward dosing control. Unlike the colorimetric Aztec 600 family of ABB analyzers, the AW400 series uses a concentric gold-and-copper electrode cell that generates a current signal directly proportional to oxidant concentration – a design that eliminates ongoing reagent consumption entirely at pH 7.5 and below, a meaningful running-cost advantage for continuous disinfection monitoring.
With fast quotation turnaround and technical support, Seven Star LLC proudly supplies the AW402 Residual Chlorine Monitor to municipal water authorities and industrial disinfection system operators across the Sultanate of Oman and the wider Gulf region. Every unit is supplied on request with manufacturer documentation, regional technical support, and access to original ABB spare parts – with lead time and availability confirmed at quotation.
Measurement Principle
The AW402 uses an amperometric cell with a gold inner (measuring) electrode and a copper outer electrode: when oxidizing substances such as chlorine, chlorine dioxide, ozone, or their derivatives are present in the sample between the electrodes, the gold measuring electrode is depolarized, generating a current signal directly proportional to oxidant concentration. A PT100 thermistor provides software-based temperature compensation, and the sensor covers a 0 to 20 ppm range across chlorine, chlorine dioxide, and ozone detection with a minimum detection limit of 0.005 ppm.
In practical terms this delivers accuracy of 2% or ±0.01 ppb in unbuffered waters below pH 7.5, and 2% or ±10 ppb in buffered waters up to pH 10, with a response time reaching 90% of a step change within 90 seconds – fast enough to support real-time dosing control rather than just passive monitoring. Because the cell operates reagentlessly at pH 7.5 or below, the AW402 avoids the ongoing chemical cost and reagent logistics that a colorimetric chlorine analyzer would require for continuous operation.
Engineering Design of the ABB AW402
What sets the AW402 apart within the AW400 series is its integrated PID controller: rather than pairing the analyzer with a separate loop controller to drive a chlorine dosing pump, the AW402 closes the control loop itself, supporting feedforward dosing strategies that adjust chemical feed rate directly from the measured residual, without the expense of a standalone controller. The sensor assembly is self-cleaning, using a vortex of corundum sand circulating around the electrodes to keep them free of biofilm and scale buildup that would otherwise degrade sensor response over time.
The instrument supports up to three sensor inputs, allowing chlorine, pH, and ORP measurements to be combined on a single transmitter where a plant needs multi-parameter disinfection monitoring from one panel. Pressure-regulated sample flow means the sensor assembly does not require additional flow-control plumbing on installation, and the combination of reagentless operation and self-cleaning electrodes gives the AW402 up to 60 days of unsupervised operation between routine service visits.
Key Features
The AW402 combines reagentless amperometric measurement with built-in dosing control, including:
- Reagentless amperometric measurement of free or total chlorine, chlorine dioxide, or ozone at pH 7.5 or below.
- Integrated PID controller for direct feedforward dosing control, eliminating the cost of a separate loop controller.
- Measuring range of 0 to 20 ppm with a minimum detection limit of 0.005 ppm and 90-second response time.
- Self-cleaning sensor assembly using corundum sand vortex circulation to prevent electrode fouling.
- Support for up to three sensor inputs, combining chlorine, pH, and ORP on a single transmitter.
- Pressure-regulated sample flow with no additional plumbing required for installation.
- Up to 60 days of unsupervised operation between service visits.
- PT100-based software temperature compensation for stable readings across varying sample temperatures.
Industrial Applications
Continuous, reliable disinfection monitoring is a core requirement across Oman and the GCC’s drinking water, wastewater, and pool/spa facilities, and the AW402’s built-in PID control makes it particularly well suited to plants that want dosing control and monitoring from a single instrument. In municipal drinking water treatment, the AW402 monitors and controls residual chlorine directly at the point of disinfection, ensuring the finished water leaves the plant with adequate residual to maintain disinfection through the distribution network without manual dosing adjustment. In cooling systems, tertiary wastewater treatment, and fruit and vegetable disinfection processes, the same reagentless measurement and feedforward control capability keeps oxidant dosing tracking process demand automatically.
With engineering support in Muscat, Seven Star LLC supplies the AW402 Residual Chlorine Monitor to water utilities, industrial disinfection operators, and food and beverage processors across Muscat, Sohar, and Salalah, as well as the wider Gulf region. The instrument is not recommended for meat processing, high oil/fat, or fibrous sediment applications, where the sensor’s pressure-regulated flow assembly is unsuited to the sample matrix – Seven Star LLC’s instrumentation division can advise on the correct AW400 series variant for these applications.
Technical Specifications
Key technical specifications for the ABB AW402 Residual Chlorine Monitor are summarized below.
| Parameter | Specification |
|---|---|
| Model | ABB AW402 Residual Chlorine Monitor with PID |
| Measuring Principle | Amperometric, gold/copper concentric electrode cell (reagentless at pH ≤7.5) |
| Measuring Range | 0 to 20 ppm (chlorine, chlorine dioxide, ozone) |
| Minimum Detection Limit | 0.005 ppm |
| Accuracy | 2% or ±0.01 ppb (pH <7.5); 2% or ±10 ppb (pH <10) |
| Response Time | 90% step change within 90 seconds |
| Control | Integrated PID controller for feedforward dosing |
| Sensor Inputs | Up to 3 (chlorine, pH, ORP combinations) |
| Unsupervised Operation | Up to 60 days |
| Temperature Compensation | PT100 thermistor, software-based |
Request a Quote for ABB Residual chlorine monitor AW402 with PID
Seven Star LLC welcomes formal RFQs for the ABB AW402 Residual Chlorine Monitor from municipal water utilities, industrial disinfection operators, and food and beverage processors across Oman and the GCC. We supply on request with lead time confirmed at quotation, provide the full technical datasheet on request, and can connect your team directly with our instrumentation division for application sizing and technical support. Contact Seven Star LLC today to request a formal quotation or technical consultation for your chlorine monitoring and dosing control requirements.
Related Products
- Datasheet ABB-Residual chlorine monitor Datasheet Download
Reviews
There are no reviews yet.