Rosemount 490A optical dissolved oxygen sensor

Emerson has released the Rosemount 490A Optical Dissolved Oxygen Sensor, a digital Modbus-enabled measurement device designed to improve operational flexibility, simplify installation and reduce maintenance costs across many industrial applications in the water/wastewater treatment, biopharmaceutical manufacturing, food and beverage processing, and steam power generation industries.

Most dissolved oxygen probes for industrial applications are made for installation in specific and relatively benign conditions. These sensors are often only capable of communicating process values via analog signals to control systems, and they require frequent calibration to maintain accuracy and avoid sensor drift. To address these issues, the sensor provides suitable dissolved oxygen measurements in demanding environments, while simplifying integration into existing control systems with digital and universal Modbus RTU communication via an accompanying transmitter.

In addition to producing readings within 90 seconds of transition from dry to wet conditions, the sensor is capable of measuring process media in both liquid and gas phases, without requiring separate calibrations.

The sensor employs Environmental Protection Agency-approved luminescence-quenching technology, reducing the need for electrolyte refills to reduce maintenance requirements compared to traditional amperometric sensors. Its two-year sensing cap lifespan further minimises downtime and associated costs, and it can be calibrated in free air.

Additionally, the chemically resistant IP68-rated design enables reliable performance in challenging environments. Its small form factor, coupled with forward and rear facing 1-inch NPT threaded connections, simplifies installation in a variety of settings.

Unlike amperometric sensors, the 490A uses an optical sensor, which does not consume oxygen or require water flow for accurate measurements. Furthermore, guard cap options provide weighted orientation, anti-fouling protection, and air blast cleaning, catering to a wide breadth of applications.

The sensor is accurate to ±0.1 milligram per litre (0 to 20 mg/L) and ±2% (20 to 60 mg/L), enabling precise monitoring and control of dissolved oxygen levels.

It pairs with the Rosemount 1058 digital transmitter, which provides a diverse range of measurement signals for compatibility with numerous host control systems.