New Sensor Ideal for Ultrapure Water Applications

The Orbisphere 1100 series optical dissolved oxygen sensor from Hach Lange (UK) is providing major advantages to international service company Serco, in the course of its work to solve corrosion problems within the UK power generation sector. The instrumentation has helped reduce maintenance time and service requirements to improve the overall monitoring efficiency of testing carried out under plant conditions.

The sensor is used to monitor feedwater for the determination of dissolved oxygen levels in ultra pure water, in this instance, primary coolant in pressurised water reactors. Dissolved oxygen is vitally important in applications ranging from power generation, wastewater, drinking water and beverage production to monitor and control corrosion rates of materials.

Employing luminescent measurement technology, with no membranes or electrolyte, the solid state sensor head of the Orbisphere 1100 is unaffected by process changes or pressure shocks and requires minimal user intervention. It is quick and easy to calibrate, saving on maintenance costs as a result. Annual maintenance is limited to just a few minutes for a zero point calibration. In addition, chemicals are not required for this process, making the task easier and safer without reducing measurement precision. A further useful feature of the luminescent measurement technology is the elimination of effects on readings by other dissolved gases such as carbon dioxide and hydrogen.

The Serco Technical and Assurance Services laboratory team provides a dedicated service to industry, solving corrosion related plant problems. Its research laboratories enable the simulation of most plant conditions found within the power generation market. The majority of the work performed is for regulatory purposes and for plant lifetime/safety studies, so it is vitally important that fast, accurate and reliable results are produced during corrosion experiments that replicate plant conditions.

In order to tailor analytical services to customer needs, the laboratories employ a sophisticated range of the latest laboratory instruments.

Chris Auener, Structural Integrity Analyst at Serco, said: “The sub 10ppb accuracy of the system within the calibration range of the Orbisphere 1100 from Hach Lange reduces the inaccuracy of the measurement allowing

previously unseen readings within primary water conditions at Serco.

“We have numerous requirements from industry to recreate plant conditions with high purity water containing high concentrations of other dissolved gases and pH raisers and so the Orbisphere 1100 has proved ideal for our purposes. The instrument is also extremely userfriendly and meets the industry standard.”

Another benefit of the Orbisphere 1100 is that the sensor will fit into any existing Orbisphere sensor housings, allowing quick and reliable monitoring, even at sub 5ppb levels making the instrument ideal for all power

applications. The sensor is then connected to the Orbisphere 510 - Multi Channel O2, O3, CO2, N2 and H2 Gas Analyser and Orbisphere 410 - Oxygen and Ozone Gas Analyser.