Dual Sensor Dissolved Oxygen Measurement with Light-Shielded Reference
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Solution Overview
Problem
Existing dissolved oxygen probes degrade over time, leading to inaccurate measurements and requiring frequent recalibration or replacement, especially in hazardous or inaccessible locations, resulting in resource wastage and safety risks.
Innovation Solution
A system using at least two dissolved oxygen sensors, where one sensor (trend sensor) continuously measures oxygen levels at a high frequency and another (reference sensor) measures intermittently at a lower frequency, with the reference sensor shielded from light to prevent degradation, allowing for periodic recalibration of the trend sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single dissolved oxygen probe is used for continuous monitoring, then measurement coverage is maintained, but the probe degrades over time leading to inaccurate measurements and requires frequent replacement
Solution Approach 1:
The system divides the measurement function into two separate probes: a trend probe that continuously monitors dissolved oxygen levels and a reference probe that periodically measures oxygen levels for calibration purposes. This segmentation allows each probe to have specialized functions, extending overall system reliability while reducing the degradation burden on any single probe.
Solution Approach 2:
The reference probe acts as an intermediary calibration source that periodically corrects the trend probe's measurements. By introducing this intermediate calibration mechanism, the system maintains accurate measurements over extended periods without requiring frequent replacement of the main monitoring probe.
2Reliability
If probes are placed in hazardous or inaccessible locations for monitoring, then measurement capability is provided, but maintenance and replacement become difficult and dangerous
Solution Approach 1:
The reference probe automatically performs calibration measurements and corrects the trend probe's data without requiring manual intervention. This self-service capability eliminates the need for personnel to access hazardous locations for routine calibration, significantly improving safety while maintaining measurement reliability.
Solution Approach 2:
The reference probe serves as an automated intermediary that handles the calibration function remotely, eliminating the need for human operators to physically access difficult-to-reach or hazardous locations for maintenance activities.
3Productivity
If a probe is continuously exposed to light for oxygen measurement, then measurement function is maintained, but the probe degrades faster requiring more frequent recalibration
Solution Approach 1:
The system segments the measurement duties between two probes with different operational patterns. The trend probe operates continuously at high frequency for real-time monitoring, while the reference probe operates periodically at lower frequency specifically for calibration. This segmentation allows the trend probe to maintain high productivity while the reference probe's periodic operation minimizes its exposure to degrading conditions.
Solution Approach 2:
The reference probe performs measurements periodically rather than continuously, which reduces its cumulative exposure to light and other degrading environmental factors. This periodic action extends the reference probe's stability while still providing sufficient calibration data to maintain trend probe accuracy.
Data Source
AI summary
An embodiment provides a method for measuring dissolved oxygen of an aqueous sample, including: introducing an aqueous sample into a measurement device comprising at least two dissolved oxygen sensors, wherein at least one of the at least two dissolved sensors comprises a trend sensor and at least another of the at least two dissolved sensors comprises a reference sensor; measuring a first value of dissolved oxygen using the trend sensor, wherein the trend sensor samples at a trend frequency; measuring a second value of dissolved oxygen from a reference sensor, wherein the reference sensor samples at a reference frequency, the reference frequency being less than the trend frequency; and correcting the first value of dissolved oxygen based upon the second value of dissolved oxygen. Other aspects are described and claimed.