Dissolved Oxygen Meter Calibration via In-Situ Air Saturation
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Solution Overview
Problem
Existing dissolved oxygen meter calibration methods are inaccurate due to variations in air oxygen concentration caused by changes in water vapor partial pressure and are difficult to perform at certain measurement sites, requiring the meter to be removed from the sample solution.
Innovation Solution
A dissolved oxygen measurement system with a mode switching mechanism that allows for calibration without removing the meter from the sample solution by saturating air with water vapor within the measurement cell, using a feed port below the sample solution surface and a discharge port above the cell's internal bottom, ensuring constant oxygen concentration for accurate calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the dissolved oxygen meter is lifted out of the sample solution for calibration, then the calibration process is simple and easy to conduct, but the reference value varies due to changes in water vapor partial pressure and measurement accuracy deteriorates
Solution Approach 1:
The patent introduces air as an intermediary medium to transfer the calibration function from the external environment to the internal cell environment. By feeding air into the cell through the feed port, the calibration can be performed with the meter remaining in the cell, eliminating the need to lift it out while maintaining a stable reference value through controlled air saturation with water vapor.
Solution Approach 2:
The patent changes the physical state of air by saturating it with water vapor through contact with the sample solution. This parameter change ensures that the partial pressure of water vapor becomes constant, thereby stabilizing the oxygen concentration reference value during calibration and improving measurement accuracy.
2Ease of operation
If the dissolved oxygen meter is lifted out of the sample solution for calibration, then the calibration can be performed, but it becomes difficult to conduct calibration at measurement sites where the meter cannot be removed
Solution Approach 1:
The patent makes the cell multi-functional by enabling it to serve both as a measurement chamber and as a calibration chamber. The feed port and discharge port allow the cell to perform calibration operations in-situ, making the system adaptable to various measurement sites where the meter cannot be removed from the sample solution.
Solution Approach 2:
The patent uses air as an intermediary to enable calibration without removing the meter. By feeding air into the cell and allowing it to become saturated with water vapor, the system creates a stable calibration environment within the cell, making calibration accessible at any measurement site regardless of whether the meter can be lifted out.
3Ease of operation
If air is fed into the cell for calibration without water vapor saturation, then the calibration process is simple, but the oxygen concentration reference value changes and calibration accuracy deteriorates
Solution Approach 1:
The patent performs preliminary action by saturating the air with water vapor before using it for calibration. The air is fed into the cell first, allowed to contact the sample solution to become saturated, and only then is the calibration performed. This preliminary saturation ensures constant water vapor partial pressure and accurate calibration results.
Solution Approach 2:
The patent changes the humidity parameter of the air by saturating it with water vapor through contact with the sample solution. This parameter change ensures that the partial pressure of water vapor becomes constant during calibration, thereby maintaining a stable oxygen concentration reference value and improving calibration accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method improves measurement accuracy by maintaining constant oxygen concentration during calibration, simplifies the calibration process, and allows for zero-point calibration without removing the meter, ensuring ease of operation and reduced measurement errors.
Implementation Method 1
part of the sample solution remains in the cell during the calibration. Therefore, the air fed into the cell is brought to a state in which it is saturated with water vapor
Data Source
AI summary
In order to improve measurement accuracy by accurately calibrating sensitivity of a dissolved oxygen meter without impairing easiness in calibration, the present invention includes a dissolved oxygen measuring device that includes a cell to be loaded with a sample solution, and a dissolved oxygen meter that is attached to the cell and measures an oxygen concentration in the sample solution; and a mode switching mechanism to switch between a measurement mode, in which a sensor surface of the dissolved oxygen meter is substantially in contact with the sample solution in the cell, and a calibration mode, in which the sensor surface is substantially not in contact with the sample solution in the cell, by feeding air into the cell through a feed port disposed on the cell, and by discharging part of the sample solution through a discharge port disposed on the cell.