Amperometric Electrode Calibration via Water Loop
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Solution Overview
Problem
Existing amperometric measuring electrodes for disinfectant concentration in water face challenges in calibration due to unstable standard solutions, fluctuating disinfectant concentrations, and lack of constant flow conditions, particularly in small water supply systems, leading to unreliable measurements.
Innovation Solution
A method involving diverting water from a pipe to create a circuit for the amperometric measuring electrode, determining the disinfectant concentration using a discontinuous method like the DPD method, and using this concentration as a standard for calibration, ensuring precise calibration even with fluctuating concentrations and irregular flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard solutions with fixed concentrations are used for calibration, then calibration precision should improve, but the solutions are unstable in storage and difficult to obtain, leading to unreliable calibration standards
Solution Approach 1:
The system uses the actual water supply itself to generate calibration standards through the DPD method, rather than relying on external standard solutions. The water being monitored serves its own calibration purpose, eliminating the need for unstable standard solutions while maintaining calibration precision.
Solution Approach 2:
The DPD method acts as an intermediary to determine the disinfectant concentration in the water supply. Instead of directly using unstable standard solutions, the DPD chemical reaction provides a stable reference point for calibration by measuring the actual disinfectant level in the water.
2Productivity
If amperometric measuring electrodes are used for continuous monitoring, then productivity improves, but the electrodes require constant flow conditions to provide reliable measured values, which is difficult to achieve in small water supply systems with irregular water withdrawal
Solution Approach 1:
The system dynamically adapts to variable flow conditions by using the DPD method to determine actual disinfectant concentrations at different flow rates. This allows the calibration to account for flow variations, maintaining measurement reliability even when constant flow conditions cannot be achieved in small water supply systems.
3Ease of operation
If calibration is performed using disinfectant-containing water from the water supply, then ease of operation improves, but the pulsed addition of concentrated disinfectant changes the concentration at the measuring electrode, introducing calibration errors
Solution Approach 1:
The system performs preliminary determination of the disinfectant concentration using the DPD method before using this value for calibration. This preliminary action allows the system to account for concentration variations and establish an accurate calibration reference point, improving calibration accuracy while maintaining operational simplicity.
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 approach allows for reliable calibration of amperometric measuring electrodes, reducing errors and ensuring accurate disinfectant concentration monitoring in small water supply systems with fluctuating disinfectant levels and irregular water withdrawals.
Implementation Method 1
amperometric measuring electrode for determining a disinfectant content of water
Implementation Method 2
The DPD reagent N, N-Diethyl- p-phenylenediamine reacts with free chlorine to form a reddish color, the intensity of which is proportional to the concentration of free chlorine and can be measured photometrically
Data Source
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AI summary
The invention relates to a method for calibrating an amperometric measuring electrode (5) used to determine the concentration of disinfectants in water, wherein (a) the water to be tested is diverted from a water line (1) and passed by the amperometric measuring electrode (5) in a closed loop, (b) a measurement value of the amperometric measuring electrode (5) is determined, (c) the concentration of the disinfectants in the diverted water is determined, and (d) the concentration of the disinfectants determined in step (c) is used as a standard for calibrating the amperometric measuring electrode. Furthermore, an apparatus for carrying out this method and the use of the apparatus for calibrating an amperometric measuring electrode are described.