Gas Sensor Calibration Using Dual Flow Rates for Residual Gas Offset
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Solution Overview
Problem
Existing gas sensors used in breathing gas mixtures, particularly in anesthesia systems, face challenges in achieving accurate measurements due to residual anesthetic gases adhering to materials in supply lines, which cannot be fully removed in short flushing times, leading to measurement inaccuracies during brief interruptions.
Innovation Solution
A process involving two distinct flow rates of a test gas through the gas sensor, allowing for zeroing and calibration during continuous measurement by determining a parameter set that corrects for residual gas interference, using a formula to calculate an offset based on sensor responses at different flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a purge gas is used to flush the sensor and supply lines for a predetermined period to remove residual sample gas, then measurement accuracy is improved, but measurement operation is interrupted for a significant period of time
Solution Approach 1:
The patent changes the flow rate parameter of the purge gas from a single constant value to multiple varying values. By alternating between a first flow rate and a second flow rate during the flushing process, the system achieves more effective removal of residual sample gas from the supply lines while reducing the total flushing time required, thus maintaining measurement accuracy with shorter interruptions.
2Measurement precision
If a long flushing time is used to remove residual anesthetic gases from supply lines, then zeroing accuracy is improved, but continuous monitoring capability is lost
Solution Approach 1:
The patent implements periodic action by alternating between different flow rates during the flushing process. This periodic variation in flow rate creates enhanced mixing and removal effects that accelerate the clearance of residual anesthetic gases from the supply lines, enabling accurate zeroing to be achieved in a shorter time period, thereby preserving continuous monitoring capability.
3Productivity
If the purge gas flows through the sensor and supply lines for a short period, then measurement operation continuity is maintained, but residual anesthetic gases remain in the materials and affect zeroing results
Solution Approach 1:
The patent applies parameter changes by varying the flow rate of the purge gas during the flushing process. This variation in flow rate parameter enhances the removal efficiency of residual anesthetic gases from the supply line materials, achieving adequate zeroing accuracy even with shorter flushing times, thus maintaining measurement operation continuity.
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
Enables accurate gas concentration measurements without significant interruption, ensuring precise and continuous monitoring of breathing gas mixtures by correcting for residual gas effects using a parameter set derived from sensor responses at varying flow rates.
Implementation Method 1
a gas sensor to be tested is configured to determine the concentration of at least one gas component in a breathing gas mixture
Implementation Method 2
the first step is to ensure that no quantities of sample gas are present in or on the sensor; this is usually achieved by purging (flushing) for a certain period of time with a purge gas
Data Source
AI summary
A process (100) and system perform an adjustment/calibration on a gas sensor (60). The process makes it possible to correctly determine an offset (73) of the gas sensor (60) even with an unknown and non-zero interference gas concentration.