Water Trap Membrane Filter Orientation for Capnometer Accuracy
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Solution Overview
Problem
Capnometers, especially diverting types, face interference and increased rise time due to water condensation in respiratory gases, leading to reduced system resolution and accuracy, particularly at low gas flow rates.
Innovation Solution
A water trap with a membrane filter disposed in a flat configuration parallel to the fluid flow within a tube, minimizing dead space and turbulence, and preventing water from entering the sensing chamber, thus maintaining laminar flow and reducing pressure drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a water trap is used to remove condensed water from respiratory gases, then water damage to the sensing chamber is prevented, but the rise time is lengthened and measurement accuracy is reduced
Solution Approach 1:
The patent positions the membrane filter in a planar configuration perpendicular to the tube axis, creating a flow path that passes through the filter surface area rather than through a traditional linear filter element. This dimensional arrangement minimizes the volume of the filter housing and reduces dead space, thereby maintaining faster response times while still providing effective water removal
Solution Approach 2:
The membrane filter is positioned specifically at the region where water condensation is most likely to occur (near the inlet), creating a localized water removal zone. This allows the majority of the tube length to maintain open, unobstructed flow, preserving overall flow characteristics and rise time while providing targeted water removal where needed
2Reliability
If traditional filtering methods are used to remove water, then water is trapped effectively, but dead space and turbulence increase
Solution Approach 1:
The patent employs a thin membrane filter that can be positioned flat within the tube, creating minimal obstruction to flow. The membrane's thin profile reduces the volume required for filtration, minimizing dead space while maintaining effective water removal through the membrane's porous structure
Solution Approach 2:
By arranging the filter membrane in a planar configuration across the flow path rather than using a traditional cylindrical filter element, the patent reduces the longitudinal space occupied by the filter assembly. This dimensional change minimizes dead space and reduces flow disruption, maintaining laminar flow characteristics while providing effective filtration
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
The solution achieves a low pressure drop and rapid T90 rise time, enhancing the accuracy and crispness of capnometer waveforms by maintaining laminar flow and minimizing interference, even at low gas flow rates.
Implementation Method 1
a membrane filter...configured to prevent the water from passing therethrough
Implementation Method 2
maintaining laminar flow and reducing pressure drop
Data Source
AI summary
Apparatus and methods are described, including a water trap (28) that includes an inlet portion (40), via which a mixture of gas and water is configured to enter the water trap, and an outlet portion (42), via which the gas is configured to exit the water trap, the inlet portion and the outlet portion being formed separately from one another and being coupled to one another, such as to form a tube (44) that defines a longitudinal axis and that defines an internal hollow volume through which the gas is configured to flow. A membrane filter (46) is disposed in a flat configuration within the tube, between the inlet portion and the outlet portion, such that the membrane filter is substantially parallel to the longitudinal axis of the tube, the membrane filter being configured to prevent the water from passing therethrough. Other applications are also described.