Monolithic PFA Coriolis Flowmeter Vibration Stability
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Solution Overview
Problem
Traditional Coriolis flowmeters using metal tubes face issues with adhesive degradation and differential thermal expansion, while plastic alternatives face challenges in manufacturing accuracy and temperature compensation, especially when using low-melting point fusible metal alloys that can contaminate the flow passageways.
Innovation Solution
A Coriolis flowmeter fabricated from elastic polymeric material with flow-sensitive elements integrally connected to a mounting base of the same material, avoiding mechanical joints and adhesives, and using CNC machining or injection molding with secondary drilling to form flow passageways, allowing for accurate temperature compensation of the spring constant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a PFA tube is attached to a metal base using cyanoacrylate adhesive, then the flowmeter can be fabricated, but the adhesive joint degrades over time from continuous vibration causing cracks and compromising device performance
Solution Approach 1:
The patent removes the adhesive joint from the design by fabricating the flow tube and mounting base as a single integrated PFA component. This eliminates the cyanoacrylate adhesive that degrades under vibration, directly resolving the reliability issue while maintaining ease of manufacture through injection molding or extrusion processes.
Solution Approach 2:
The flow tube and mounting base are merged into a single monolithic structure fabricated from one piece of PFA material. This integration eliminates the interface between dissimilar materials (metal base and plastic tube), removing the source of differential thermal expansion and adhesive degradation, thereby improving reliability without complicating manufacturing.
2Object-affected harmful factors
If PFA tubing is used instead of metal, then corrosion resistance is improved, but the tubing has inherent bends and curvature requiring complex annealing and etching processes to straighten
Solution Approach 1:
The patent eliminates the need for annealing and etching processes by using a monolithic PFA structure fabricated through injection molding or extrusion. These processes inherently produce straight, bend-free tubing without requiring post-processing to straighten curves, thereby reducing device complexity while maintaining corrosion resistance.
Solution Approach 2:
The desired straight geometry is achieved during the primary fabrication process (injection molding or extrusion) rather than requiring subsequent annealing. The manufacturing process itself creates the final straight shape, eliminating the need for separate corrective processes and simplifying the overall device fabrication.
3Ease of manufacture
If low-melting point fusible metal alloys are used for injection molding, then the flowmeter can be formed, but the alloy contaminates the flow passageways
Solution Approach 1:
The patent removes the low-melting point fusible metal alloy from the fabrication process entirely. Instead, it uses PFA material that can be molded at temperatures below 350°C without requiring fusible alloys. This eliminates the contamination source while maintaining ease of manufacture through standard injection molding or extrusion processes.
Solution Approach 2:
The patent replaces the problematic fusible metal alloy with PFA material that does not require such alloys for molding. The PFA can be processed at lower temperatures and does not leave contaminating residues, providing a cleaner, more reliable flow passageway while maintaining manufacturability.
4Strength
If metal flow tubes are used, then structural strength is maintained, but adhesive degradation and differential thermal expansion compromise the stability of the boundary condition
Solution Approach 1:
The patent merges the flow tube and mounting base into a single PFA component, eliminating the interface between dissimilar materials. This integration ensures uniform thermal expansion characteristics throughout the structure and removes the adhesive joint that degrades under vibration, thereby maintaining stable boundary conditions while preserving structural strength through the monolithic design.
Solution Approach 2:
The patent uses homogeneous PFA material for both the flow tube and mounting base, ensuring uniform thermal expansion properties throughout the structure. This homogeneity eliminates differential thermal expansion stresses and maintains consistent boundary conditions, improving reliability while maintaining adequate structural strength through the integrated design.
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 provides a stable and accurate Coriolis flowmeter with improved reliability and reduced contamination risks, enabling accurate mass flow rate measurement across a range of operating temperatures without the need for complex annealing or etching processes.
Implementation Method 1
Coriolis mass flowmeters can be used to measure the mass flow rate (as well as other properties) of a fluid flowing through a pipeline. Traditional Coriolis flowmeters employ various configurations of one or two tubes that are oscillated in a controlled manner allowing measurement of Coriolis induced deflections
Implementation Method 2
A Coriolis flowmeter fabricated from elastic polymeric material with flow-sensitive elements integrally connected to a mounting base
Data Source
AI summary
A subassembly of a Coriolis flowmeter is fabricated from a single monolithic piece of elastic polymeric material. The subassembly includes two flow-sensitive members and a base integrally connected to the two flow-sensitive members. The two flow-sensitive members include straight sections, and are substantially similar and parallel to each other. Flow passages are drilled along the straight sections of the two flow-sensitive members, and drilled entrances are sealed using the elastic polymeric material. A temperature sensor is fixedly attached to a flow-sensitive member for measuring a temperature of the flow-sensitive member and communicating the temperature to a metering electronics. The metering electronics determines a calibrated flow rate of fluid flowing through the Coriolis flowmeter that accounts for the temperature.