Diaphragm Edge Seal With Lip Elements And O-Rings
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Solution Overview
Problem
Diaphragm pumps face challenges in maintaining a proper seal and extending the life of diaphragms, especially when pumping harsh, corrosive, or acidic fluids, due to the tendency of fluoropolymer materials like PTFE to creep or cold flow, leading to potential leaks and increased pump size requirements.
Innovation Solution
A diaphragm assembly with lip elements at the periphery for sealing, utilizing O-rings that engage with groove walls to create a self-energizing seal, resisting leakage and providing anti-extrusion backup, even under increasing pressure, and a double diaphragm arrangement with porous mesh for leak detection, using compatible materials like PTFE for harsh fluid compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluoropolymer materials like PTFE are used for diaphragms to resist harsh fluids, then chemical resistance is improved, but the diaphragm tends to creep or cold flow over time, making sealing difficult
Solution Approach 1:
The patent uses a composite structure combining PTFE diaphragm material with elastomeric sealing components (O-rings and lips). The PTFE provides chemical resistance while the elastomeric materials provide creep resistance and sealing capability, creating a hybrid system that leverages the advantages of both material types.
Solution Approach 2:
The patent applies different material properties to different parts of the diaphragm assembly. The central diaphragm area uses PTFE for chemical resistance, while the peripheral sealing areas use elastomeric materials with superior creep resistance. This localized material differentiation resolves the contradiction between chemical resistance and dimensional stability.
2Reliability
If a large area of the diaphragm is clamped to limit creep, then sealing is improved, but the inactive perimeter area increases the size of the pump
Solution Approach 1:
The patent extracts the sealing function from the main diaphragm body by adding separate lip elements and O-rings. This allows the diaphragm to be clamped with minimal perimeter area since the sealing is performed by the dedicated lip and O-ring components rather than relying on large clamped areas, thus reducing pump size while maintaining sealing performance.
Solution Approach 2:
The patent segments the sealing function into distinct components (lips and O-rings) separate from the diaphragm body. This segmentation allows the diaphragm to be compact while the sealing elements provide the necessary sealing action, eliminating the need for large inactive perimeter areas.
3Force
If self-energizing seals with elastomeric O-rings are used to reduce deformation force, then sealing force is improved, but the seals must also be made of PTFE for harsh fluid compatibility, and cold flow relaxes the initial sealing force over time
Solution Approach 1:
The patent creates a composite sealing system where elastomeric O-rings provide self-energizing sealing force and PTFE lips provide chemical compatibility and creep resistance. The elastomeric material maintains its elastic properties and sealing force over time in harsh chemicals, while the PTFE structural components resist cold flow, together resolving the contradiction between initial sealing force and long-term sealing force duration.
4Reliability
If multiple layer diaphragms are used for leak detection, then leak detection capability is improved, but the crushing of separation layers must be limited, increasing complexity
Solution Approach 1:
The patent introduces a compliant separator layer as an intermediary between multiple diaphragm layers. This separator layer absorbs and distributes clamping forces, preventing direct crushing contact between rigid diaphragm layers while still allowing the multi-layer leak detection function to operate. The intermediary layer simplifies the assembly by preventing layer interaction issues.
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 ensures a reliable seal and extended diaphragm life, resistant to harsh chemicals, while maintaining a compact pump size and simplifying manufacturing and installation, effectively addressing leakage issues and compatibility with corrosive fluids.
Implementation Method 1
A first O-ring sealing element engages the first face of the disk shaped portion, a radially inner portion of the first edge portion and a wall of the frame
Implementation Method 2
These seals include elastomeric O-rings or cup seals that exert pressure on the surface to seal when fluid pressure is applied. These seals rely on some amount of initial preload that comes from the deflection of the elastic compound they are made from
Implementation Method 3
Fluoropolymer materials including polytetrafluoroethylene (PTFE), commonly sold under the names TEFLON®, and GYLON® are often used for diaphragms in metering diaphragm pumps because of their chemical resistance
Implementation Method 4
A first sealing element such as an O-ring engages the first face of the disk shaped portion, a radially inner portion of the first edge portion and a wall of the frame
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A diaphragm (18) includes a disk-shaped center planar portion (40) and a first lip (42) and a second lip (44) on the outermost edge of the disk shaped portion (40) and extending transversely to the planar disk portion (40). The first lip (42) is on a first side of the diaphragm (18) and the second lip (44) is on an opposite side of the diaphragm (18). A mounting portion (38) extends outward from the center of the face of the planar portion (40) on the first side of the diaphragm (18). For metering pump applications pumping harsh fluids, the diaphragm (18) is typically made from a fiuoropolymer and in particular may be made from polytetrafluoroethylene (PTFE).