Expansion Vessel Membrane Sealing to Prevent Gas Permeation
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Solution Overview
Problem
Existing diaphragm pressure expansion vessels with elastomeric membranes suffer from gas permeation issues, where gas from the gas space penetrates into the water space over time, leading to undesirable gas loss and the need for frequent refilling in heating circuits.
Innovation Solution
A membrane pressure expansion vessel with a gas-impermeable plastic membrane, such as an ethylene-vinyl alcohol copolymer (EVOH), and a C-shaped sealing element made of sealing foam applied to the outer edge of the membrane ensures a reliable seal without additional assembly effort, preventing gas permeation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an elastomeric membrane is used to separate the water and gas spaces, then the membrane provides good elasticity and sealing, but gas permeation occurs over time requiring maintenance
Solution Approach 1:
The patent applies a composite membrane structure consisting of an elastomeric base layer providing elasticity and sealing, combined with a gas-impermeable plastic coating layer (such as EVOH, polyamide, or polyvinylidene chloride) that prevents gas permeation. This composite structure resolves the contradiction by combining the advantages of both materials while eliminating their individual disadvantages.
2Reliability
If a gas-impermeable plastic membrane is used to prevent permeation, then gas loss is prevented, but the membrane loses elasticity and sealing capability
Solution Approach 1:
The patent uses a composite membrane where the elastomeric base layer maintains sealing capability and elasticity, while the plastic coating layer provides gas impermeability. The coating is applied in a thickness range of 1-20 micrometers to ensure gas barrier properties without compromising the underlying elastomer's mechanical properties.
3Reliability
If additional sealing elements are added to prevent gas permeation, then sealing is improved, but manufacturing and assembly costs increase
Solution Approach 1:
The patent merges the sealing function with the membrane structure itself by integrating a sealing bead directly into the membrane assembly. This eliminates the need for separate sealing elements and additional assembly steps, thereby improving sealing reliability while keeping manufacturing and assembly costs manageable.
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 effectively prevents gas permeation from the gas space into the water space, maintaining the gas volume and reducing maintenance needs, while keeping manufacturing and assembly costs manageable.
Implementation Method 1
a plastic membrane (6) which is gas-impermeable, as a result of which permeation of gas, in particular of air or nitrogen, is avoided
Implementation Method 2
a C-shaped sealing element (11) made of sealing foam applied to the outer edge of the membrane
Data Source
AI summary
The vessel (1) has a vessel interior chamber closed by two vessel parts (2, 3). The interior chamber is separated into a water chamber (7) and a gas chamber (8) by a flat and/or semi-shell shaped membrane (6). The water chamber is connected with a line network by a connection support (5). The membrane is made of single-layer gas impermeable plastic and is connected with a sealing element at an outer edge of the membrane. The outer edge of the membrane is integrated into a connection region (4) between the vessel parts in a fluid-tight manner.