Diaphragm Valve Gas Tightness via Surface Roughness Control
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Solution Overview
Problem
Existing direct-touch diaphragm valves used for high-pressure, high-concentration fluorine gas supply suffer from gas leakage due to surface corrosion and poor gas tightness, primarily caused by adiabatic compression and corrosion product adhesion in the valve chamber.
Innovation Solution
The valve design includes a diaphragm and valve seat with controlled surface roughness (0.1 to 10.0 µm), curvature radius (100 to 1000 mm), and area ratio (0.2 to 10%) to enhance gas tightness, using materials with high elastic modulus for the diaphragm and corrosion-resistant materials for the valve components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large valve chamber is used to supply high-pressure fluorine gas, then the gas supply capacity is improved, but the inner temperature increases due to adiabatic compression causing surface corrosion and gas leakage
Solution Approach 1:
The invention applies different surface roughness characteristics to different regions of the valve seat. The contact surface with the diaphragm has a specific roughness range (Ra 0.1-10.0 μm) to prevent adhesion, while other regions may have different characteristics. This local differentiation allows the valve to maintain gas tightness while handling high-pressure corrosive gases.
Solution Approach 2:
The invention changes the surface roughness parameter of the valve seat contact surface to a specific range (Ra 0.1-10.0 μm). This parameter change prevents the adhesion of corrosion products between the valve seat and diaphragm, thereby maintaining gas tightness under high-pressure conditions without compromising gas supply capacity.
2Productivity
If the valve operates with high-pressure high-concentration fluorine gas, then cleaning efficiency is improved, but corrosion product adhesion to the valve seat causes gas leakage
Solution Approach 1:
The valve seat contact surface is given a specific surface roughness (Ra 0.1-10.0 μm) that differs from other surfaces in the valve. This local quality enhancement prevents corrosion product adhesion at the critical sealing interface, allowing the valve to maintain gas tightness during high-efficiency cleaning operations with high-concentration fluorine gas.
Solution Approach 2:
The invention converts the potentially harmful effect of surface smoothness (which would cause adhesion) into a beneficial controlled roughness. The specific roughness range (Ra 0.1-10.0 μm) creates a surface that prevents adhesion of corrosion products, thereby converting what would be a harmful adhesion effect into a beneficial non-adhesion property that maintains gas tightness.
3Reliability
If the valve seat surface is made smooth to reduce adhesion, then gas tightness is improved, but surface corrosion susceptibility increases
Solution Approach 1:
The invention optimizes the surface roughness parameter to a specific range (Ra 0.1-10.0 μm) that balances two opposing requirements: it is smooth enough to prevent adhesion of corrosion products and maintain gas tightness, but rough enough to reduce susceptibility to surface corrosion. This parameter optimization resolves the contradiction between gas tightness and corrosion resistance.
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 improved design significantly reduces gas leakage, maintaining excellent gas tightness even under high-pressure conditions, as demonstrated by leak detection tests showing minimal leakage after repeated cycles.
Implementation Method 1
the contact surface of the valve seat has a surface roughness Ra of 0.1 to 10.0 μm
Implementation Method 2
it is possible to improve the gas tightness of a diaphragm valve by controlling, at contact surfaces of a valve seat and a diaphragm of the diaphragm valve, a surface roughness of the contact surface of the valve seat
Implementation Method 3
a stem adapted to move a center portion of the diaphragm downwardly; and a driving unit adapted to move the stem in a vertical direction
Implementation Method 4
a valve body having inlet and outlet passages and allowing flow of halogen gas or halogen compound gas therethrough
Implementation Method 5
a curvature radius Ra of 100 to 1000 mm
Implementation Method 6
The inside of the valve chamber becomes more susceptible to surface corrosion, resin deterioration etc. as the inner temperature of the valve chamber increases
Data Source
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AI summary
A direct-touch diaphragm valve according to the present invention includes a valve body having inlet and outlet passages, a valve chamber being in communication with the inlet and outlet passages, a valve seat located around an open inner end of the inlet passage, a diaphragm arranged on the valve seat so as to hermetically seal the valve chamber and open or close the inlet and outlet passages, a stem adapted to move a center portion of the diaphragm downwardly and a driving unit adapted to move the stem in a vertical direction, wherein the valve seat and the diaphragm have respective contact surfaces formed therebetween such that: such that: the contact surface of the valve seat has a surface roughness Ra of 0.1 to 10.0 µm and a curvature radius Ra of 100 to 1000 mm; and the area ratio Sb/Sa of a contact area Sb of the valve seat with the diaphragm to a gas contact surface area Sa of the diaphragm ranges from 0.2 to 10%. The valve according to the present invention attains sufficient gas tightness and can suitably be applied to a halogen gas- or halogen compound gas-filled container.