Gallium Alloy Transfer Fluid for High-Temperature Diaphragm Seals
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Solution Overview
Problem
Diaphragm seals with hydraulic pressure transfer systems face issues in high-temperature, low-pressure applications, where the pressure transfer liquid outgasses or decomposes, leading to measurement errors and potential plastic deformation due to reactions with impurities or surfaces, especially in vacuum applications with temperatures up to 400°C and pressures below 1 bar absolute.
Innovation Solution
A gallium-based alloy, particularly a eutectic gallium-based alloy with a melting temperature less than 20°C and a high boiling point, is used as the pressure transfer liquid, ensuring stability and preventing decomposition by selecting a composition with at least 50% gallium and additional components like indium, tin, zinc, lead, or bismuth, which maintain a stable phase under process conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silicone oil is used as pressure transfer liquid, then the pressure transfer means works under usual process conditions, but the pressure transfer liquid outgasses or decomposes at high temperatures (≤400°C) and low pressures (≤1 bar)
Solution Approach 1:
The patent changes the physical and chemical parameters of the pressure transfer liquid by using a gallium-based alloy with specifically selected composition (at least 50 mass% gallium, melting point <20°C) instead of conventional silicone oil. This parameter change enables the liquid to maintain stability at high temperatures (≤400°C) and low pressures (≤1 bar) where silicone oil would outgas or decompose.
Solution Approach 2:
The patent employs a composite alloy material consisting of gallium combined with other metals (such as indium, tin, zinc, lead, or bismuth) to create a eutectic composition. This composite material achieves both low melting point (<20°C) and high boiling point (>2400°C), resolving the contradiction between operational temperature range and stability.
2Measurement precision
If the pressure transfer liquid is exposed to high temperature and low pressure, then measurement can be performed, but the liquid reacts with impurities or surfaces causing plastic deformation
Solution Approach 1:
The gallium-based alloy creates an inert environment within the pressure transfer system. The alloy's high chemical stability at elevated temperatures prevents reactions with impurities or surface materials, eliminating the harmful effects that would otherwise cause plastic deformation and measurement errors while maintaining measurement precision.
Solution Approach 2:
By changing the chemical composition parameters of the pressure transfer liquid to use a gallium-based alloy with specific properties (high boiling point, low melting point, chemical inertness), the system can operate at high temperatures without the liquid reacting with surrounding materials, thus preventing plastic deformation.
Data Source
AI summary
The present disclosure is directed to a method of using a gallium-based alloy, such as a eutectic, gallium-based alloy, as pressure transfer liquid in a hydraulic pressure transfer means for determining a process pressure in a process, in which the process medium has a process temperature ≤400° C. and a process pressure <1 bar absolute, wherein the alloy contains, besides gallium, furthermore, at least one other component and the mixing ratio between gallium and the at least one other component is selected in such a manner that the alloy has a melting temperature less than 20° C.