Remote Seal Fill Fluid Thermal Management
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Solution Overview
Problem
In process control environments with high temperature process fluids and cold external temperatures, existing remote seal assemblies face challenges in maintaining the fill fluid in a liquid state, as it can vaporize due to high temperatures or gel due to low external temperatures, making it difficult to accurately measure pressure.
Innovation Solution
The use of a remote seal assembly with a fill fluid made of low melting temperature fusible alloys or non-mercury based liquid metals, combined with a thermally conductive element to maintain the fill fluid temperature above its pour point and a ceramic thermal break to reduce heat transfer, allowing the pressure transmitter to be positioned closer to the process fluid while preventing fill fluid vaporization or gelation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pressure transmitter is positioned close to the process fluid, then accurate pressure measurement is improved, but the fill fluid may vaporize due to high temperature
Solution Approach 1:
A thermally conductive element is introduced as an intermediary between the process fluid and the fill fluid in the capillary. This element conducts heat away from the fill fluid to prevent vaporization while allowing the pressure transmitter to be positioned close to the process fluid for accurate measurement.
Solution Approach 2:
The thermal conductivity parameter of the capillary material is changed by selecting a thermally conductive material that can effectively transfer heat away from the fill fluid, preventing vaporization while maintaining pressure transmission accuracy.
2Measurement precision
If the pressure transmitter is positioned close to the process fluid, then accurate pressure measurement is improved, but the fill fluid may gel due to low external temperature
Solution Approach 1:
A thermally conductive element serves as a thermal mediator that prevents excessive heat loss from the fill fluid to the cold external environment, preventing gelation while allowing close positioning of the pressure transmitter for accurate measurement.
Solution Approach 2:
The thermal insulation parameter is modified by selecting appropriate thermal conductivity characteristics in the capillary and surrounding structures to maintain fill fluid temperature above its pour point in cold environments.
3Reliability
If a thermally conductive element is added to prevent vaporization, then fill fluid temperature control is improved, but device complexity increases
Solution Approach 1:
The capillary structure is designed to serve multiple functions: it contains the fill fluid for pressure transmission, provides thermal management through its conductive properties, and maintains structural integrity. This multi-functionality reduces the need for separate thermal management components.
Solution Approach 2:
The thermal management function is merged with the pressure transmission function by making the capillary itself thermally conductive rather than adding separate thermal management components, thereby reducing overall device complexity.
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
Enables accurate pressure measurement in extreme temperature environments by keeping the fill fluid in a liquid state, preventing vaporization or gelation, and reducing the risk of overheating or undercooling, thus ensuring reliable pressure transmission.
Implementation Method 1
A thermally conductive element extends continuously along the capillary from the seal body toward the coupling and into the capillary recess such that a portion of the capillary is exposed between the thermally conductive element and the coupling
Implementation Method 2
a ceramic thermal break to reduce heat transfer
Implementation Method 3
The fill fluid transfers pressure changes at the remote seal's isolation diaphragm to the pressure transmitter's isolation diaphragm
Data Source
AI summary
A remote seal assembly for a process transmitter includes a seal body containing a cavity sealed by a diaphragm. The seal body configured to be mounted to a process element containing a process fluid such that a first side of the diaphragm is exposed to the process fluid. A capillary contains a fill fluid that is in fluid communication with the cavity and a second side of the diaphragm. A coupling has a capillary recess and two cavities separated by a second diaphragm. The capillary extends through the capillary recess and connects to the coupling such that the fill fluid in the capillary is in fluid communication with one of the two cavities and the second diaphragm. A thermally conductive element preferably extends continuously along the capillary from the seal body toward the coupling and into the capillary recess without contacting the coupling.