Segmented Seal Design for High-Pressure HPLC Applications
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Solution Overview
Problem
High-pressure applications in HPLC technology face challenges with existing seals due to issues of seal migration, material incompatibility, and the need for separate dynamic and static sealing properties, which are not adequately met by current solutions, particularly in terms of stability, positional security, and bio-inertness.
Innovation Solution
A sealing system comprising two distinct sealing portions, one statically stressed and made from high-strength plastics like PEEK, which can be plastically deformed for static sealing, and another dynamically stressed portion with a prestressed sliding element for dynamic sealing, connected via a thin material point to maintain sealing efficacy under high pressures without material flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single seal material is used for both dynamic and static sealing, then the device complexity is reduced, but the sealing performance for both dynamic and static conditions cannot be optimized simultaneously
Solution Approach 1:
The seal is divided into two distinct sealing portions: a first sealing portion for dynamic sealing between the seal and piston rod, and a second sealing portion for static sealing between the seal and pump head. Each portion can be made from materials optimized for its specific function, with the second portion using high-strength plastic for static sealing and the first portion using materials with good sliding properties for dynamic sealing.
Solution Approach 2:
Different regions of the seal have different material properties tailored to their specific sealing requirements. The second sealing portion uses high-strength plastic with high rigidity for static sealing, while the first sealing portion uses materials with good sliding properties for dynamic sealing, allowing each local region to have the optimal material characteristics for its function.
2Ease of operation
If thermoplastic material with good sliding properties is used for dynamic sealing, then the sliding properties are improved, but the rigidity is insufficient for high pressure applications
Solution Approach 1:
The seal separates the dynamic sealing function (requiring good sliding properties) from the static sealing function (requiring high rigidity). The second sealing portion uses high-strength plastic for static sealing against the pump head, while the first sealing portion handles dynamic sealing against the piston rod, allowing each segment to have material properties optimized for its specific requirement.
3Force
If metallic spring element is inserted for prestressing the sealing lips, then the prestressing function is achieved, but chemical reactions with the sample may occur and dead spaces are created
Solution Approach 1:
The patent replaces the metallic spring prestressing system with a prestressing element made from chemically inert material that can be integrated into the seal structure. This substitution eliminates the risk of chemical reactions between metal and sample while maintaining the prestressing function. The design also eliminates dead spaces by ensuring continuous flow paths around the prestressing element.
Solution Approach 2:
The prestressing element is made from chemically inert material (such as PEEK or other fluoroplastics) that does not react with the sample medium, creating an inert environment that prevents chemical reactions. This inert material maintains the prestressing force while being compatible with all sample substances in HPLC applications.
4Reliability
If the seal is prestressed to improve sealing at high pressure, then the sealing action is improved, but the material may be too flexible to maintain inherent prestress
Solution Approach 1:
The seal is prestressed during the installation process by pressing the second sealing portion into the sealing seat, which deforms the material and creates initial contact pressure. This preliminary action ensures that the seal is already under stress when installed, improving sealing effectiveness from the start without requiring additional flexible materials that would compromise rigidity.
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 system provides a stable and secure sealing action with minimal friction, maintaining high-pressure integrity and bio-inertness, suitable for both static and dynamic conditions, while preventing material flow through the thin connection point, ensuring reliable sealing in high-pressure environments.
Implementation Method 1
the second sealing portion (20) is plastically deformed under high pressurization, so that it completely fills the sealing seat (22) and is tightly pressed against the housing (14)
Implementation Method 2
the first sealing portion (24) is elastically compressed under the system pressure, so that it maintains a particularly good sealing action
Implementation Method 3
a sliding element (21) which bears directly against the piston rod (11), being used... with as little friction as possible
Data Source
AI summary
The invention relates to a seal for high pressure applications, in which a static and a dynamic sealing portion are separated from each other by a material thin point in such a manner that plastic flowing through the thin point is suppressed even if one of the two sealing portions is acted upon under high pressure as far as elastic compression.