Fluidic Plug Unit Sealing for High-Pressure HPLC Connections
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Solution Overview
Problem
High-performance liquid chromatography (HPLC) systems face challenges in achieving tight, long-term stable connections under high pressures while minimizing dead volume and flow resistance, with existing seals failing to maintain integrity at pressures above 1000 bar due to extrusion and mechanical wear.
Innovation Solution
A fluidic plug unit and bushing unit design that forms a sealed annular space for the sealing element, ensuring it remains with the plug unit upon disconnection, using a groove region for the sealing element and a flange region for axial fixation, which allows for secure sealing and high-pressure resistance without extrusion, utilizing materials like PEEK for the sealing element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional annular sealing elements are used under high pressure, then initial sealing is achieved, but the sealing element extrudes during operation and loses prestress
Solution Approach 1:
The sealing element is designed as a flexible membrane that can deform under pressure to conform to the sealing surface, maintaining contact and sealing integrity without extrusion. The membrane's flexibility allows it to adapt to pressure changes while remaining contained within the sealing chamber.
Solution Approach 2:
The sealing approach transitions from radial sealing (conventional annular seals) to axial sealing by positioning the membrane in a plane perpendicular to the pressure direction. This dimensional change allows the sealing element to resist extrusion by distributing stress across a different geometric orientation.
2Length of moving object
If the connection length is minimized for compact pump units, then overall device size is reduced, but the number of sealing elements and connection complexity increases
Solution Approach 1:
Multiple sealing functions are integrated into a single membrane element, eliminating the need for separate sealing components. The membrane simultaneously provides sealing against pressure, prevents leakage, and maintains structural integrity across the connection interface.
Solution Approach 2:
The membrane-based sealing element serves multiple functions: it seals the connection, compensates for pressure variations, prevents extrusion, and maintains prestress across the entire operating range. This multi-functionality reduces the total component count despite the compact design.
3Stress or pressure
If piston stroke is used to produce high system pressure, then liquid pressure is increased, but dead volume in connections reduces the effective delivery volume
Solution Approach 1:
The membrane sealing element is designed to be completely removable from the connection, ensuring no residual sealing material remains in the connection chamber. This extraction capability eliminates dead volume that would otherwise be occupied by trapped sealing material, maximizing the effective delivery volume.
Solution Approach 2:
The sealing element is designed for complete removal and potential reuse, ensuring that no sealing material is left behind in the connection. This approach recovers the full volume of the connection chamber for liquid delivery, preventing volume loss to dead space.
4Length of moving object
If screw connections with small pitch are used to achieve short overall length, then device compactness is improved, but manual closure under high sealing pressure becomes difficult
Solution Approach 1:
The connection mechanism replaces traditional threaded screw connections with a membrane-based sealing system that can be secured by alternative means (such as clamps, adhesives, or friction fits). This substitution eliminates the need for fine-pitch threading, maintaining compact length while improving manual operability under high pressure.
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 provides a reliable, low-dead-volume, low-flow-resistance connection that maintains tightness and stability under dynamic loads even at extreme pressures, preventing sealing material extrusion and mechanical wear, ensuring the sealing element remains with the plug unit for easy removal.
Implementation Method 1
The sealing element (35) is composed of a material, preferably a plastic, such as polyetherketone (PEK), in particular of a polyetheretherketone (PEEK) which is capable, in the long term and at the desired long-term stability, of maintaining a sufficiently high pressure in the annular space which bounds the sealing element (35) and ensures the tightness of the connecting device
Data Source
AI summary
A fluidic plug unit for liquid-conducting components, in particular for high-performance liquid chromatography, includes a plug housing that has a plug region with a front plug region and a rear plug region which is adjoined thereto in an axial direction. The plug unit is designed for connection to a bushing unit. In a connected state of the plug unit and bushing unit, an annular space, which is substantially closed on all sides, is formed for a sealing element of the plug unit, the annular space being bounded by an outer wall of the front plug region and an inner wall of the receiving recess of the bushing unit.