Capillary Tube Sealing Plug for Low-Dead-Volume HPLC Connections
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Solution Overview
Problem
Existing capillary tube connection systems in high-performance liquid chromatography (HPLC) face issues with dead volume creation due to axial tolerance differences and the risk of sealing element deformation or detachment, especially when using thinner capillary tubes with smaller diameters and varying receptacle opening depths, leading to unreliable connections and potential damage.
Innovation Solution
A capillary tube connection system featuring a plug with a sealing element having a convex first end section and a larger second end section, combined with a pressure piece that exerts axial force, allowing for alignment and secure sealing of capillary tubes with different diameters and compensating for axial tolerances, while preventing the sealing element from detaching from the capillary tube during disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sealing elements with conical profiles are pressed into conical receptacle openings to ensure tight connections under high pressure, then sealing reliability is improved, but the sealing position is offset from the capillary tube end surface, creating dead volume
Solution Approach 1:
The sealing element geometry is changed from a conventional conical profile to a specific profile with a sealing edge that can form a seal at or near the capillary tube end surface. This parameter change in the sealing element's shape allows the sealing position to be optimized, reducing dead volume while maintaining sealing reliability under high pressure conditions.
2Reliability
If sealing elements are pressed with high axial pressure to guarantee tight connections, then sealing performance is improved, but the sealing element deforms and creates a positive-fit connection that prevents easy repositioning
Solution Approach 1:
The sealing element is designed with differentiated local properties: a sealing edge region optimized for forming tight seals under pressure, and a body region with geometric features (such as a groove or reduced diameter section) that prevent excessive deformation and positive-fit crimping. This local quality differentiation allows the sealing surface to deform for sealing while the body maintains enough rigidity to allow repositioning.
3Adaptability or versatility
If capillary tubes with different outer diameters are connected to bushing units with conventional receptacle openings, then adaptability is improved, but dead volume increases and connection reliability decreases
Solution Approach 1:
The sealing element is designed as a universal component that can accommodate capillary tubes with different outer diameters. The sealing element's geometry, particularly its sealing edge and body profile, is optimized to work with various capillary tube sizes while maintaining consistent sealing performance and minimal dead volume, eliminating the need for diameter-specific sealing elements.
4Ease of manufacture
If the receptacle opening depth varies due to tolerances or manufacturing differences, then manufacturing flexibility is improved, but connection reliability deteriorates due to inconsistent sealing positions
Solution Approach 1:
The sealing element incorporates a design feature (such as a groove, reduced diameter section, or specific geometric profile) that acts as a stop or reference point before the sealing edge. This beforehand cushioning feature ensures that the sealing edge always reaches the same position relative to the capillary tube end surface, compensating for variations in receptacle opening depth and maintaining consistent sealing quality despite manufacturing tolerances.
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
This solution provides a compact, reliable, and easy-to-assemble sealing system that ensures a tight and consistent fluid flow, reduces the risk of dead volume creation, and prevents sealing element detachment, enhancing the reliability and flexibility of capillary tube connections in HPLC systems.
Implementation Method 1
an extremely high, radially inward pressure is exerted by means of an attachment screw onto the front region of the sealing element, so that the sealing position is realized
Implementation Method 2
Through the high pressure deformation of the sealing element and the capillary tube can be generated, wherein the sealing element is pressed with its front edge in an annular shape into the outer periphery of the capillary tube
Data Source
AI summary
A plug for connecting capillaries includes at least one capillary tube, at least one sealing, and at least one pressure piece. The capillary tube includes a first inner diameter and an open end section. The sealing includes a second inner diameter, a first end section and a shape adapted to seal the open end section of the capillary tube when connected. The pressure piece is adapted to exert at least axial pressure and/or force to at least a part of the sealing. The pressure piece is also adapted to host the first end section of the sealing in abutment with the open end section of the capillary tube so that the capillary tube and the sealing are aligned.