HPLC Capillary Connector with Radial Seal and Segmented Shells
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Solution Overview
Problem
Existing connector units for capillaries in high-performance liquid chromatography (HPLC) systems face issues with dead volume formation and deformation of sealing elements, which hinder secure connections and lead to potential damage or failure when components are replaced due to axial misalignment or pressure differences.
Innovation Solution
A connector unit with a plastically deformable inner shell and a pressure-resistant outer shell, where the inner shell extends radially beyond the outer shell to create a sealing action, preventing deformation and medium penetration, and allowing for easy connection and disconnection without dead volume formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealing element is pressed into a conical receiving opening to ensure sealing at high pressures, then sealing reliability is improved, but the sealing element and capillary deform and become locked, preventing easy disconnection
Solution Approach 1:
The connector unit is divided into distinct functional segments: a connection portion with the sealing element, a middle portion with a shouldered end region, and a capillary receiving portion. This segmentation allows the sealing element to be compressed axially during connection while preventing radial deformation that would lock it to the capillary, enabling easy disconnection by simply pulling the connector unit off the capillary.
Solution Approach 2:
The invention transitions from radial sealing (where the sealing element is pressed radially inward against the capillary) to axial sealing (where the sealing element is compressed axially between the shouldered end region and the capillary face surface). This dimensional change allows the sealing element to deform in the axial direction without becoming locked to the capillary, solving the disconnection problem while maintaining sealing reliability.
2Reliability
If the sealing point is offset rearward from the face surface to ensure sealing action, then sealing reliability is improved, but dead volume is formed which reduces measurement precision
Solution Approach 1:
The invention creates an equipotential sealing surface by positioning the sealing action exactly at the face surface level (neither offset forward nor rearward). The shouldered end region is designed so that its front surface coincides with the capillary face surface, ensuring that the sealing element compresses axially at the precise location where the capillary face surface contacts the connecting line face surface, eliminating dead volume while maintaining sealing reliability.
3Reliability
If the inner shell is made plastically deformable to create sealing action, then sealing reliability is improved, but the shell may collapse under high pressure reducing structural integrity
Solution Approach 1:
The connector unit applies local quality by making only the connection portion (with the sealing element) plastically deformable, while the middle portion and capillary receiving portion remain rigid. The shouldered end region provides localized plastic deformation for sealing, while the rest of the structure maintains structural integrity to withstand high pressures. This localized deformability ensures sealing reliability without compromising overall strength.
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
Ensures a pressure-tight connection without dead volume, prevents medium penetration between shells, and allows for reliable connection and disconnection of capillaries, even under high pressures, maintaining the integrity of the chromatography system.
Implementation Method 1
In the region of the end at which the connector unit is provided, the inner shell (10b) extends beyond the face side of the outer shell (10a) and has a front, radially outwardly extending end region (13), which, in the connected state of the connector unit (3) and bushing unit (5), generates a sealing action between the front end region (13) of the connector capillary (10) and the annular face side of the capillary receiving opening (56) of the bushing unit (5)
Implementation Method 2
Finally, the connector unit (3) should also be easily connectable to a bushing unit (5) or to a connecting unit. To attain the pressure stability, the plastics hose is embedded into a metallic pipe. To provide the necessary metal-free connections for this purpose, said capillary ends are insert molded with plastic
Data Source
AI summary
A connector unit for connecting capillaries, for high-performance liquid chromatography includes a connector capillary, a connector housing, and an annular sealing element. The connector capillary projects through a bore of the connector housing. The annular sealing element is provided on a front end region of the connector capillary and which is composed of a plastically and/or elastically deformable material. The connector capillary has an inner shell composed of a plastically and/or elastically deformable material and an outer shell which engages around the inner shell. The inner shell has a radially outwardly extending front end region which, on its own or together with the annular sealing element can generate a seal between the front end region of the connector capillary and a bushing unit.