Zero-Dead-Volume Tubing Fitting With Over-Compression Control
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Solution Overview
Problem
Existing zero dead volume fittings face challenges with over-tightening, deformation under high pressure, and the creation of undesirable mixing chambers due to the design and number of parts, which can lead to inefficiencies and potential damage to the tubing in analytical systems.
Innovation Solution
A high-pressure capillary tubing connector system featuring a main body, primary seal, and retaining member, where the primary seal is designed to prevent over-compression of the tubing by engaging with a zero dead volume fitting detail, and the retaining member applies controlled force to maintain the ferrule's position, ensuring a leak-tight seal without adding dead volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ferrule is deformed against the fitting to provide a seal, then a leak-tight seal is achieved, but some volume is created at the interface of these components
Solution Approach 1:
The fitting is divided into separate functional components: a reception portion that receives the tube end and a sealing portion that provides the seal. This segmentation allows the sealing surface to be positioned at the very end of the reception portion, eliminating the dead volume that would otherwise exist at the interface between the ferrule and fitting body.
Solution Approach 2:
The sealing mechanism transitions from radial compression (ferrule deforming against tube) to axial sealing (sealing portion contacting tube end face). By moving the sealing action to the axial dimension at the tube end, the design eliminates the radial interface volume that creates dead space.
2Reliability
If the ferrule is made sufficiently large to provide a seal, then sealing capability is improved, but the force necessary to deform the ferrule may exceed the tubing strength and overdrive the tubing into the fitting
Solution Approach 1:
The fitting is segmented into a reception portion and a sealing portion. The reception portion is designed to receive and support the tube end, while the sealing portion provides the actual seal. This segmentation allows the sealing force to be applied locally at the tube end face rather than requiring large radial compression forces that could damage the tubing.
Solution Approach 2:
The sealing function is extracted from the ferrule-deformation mechanism and placed into a dedicated sealing portion of the fitting. This extraction eliminates the need for excessive ferrule deformation forces, as the sealing is achieved through the geometric design of the sealing portion contacting the tube end face directly.
3Adaptability or versatility
If multiple ports are present in the valve, then functionality is improved, but the risk of overtightening into one or more ports increases
Solution Approach 1:
Each port is equipped with its own reception portion and sealing portion, creating independent sealing zones. This segmentation ensures that tightening forces are localized to each port's specific sealing area, preventing the propagation of excessive forces to adjacent ports and eliminating the risk of overtightening damage in multi-port configurations.
4Volume of stationary object
If the fitting design allows tube ends to butt directly to each other or have matching bores, then dead volume is minimized, but the complexity of maintaining precise alignment and seal integrity increases
Solution Approach 1:
The fitting is segmented into a reception portion that precisely receives the tube end and a sealing portion that provides the seal. This segmentation creates a guided insertion path where the tube end is received and positioned by the reception portion, then sealed by the sealing portion, simplifying alignment while maintaining zero dead volume.
Solution Approach 2:
The reception portion is designed to preliminarily position and guide the tube end into the correct alignment before the sealing portion engages. This preliminary action ensures proper alignment is achieved automatically during insertion, eliminating the need for complex external alignment procedures while maintaining the zero dead volume configuration.
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 effectively prevents over-driving of the tubing, maintains a leak-tight seal, and minimizes dead volume, thereby enhancing the efficiency and reliability of analytical systems under high pressure conditions.
Implementation Method 1
the primary seal is designed to prevent over-compression of the tubing by engaging with a zero dead volume fitting detail
Implementation Method 2
the retaining member applies controlled force to maintain the ferrule's position, ensuring a leak-tight seal
Implementation Method 3
deform the ferrule against the mating wall of the fitting detail, causing the ferrule to apply pressure to the tubing and force such tubing against the bottom of the fitting detail
Data Source
AI summary
The disclosure pertains to an assembly for use in connecting tubing to a fitting with zero dead volume.