Cryogenic Vial Cap Assembly for Gas-Tight LN2 Vapor Storage
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Solution Overview
Problem
Conventional cryogenic vials fail to maintain fluid-tight closure integrity at liquid nitrogen vapor phase temperatures due to elastomer contraction and reduced internal pressure, leading to gas ingress and pressure imbalance.
Innovation Solution
A container and cap assembly with a cap comprising a first section of elastomeric material and a second section of non-pierceable thermoplastic resin, forming a snap-fit and interference fit with a body sealing surface, and optionally a foil seal for hermetic closure, ensuring fluid-tightness from ambient to cryogenic temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an elastomeric gasket or O-ring is used for sealing between the cap and vial, then the seal maintains container closure integrity down to -80°C, but the elastomer loses elasticity and contracts excessively when cooled to liquid nitrogen temperatures, causing the seal to fail
Solution Approach 1:
The patent changes the material parameter of the sealing component from elastomeric to rigid plastic, which fundamentally alters how the seal responds to temperature changes. The rigid plastic material maintains its dimensional stability and sealing capability at liquid nitrogen temperatures where elastomers fail due to excessive contraction and loss of elasticity.
Solution Approach 2:
The patent employs a composite sealing structure combining a rigid plastic cap body with an elastomeric O-ring seal. This composite approach allows the rigid plastic to provide structural integrity and dimensional stability at cryogenic temperatures, while the elastomeric O-ring provides the necessary sealing function, achieving both requirements simultaneously.
2Reliability
If a plastic-to-plastic vial and cap junction is used without elastomeric gasket, then the container closure exhibits better closure integrity, but gas still enters the vial due to reduced internal pressure from cooling, resulting in pressure imbalance
Solution Approach 1:
The patent applies different material properties to different parts of the sealing system: the cap body is made of rigid plastic for structural integrity, while an elastomeric O-ring is placed at the critical sealing interface. This local differentiation allows each component to perform its optimal function - the rigid plastic maintains dimensional stability while the elastomeric O-ring adapts to pressure changes and maintains sealing under vacuum conditions.
Solution Approach 2:
The elastomeric O-ring acts as an intermediary sealing element between the rigid plastic cap and vial. This intermediate component compensates for the pressure differential created during cooling by its elastic properties, preventing gas ingress that would otherwise occur through the rigid plastic-to-plastic junction.
3Ease of manufacture
If conventional screw caps with elastomeric gaskets are used, then the seal is simple and easy to manufacture, but the seal fails at liquid nitrogen temperatures due to elastomer contraction
Solution Approach 1:
The patent uses a composite construction where a rigid plastic cap body is combined with an elastomeric O-ring seal. This composite approach maintains ease of manufacture through standard molding techniques while achieving cryogenic seal integrity by leveraging the complementary properties of the two materials - the rigid plastic provides dimensional stability and the elastomer provides adaptive sealing.
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
Maintains container closure integrity and sterility for biological substances by preventing gas ingress and pressure imbalance, even at extreme cryogenic temperatures, thus preserving the integrity of stored materials.
Implementation Method 1
The cap has an outer surface that comprises a cap sealing surface configured to engage in an interference fit and optionally a snap-fit with the body sealing surface when the cap is inserted into the opening
Implementation Method 2
The first section is formed of a first material adapted to be pierceable by conventional hypodermic needles
Implementation Method 3
The second section is formed of a second material adapted to not be pierceable by conventional hypodermic needles
Implementation Method 4
During storage, gas will enter the vial due to the reduced internal pressure produced by cooling from ambient to LNVP temperatures
Data Source
AI summary
Disclosed are container and cap assemblies for cryogenic storage of materials at temperatures below negative 150° C. The container and cap assemblies disclosed maintain container closure integrity and fluid-tightness at ambient and cryogenic temperatures, optionally to preserve biologically active substances stored therein.