Aseptic Valve Diaphragm Threading for Stable PTFE Sealing
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Solution Overview
Problem
Aseptic valves face issues with diaphragm material recompression under cyclic pressure changes, leading to dimensional changes and potential failure in sealing, especially due to the use of PTFE diaphragms which can suffer from cold flow and stress, causing variability in the valve's sealing performance over time.
Innovation Solution
A fluid shut-off device design featuring a self-tapping stem thread that securely engages with the diaphragm, minimizing deformation and maintaining a firm connection between the control stem and diaphragm, ensuring a stable seal by reducing recompression and maintaining precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PTFE diaphragms are used in clean and aseptic valves, then the valves meet CIP and SIP requirements with compact design and minimal cleaning solution use, but the diaphragms undergo recompression under cyclic pressure changes leading to dimensional changes and potential sealing failure
Solution Approach 1:
The patent changes the geometric parameters of the diaphragm by introducing a recess that receives a positioning element. This structural modification alters how the diaphragm deforms under pressure, compensating for recompression effects and maintaining stable sealing performance throughout the valve's operational life.
2Ease of operation
If the diaphragm is pressed during closing by the control member, then the valve can close, but the diaphragm changes size over time modifying the correct sealing closing position
Solution Approach 1:
The patent replaces the traditional mechanical pressing action with a positioning system. A positioning element with a specific profile engages with a recess in the diaphragm, mechanically guiding and limiting the diaphragm's movement to maintain the correct sealing position without excessive compression that would cause dimensional changes over time.
3Ease of operation
If the control member pulls the diaphragm during opening, then the valve can open, but the pulling action loosens the grip creating displacement and clearance
Solution Approach 1:
The patent creates a dynamic positioning system where the control member's profiled positioning element interacts with the diaphragm's recess. During opening, the positioning element allows controlled movement while maintaining engagement, preventing loosening and clearance. The system adapts to the diaphragm's movement while maintaining a firm connection throughout the operational cycle.
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 significantly reduces diaphragm deformation and recompression, ensuring a prolonged life of the valve under severe conditions, with minimal changes in volume and thickness, maintaining a perfect seal over time and allowing for numerous cycles without failure.
Implementation Method 1
a self-tapping stem thread (27) which screws on by entering into the body of said diaphragm (8) thus creating a diaphragm thread (28) in the diaphragm seat (11), thus creating a close coupling between the profile of said self-tapping stem thread (27) and said body of the diaphragm (8)
Implementation Method 2
The control stem (13) transmits a movement to said diaphragm sealing portion (9), said control stem (13) being so close-coupled to said diaphragm body that an attempt to unscrew the parts would involve breaking the diaphragm (8)
Implementation Method 3
PTFE, when stressed by cyclic compression, is subject to sliding (cold flow) if it is not obtained by compression
Implementation Method 4
the diaphragm sealing portion (9), in the closing position of the inlet duct (3), cooperates, by means of a diaphragm support surface (20), with said sealing surface (14) to occlude said inlet duct (3)
Data Source
Figure 1
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AI summary
Fluid shut-off device (1) comprising a valve body (2); an inlet duct (3) having a predetermined transverse inlet duct dimension (Di)