Convex Non-Return Device Resists Inversion Under Pressure
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Solution Overview
Problem
Conventional non-return devices for liquid seal traps face issues such as evaporation of the liquid seal, siphon effects breaking the seal, and potential blockages due to restricted flow, as well as turning inside out under pressure differentials, which compromise their effectiveness in preventing odor and gas leakage.
Innovation Solution
A non-return device with a convex transition portion and moveable sheet members that are biased to return to a sealed position, allowing for increased fluid volume and flow rate while resisting pressure differentials, and featuring stiffening and biasing members to maintain sealing and prevent turning inside out.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a non-return device is incorporated into a waste trap, then odor and gas leakage is prevented, but fluid flow is restricted causing build-up and potential blockages
Solution Approach 1:
The non-return device uses a flexible membrane made of thin film material that can deform under pressure. The membrane remains relatively flat during normal operation to minimize flow restriction, but deflects under pressure differentials to close the aperture and prevent odor leakage, thus resolving the contradiction between maintaining open flow and preventing gas passage.
Solution Approach 2:
The membrane transitions from a static barrier to a dynamic component that actively responds to pressure conditions. During normal drainage, the membrane remains open and flat to allow free flow. When pressure differential exceeds a threshold, the membrane deflects and closes to block gases, providing adaptive flow management that resolves the flow restriction issue.
2Reliability
If pressure differential acts across the non-return device, then sealing is maintained, but the device turns inside out negating the sealing effect
Solution Approach 1:
The membrane is pre-formed with a curvature opposite to the expected pressure-induced deformation. When pressure differential acts on the membrane, this pre-formed curvature acts as a counterweight, resisting the turning inside out effect and maintaining the membrane's structural integrity and sealing function under pressure.
Solution Approach 2:
The membrane incorporates a pre-formed curvature or domed shape that provides structural rigidity while maintaining flexibility. This curvature geometry resists the turning inside out effect by distributing pressure forces more evenly across the membrane surface, preventing inversion while allowing the membrane to deflect for sealing.
3Reliability
If the liquid seal evaporates over time, then the trap becomes ineffective, but adding a non-return device increases complexity
Solution Approach 1:
The non-return device is integrated directly into the trap structure, with the membrane incorporated into the existing trap body and aperture. This merging of functions eliminates the need for separate components, reducing overall device complexity while providing continuous odor protection regardless of liquid seal condition.
Solution Approach 2:
The membrane-based non-return device operates automatically based on pressure differential without requiring external control or maintenance. The membrane self-adjusts its position based on flow conditions, providing continuous sealing functionality that complements the liquid seal without adding complex control mechanisms.
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 enhances the flow rate through the device, maintains an effective seal, and prevents the device from turning inside out under pressure, reducing the likelihood of blockages and odor leakage, while using thinner materials to reduce costs and improve sealing performance.
Implementation Method 1
allows fluid to build up in the immediate vicinity of the sealing portion, permitting a larger volume of fluid to be held by the device
Implementation Method 2
the members are forced apart by a flow of fluid flowing from the device inlet to the device outlet
Implementation Method 3
the sheet members being biased to return to the sealed position from the open position such that fluid is prevented from flowing from the device outlet to the device inlet
Implementation Method 4
the convex shape is also resistant to turning inside out in response to a pressure differential across the device, as the pressure has to overcome the bias of the transition portion which is to a bowed out configuration
Data Source
AI summary
A non-return device (10) for use with a waste trap is described. The non-return device comprises a sealing portion (12) having first and second sheet members (14, 16), a device inlet (18), a device outlet (20) and a transition portion (22) providing fluid communication between the device inlet and the sealing portion. The transition portion has a convex section of wall (24).