Cage-Shielded Valve Disc for Slam-Shut Safety Devices
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Solution Overview
Problem
Conventional slam-shut safety valves in gas distribution systems face functionality impairment due to high suction forces during high flow conditions, as the valve disc is exposed to fluid flow, impeding the device's operation.
Innovation Solution
A slam-shut safety device with a cylindrical cage surrounding the valve disc, featuring flow apertures and longitudinal guides, which reduces suction force and protects the valve disc by positioning it within a recess when open, minimizing direct fluid contact and enhancing performance and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the valve disc is exposed to fluid flow in conventional slam-shut devices, then the device structure is simple, but suction forces during high flow conditions impede the functionality of the slam-shut device
Solution Approach 1:
A cage structure is introduced as an intermediary component between the fluid flow and the valve disc. The cage includes a body with flow apertures that allow fluid passage while providing a physical barrier that shields the valve disc from direct exposure to suction forces during high flow conditions, thereby protecting the valve disc while maintaining device functionality
Solution Approach 2:
The cage structure divides the flow path into separate zones: an outer flow path through the flow apertures and an inner recess area where the valve disc operates. This segmentation isolates the valve disc from the harmful fluid flow effects while maintaining the overall valve function
2Device complexity
If the valve disc is exposed to fluid flow, then the device structure is simpler, but the valve disc is directly subjected to suction forces that impede operation
Solution Approach 1:
The cage acts as a mediating structure that minimally increases device complexity while significantly improving ease of operation. By introducing this intermediate protective structure, the valve disc is shielded from suction forces, allowing smooth operation without direct exposure to harmful fluid dynamics
3Object-affected harmful factors
If the valve disc is positioned within a recess in the cage, then suction force on the valve disc is reduced, but the device structure becomes more complex
Solution Approach 1:
The valve disc is nested within the recess of the cage structure, creating a protected inner chamber. This nesting arrangement effectively shields the valve disc from suction forces while integrating the protective function into a compact design that adds minimal overall complexity to the device
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 effectively mitigates suction-induced impairment, ensuring improved functionality and reliability of the slam-shut safety device, especially in high flow situations, by shielding the valve disc and guiding its movement between open and closed positions.
Implementation Method 1
A spring is disposed within the valve body, with the spring operatively coupled to the valve disc and arranged to bias the valve disc toward the closed second position
Implementation Method 2
In certain flow conditions, such as relatively high flow conditions, suction on the valve disc may impede the functionality of the slam-shut device
Data Source
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AI summary
A slam-shut device includes a valve body (112) having an inlet (114), an outlet (116), a valve seat (120), and defining a flow path (118). A valve disc (122) is shiftable between an open position and a closed position, and a reset pin (136) responsive to an actuator (115) is coupled to the valve disc and shifts between an untripped position and a tripped position. A cylindrical cage (140) is mounted within the valve body (112) and is disposed in the flow path (118), includes a plurality of flow apertures (142) and slidably receives the valve disc (122). The cage (140) includes a first end adjacent the valve seat (120) and a second end away from the valve seat, and the cage (140) forms a cylindrical recess (154) disposed adjacent its second end and spaced from the flow apertures (142).