Serviceable Shutoff Valve with Excess Flow and Pressure Equalization
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Solution Overview
Problem
Traditional stop valves lack automatic shutoff and pressure equalization capabilities in liquefied natural gas systems, particularly due to insulation requirements and the need for heavy protective cages to prevent accidental gas loss in case of external impacts or accidents, which complicates the safe transportation and storage of flammable liquids and gases.
Innovation Solution
An in-line serviceable shutoff valve with excess flow capability is designed, featuring a separable cover that allows internal component servicing without disconnecting from the pipeline, including a bonnet for cryogenic applications and a break-away safety mechanism to reduce the need for protective cages, enabling automatic closure and pressure equalization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional gate valves or ball valves are used in liquefied natural gas systems, then the shut-off function during fire is adequate, but the automatic shutoff capability when there is leakage downstream is lacking
Solution Approach 1:
The valve incorporates an automatic shutoff mechanism that activates when leakage is detected downstream. The valve body includes a diaphragm and spring assembly that automatically closes the valve when pressure differential indicates downstream leakage, eliminating the need for external control systems or complex sensing mechanisms.
Solution Approach 2:
The valve utilizes pneumatic pressure differential across a diaphragm to trigger automatic shutoff. When downstream pressure drops due to leakage, the pressure differential causes the diaphragm to move and close the valve, providing automatic protection without complex electronic or mechanical control systems.
2Ease of operation
If traditional stop valves are mounted within storage tanks for propane, then the valve is accessible, but the same mounting approach cannot be used for liquefied natural gas tanks due to insulation requirements
Solution Approach 1:
The valve is designed to be mounted externally on the insulated tank surface rather than internally within the tank. The valve body includes an insulated bonnet that interfaces with the tank insulation, allowing the valve to be positioned in a different spatial dimension (external vs. internal) while maintaining compatibility with insulated tank structures.
Solution Approach 2:
The valve design incorporates features that make it universally applicable to both insulated and non-insulated tanks. The valve body and bonnet configuration can accommodate different tank types, and the external mounting approach works for various tank materials and insulation configurations, providing multi-functional adaptability.
3Reliability
If heavy protective cages are added to ball and gate transfer valves, then the valve integrity is protected against external impact, but the overall device weight and complexity increase
Solution Approach 1:
The patent removes the need for heavy protective cages by extracting the vulnerability of traditional valves through design changes. The valve incorporates an inherently safer design with a valve body that can withstand impact forces without requiring external protective structures, eliminating the added weight and complexity of cages.
Solution Approach 2:
The valve design incorporates built-in impact resistance features that cushion against external forces before damage can occur. The valve body geometry and material selection provide inherent protection against impact, reducing or eliminating the need for additional protective cages.
4Reliability
If additional T lines are added for pressure equalization, then the trapped vaporized gas can be relieved, but the device complexity and number of components increase
Solution Approach 1:
The valve integrates pressure equalization functionality directly into the valve body structure. The design combines the shutoff function with pressure relief capability, allowing trapped vaporized gas to be equalized through the valve mechanism itself rather than requiring separate T lines and additional piping configurations.
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 valve provides automatic shutoff and pressure equalization, enhancing safety and compliance with regulatory standards by eliminating the need for heavy protective cages and additional T lines, while maintaining valve integrity and reducing the risk of accidental gas release.
Implementation Method 1
The valve also includes an automatic excess flow protection that closes the valve when fluid flow exceeds a predetermined limit
Implementation Method 2
A central poppet is held open by a mechanical linkage with the control lever so that a small amount of fluid may flow through the center of the seat, which allows pressure equalization once downstream pressure is re-gained
Implementation Method 3
A set spring biases the valve plug to a closed position in which the valve plug contacts the valve seat to prevent fluid flow through the valve
Implementation Method 4
which allows pressure equalization once downstream pressure is re-gained
Data Source
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AI summary
An in-line serviceable cutoff valve with excess flow capability includes a valve body and a separable cover. Internal valve components are accessible for service or replacement when the separable cover is removed from the valve body. The internal valve components may optionally be attached to the separable cover so that the separable cover and the internal valve components may be removed as a single assembly.