Double-Walled Shear Valve Interstitial Leak Detection
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Solution Overview
Problem
In fueling environments, existing double-walled shear valves do not effectively contain leaks at the shear valve point, leading to potential environmental damage due to undetected breaches in both the inner and outer piping, and lack of secondary containment for internal fuel dispenser piping, which can result in fuel leakage to the ground.
Innovation Solution
A double-walled contained shear valve design with an inner housing and outer containment housing forming an interstitial space, where a vacuum or pressure can be monitored for leaks, and a vacuum actuator controls the main poppet valve to close the fuel flow path in case of a leak or shear, ensuring secondary containment and leak detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If double-walled piping is used to contain fuel leaks, then leak containment capability is improved, but the ability to detect breaches in the piping remains insufficient
Solution Approach 1:
A vacuum-transmitting fluid is introduced into the interstitial space between the inner and outer piping. This fluid acts as an intermediary that transmits vacuum levels from the interstitial space to the process being monitored, enabling detection of breaches while maintaining the leak containment function of the double-walled structure.
2Reliability
If the shear valve is designed to close in response to loss of vacuum, then leak response capability is improved, but the complexity of the valve system increases
Solution Approach 1:
The shear valve incorporates a vacuum actuator that automatically responds to loss of vacuum in the interstitial space by closing the valve. This self-service mechanism eliminates the need for external monitoring systems or manual intervention, enabling automatic leak response while keeping the system relatively simple.
3Difficulty of detecting and measuring
If monitoring of the interstitial space is implemented, then leak detection capability is improved, but the complexity of the monitoring system increases
Solution Approach 1:
The vacuum-transmitting fluid serves as an intermediary that simplifies monitoring by transmitting vacuum levels directly from the interstitial space to the process being monitored. This approach reduces monitoring system complexity compared to direct pressure sensing methods while maintaining high leak detection capability.
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 double-walled shear valve effectively contains leaks within the interstitial space, preventing fuel from reaching the environment and allowing for monitoring of breaches, thereby enhancing leak detection and minimizing environmental damage.
Implementation Method 1
a vacuum actuator to open or close a main poppet valve in response to vacuum generation and loss
Implementation Method 2
the interstitial space is monitored for pressure changes. If sufficient pressure changes occur, this is an indication that either the inner piping or the outer piping of the double-walled fuel piping has incurred a leak or breach
Data Source
AI summary
A double-walled contained shear valve comprises of an inner housing forming a fuel flow path, and a containment housing surrounding the inner housing, either partially or wholly, to provide a secondary containment. An interstitial space is formed between the inner housing and the containment housing as a result, and may be placed under a vacuum or pressure level to monitor for leaks. A vacuum actuator coupled to the interstitial space automatically opens and closes the fuel flow path of the shear valve in response to the vacuum level in the interstitial space to prevent leaks to the environment. The shear valve may contain a flange for connection to internal fuel dispenser piping that either does or does not includes interstitial space orifices to couple the shear valve interstitial space to the fuel dispenser piping interstitial space to monitor the vacuum or pressure level in these interstitial spaces as one contiguous space.