Gravity-Ball PV Valve With In-Line Testing for Fuel Tank Venting
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Solution Overview
Problem
Conventional pressure-vacuum valves for fuel storage tanks are complex, prone to wear, and require frequent replacement, especially when made of plastic, and their maintenance and testing are cumbersome due to high installation heights, necessitating special equipment and posing safety concerns.
Innovation Solution
A flow-through pressure-vacuum valve with a minimal number of moving parts, designed to be field-serviceable and durable, featuring gravity-actuated ball valves that open and close passageways based on pressure differentials, allowing for efficient venting of both positive and negative pressures, and an in-line test unit for testing the valve without disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pressure-vacuum valves are used for fuel storage tanks, then the valve can provide pressure relief functionality, but the valve becomes complex and requires frequent replacement
Solution Approach 1:
The valve body is divided into multiple passageways (first, second, and third passageways) that are integrated into a single unit, with each passageway containing a specific pressure relief valve. This segmentation allows each passageway to handle different pressure scenarios independently while maintaining an overall simple structure that reduces wear and replacement frequency.
Solution Approach 2:
The pressure-vacuum valve is designed to perform multiple functions within a single device: it provides positive pressure relief through the first passageway, emergency positive pressure relief through the second passageway, and vacuum relief through the third passageway. This multi-functionality eliminates the need for separate valves for each function, reducing overall system complexity and maintenance requirements.
2Object-affected harmful factors
If pressure-vacuum valves are installed at high heights for safety, then the valve can provide adequate venting, but maintenance and testing become cumbersome and dangerous
Solution Approach 1:
The valve incorporates an in-line test unit that allows for self-testing and self-diagnosis without requiring removal from the installation location. The test unit includes a test port and test passageway that enable pressure differential testing while the valve remains installed, eliminating the need for high-altitude maintenance work and allowing operators to perform tests from ground level.
3Strength
If PV valves are made of plastic to prevent corrosion, then the valve resists chemical degradation, but the valve becomes prone to wear and requires frequent replacement
Solution Approach 1:
The valve employs a composite construction where the valve body is made of corrosion-resistant plastic material, while the valve members (balls) are made of durable materials such as stainless steel or other wear-resistant materials. This combination allows the plastic body to resist chemical corrosion from fuel vapors while the metal valve members provide the mechanical durability needed for long-term operation, eliminating the frequent replacement issues associated with pure plastic valves.
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 provides a reliable, durable, and easy-to-maintain pressure-vacuum valve system that reduces the need for frequent replacements, allows for safe and accessible servicing, and enables in-place testing, improving operational efficiency and safety.
Implementation Method 1
The first valve member is moved into the first valve seat and is held therein by gravity to close the first passageway
Implementation Method 2
The first valve member is moved from the first valve seat to open the first passageway when pressure at the tank-side opening of the valve body exceeds pressure at the vent-side opening of the valve body by a first predetermined pressure differential
Implementation Method 3
The second valve member is moved into the second valve seat and is held therein by gravity to close the second passageway
Implementation Method 4
The second valve member is moved from the second valve seat to open the second passageway when pressure at the tank-side opening of the valve body exceeds the pressure at the vent-side opening of the valve body by a second predetermined pressure differential
Implementation Method 5
The third valve member is moved into the third valve seat and is held therein by gravity to close the third passageway
Implementation Method 6
The third valve member is moved from the third valve seat to open the third passageway when pressure at the tank-side opening of the valve body is less than the pressure at the vent-side opening of the valve body by a third predetermined pressure differential
Data Source
AI summary
A flow-through pressure-vacuum valve includes a valve body having a tank-side opening and a vent-side opening. A pressure relief valve (e.g., a ball held in a corresponding seat by gravity) is positioned within a first passageway through the body. The ball is moved from the first valve seat to open the first passageway when pressure at the tank-side opening exceeds pressure at the vent-side opening by a predetermined pressure differential. A vacuum relief valve is positioned within another passageway (e.g., a serpentine passageway). The vacuum relief valve (e.g., also a ball held in a corresponding seat by gravity) is positioned within the serpentine passageway. Analogously, the ball is moved from the valve seat to open the serpentine passageway when pressure at the tank-side opening is less than the pressure at the vent-side opening by a predetermined pressure differential.