Tubular Plastic Hydrant Backflow Prevention and Pressure Relief
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Solution Overview
Problem
Existing hydrants fail to effectively prevent backflow and relieve backpressure, leading to contamination and potential damage from built-up pressure, especially under freezing conditions, and often fail to meet long-term performance standards like ASSE 1019 requirements.
Innovation Solution
A compact backflow preventing valving assembly featuring an outer and inner tubular member with a sliding annular seal, a control mechanism for relative movement, and a side port for pressure relief, designed to prevent backflow and manage pressure build-up during freezing conditions, using materials like metal or pressure-expansive plastic for reliability and ease of installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spring force is increased to improve shut-off reliability, then shut-off performance is improved, but flow restriction increases
Solution Approach 1:
The patent replaces the traditional spring-based mechanical shut-off system with a positively controlled valve mechanism. The valve member is advanced by a control mechanism (such as a threaded rod or cam) that provides precise mechanical control, eliminating the need for spring force optimization. This substitution resolves the contradiction by allowing reliable shut-off through positive mechanical engagement rather than elastic force, thereby maintaining flow rate without excessive restriction.
Solution Approach 2:
The patent changes the control parameter from spring force (elastic parameter) to direct mechanical displacement (geometric parameter). By controlling the valve member's position through a threaded rod or cam mechanism, the system transitions from force-based control to position-based control, allowing independent optimization of both shut-off reliability and flow characteristics.
2Reliability
If plunger corrosion resistance is improved by material selection, then shut-off reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent replaces the plunger-based mechanical system with a valve member that slides within a valve body. This new mechanism uses a controlled sliding interface with inherent corrosion resistance through proper material selection and surface treatment, achieving reliable shut-off without the manufacturing complexity of corrosion-resistant plunger materials. The valve seat and valve member can be manufactured as simple cast or machined components.
3Reliability
If backflow prevention capability is improved, then water quality protection is improved, but pressure build-up under freeze conditions increases
Solution Approach 1:
The patent extracts the pressure relief function from the backflow prevention mechanism by providing a separate relief valve or bypass passage. This allows the main valve to maintain tight shut-off for backflow prevention while the extracted relief mechanism handles pressure build-up by opening at predetermined pressure thresholds, resolving the contradiction between backflow prevention and pressure management.
Solution Approach 2:
The patent introduces a relief valve or bypass passage as an intermediary element between the sealed valve system and the external environment. This intermediary component provides a controlled pressure release path that prevents excessive back-pressure build-up while maintaining the integrity of the backflow prevention seal, allowing both functions to coexist.
4Ease of manufacture
If valve design is simplified for ease of manufacture, then manufacturing cost is reduced, but reliability under long-term use decreases
Solution Approach 1:
The patent segments the valve into distinct functional components: a valve member for shut-off, a control mechanism for actuation, and a relief mechanism for pressure management. Each segment can be manufactured independently using simple processes (casting, machining) while maintaining high reliability through proper design of the interfaces and sealing surfaces. This segmentation allows standard manufacturing techniques to produce reliable components.
Solution Approach 2:
The patent designs the valve body and valve member with universal features that serve multiple functions: the sliding interface provides both sealing and low-friction movement, the control mechanism provides both actuation and positioning, and the relief valve provides both pressure relief and flow control. This multi-functionality reduces the total number of parts and manufacturing steps while maintaining long-term reliability.
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 prevents backflow, relieves pressure build-up, and ensures hydrant functionality under freezing conditions, enhancing reliability and compliance with performance standards by using a sliding annular seal and redundant pressure relief mechanisms.
Implementation Method 1
an annular seal extending about an axis defined by a closure member, there being an axially elongated bore defined by the outer member, and into which the seal has sliding sealing fit as the inner member is advanced
Implementation Method 2
one or both of elongated outer and inner tubular body members consist of pressure expansible plastic material
Data Source
AI summary
In a hydrant assembly, the combination comprising an outer tubular member having a first flow port.; an inner tubular member having a closure thereon to close the port in relatively axially advanced position of the closure, and to open the port in relatively axially retracted position of the closure that allows fluid flow through the port to an outlet, control means to control relative movement of the inner and outer members. A second port may be located sidewardly of the outer tubular member to pass fluid in relatively retracted position of the closure to relieve fluid pressure in space formed between the inner and outer members, the inner member being elongated and extending lengthwise in the outer tubular member. The outer tubular member may consist of plastic material. Travel of the closure acts to allow expansion of fluid as it freezes, to relieve pressure build-up within the assembly.