Hydrant Stem Coupling Reducing Torque via Segmentation
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Solution Overview
Problem
The extended length of hydrant stems in deep installations leads to flex and increased torque requirements for opening and closing the main valve, making operation more difficult, especially under high pressure conditions, and existing solutions are costly, interfere with access, or are not backwards-compatible.
Innovation Solution
A stem coupling with a specific design featuring a coupling body with break-away features and increased upper and lower portion lengths, providing additional support and reducing flex, is used to secure the upper and lower stems, allowing for easier operation and reducing the required torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the hydrant stem length is increased to accommodate deeper installations, then the hydrant can be installed at greater depths, but the stem flex increases and operation torque increases
Solution Approach 1:
The stem assembly is divided into multiple segments: upper stem, stem coupling, and lower stem. The stem coupling acts as an intermediate support that divides the long stem into two shorter effective lengths, reducing flex and operation torque while allowing deep installation. This segmentation transforms a single long flexible element into multiple shorter rigid elements connected by a support structure.
Solution Approach 2:
The stem coupling serves as an intermediary support structure between the upper and lower stems. It provides a fixed support point that reduces the unsupported span of the stems, thereby reducing flex and operation torque. The coupling includes break-away features that allow it to fail sacrificially under extreme impact while protecting the main valve and hydrant body.
2Reliability
If the stem coupling is designed with break-away features for sacrificial failure, then predictable failure mode is achieved, but the coupling strength is reduced
Solution Approach 1:
Break-away features are pre-designed into the stem coupling structure during manufacturing. These features create predetermined weak points that will fail first under impact loads, ensuring predictable sacrificial failure. The break-away features include reduced thickness sections and notches that concentrate stress and initiate failure at specific locations before the main valve or hydrant body are damaged.
3Stability of the object's composition
If existing solutions are used to reduce stem flex, then flex reduction may be achieved, but they are costly, interfere with access, or are not backwards-compatible
Solution Approach 1:
The stem coupling is designed to nest within the hydrant body structure, with the upper stem passing through the coupling and the lower stem connected to it. This nested arrangement integrates the support function into the existing hydrant architecture without requiring external attachments or modifications to the hydrant body, maintaining backwards compatibility and avoiding interference with access.
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 stem coupling significantly reduces the operation torque needed to open and close the hydrant, improving usability and durability by increasing the moment of inertia and allowing for predictable sacrificial failure in case of impact.
Implementation Method 1
The stem coupling can significantly reduce the operation torque needed to open and close the hydrant, improving usability and durability by increasing the moment of inertia
Data Source
AI summary
A stem coupling for a hydrant includes: an upper portion defining an upper portion length from a center of a plurality of break-away features defined in the stem coupling to a first end of the stem coupling; and a lower portion defining an lower portion length from the center of the plurality of break-away features defined in the stem coupling to a second end of the stem coupling distal from the first end of the stem coupling, the lower portion length equaling at least two times the upper portion length.