Fire Hydrant Stem Spring Biasing for Valve Torque Reduction
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Solution Overview
Problem
Dry-barrel fire hydrants require high torque to open the main valve due to water pressure, making it difficult to initiate water flow, especially when the valve is closed.
Innovation Solution
Incorporating a spring element within the stem assembly that biases the stem towards the main valve, reducing the torque needed to open the valve by counteracting water pressure and facilitating easier operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the main valve is closed to maintain water pressure in the system, then water pressure is maintained, but high torque is required to open the valve
Solution Approach 1:
The spring element applies a preliminary opening force to the main valve before operation is initiated. This preliminary anti-action counteracts the closing force of water pressure, reducing the net torque required to open the valve while maintaining system water pressure when closed.
Solution Approach 2:
The spring element acts as a counterweight or counterbalancing force against the water pressure on the closed valve. By positioning the spring to exert an opening force on the stem, it compensates for the high torque required to overcome water pressure, making valve operation easier while preserving water pressure maintenance capability.
2Ease of operation
If a long stem is used to extend from the main valve to the top of the hydrant for operation, then the valve can be operated from above ground, but the torque required to move the stem increases
Solution Approach 1:
The spring element provides a counterbalancing opening force that acts along the length of the stem. This reduces the net force required at the top of the long stem to initiate valve opening, making the stem easier to operate despite its length and the water pressure resistance.
Solution Approach 2:
The spring applies preliminary opening force to the stem before the operator applies torque. This preliminary action reduces the initial torque requirement for moving the long stem, making remote operation from the hydrant top more feasible despite the mechanical disadvantage of the long lever arm.
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 spring element reduces the operational torque required to open the main valve, making it easier to initiate water flow and closing the valve with lower torque, thus improving the usability and efficiency of the fire hydrant.
Implementation Method 1
a spring element in the cavity of the stem, the spring element configured to bias the stem in a direction from the upper end of the stem toward the main valve
Data Source
AI summary
A fire hydrant stem includes a shaft having a center axis, a first end portion, a first end, and a second end. The first end portion extends axially a length from the first end, has external threads, and defines an internal cavity open through the first end. The second end is configured to engage a fire hydrant main valve operating assembly. A fire hydrant upper stem assembly includes a fire hydrant stem and a spring element. The fire hydrant stem defines an internal cavity, and the spring element is in the internal cavity.