Fire Extinguisher Nozzle Thread Geometry for Low-Temperature Impact
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Solution Overview
Problem
Handheld fire extinguishers face performance compromise due to nozzle brittleness at low temperatures, leading to potential damage from impacts, as existing polymeric nozzles become brittle and lose functionality.
Innovation Solution
A valve body and nozzle assembly design featuring a non-metallic nozzle with a root portion having radii of curvature and a metallic valve body, along with an interference fit between the nozzle and valve body sleeve portions, enhances the nozzle's ability to withstand impacts across a wide temperature range without compromising performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a polymeric nozzle is used in a fire extinguisher, then the nozzle can be manufactured with ease and cost-effectiveness, but the nozzle becomes brittle at low temperatures leading to potential damage from impacts
Solution Approach 1:
The patent applies local quality by introducing radii of curvature specifically at the root portions of the nozzle threads where stress concentrations occur during impact. This localized geometric modification enhances impact resistance at critical areas without changing the overall polymeric material or manufacturing process, thus maintaining ease of manufacture while improving reliability.
Solution Approach 2:
The patent implements spheroidality by adding radii of curvature to the root portions of the threaded sections. These curved transitions replace sharp corners with smooth rounded surfaces, which distribute stress more evenly during impact events. This curvature modification prevents stress concentration points that would otherwise lead to brittle failure in polymeric nozzles at low temperatures.
2Device complexity
If the nozzle is made from a single piece of polymeric material, then the manufacturing process is simplified, but stress concentrations occur at thread root portions during impact
Solution Approach 1:
The patent maintains the simple single-piece polymeric construction but applies local quality modifications at the thread root portions through radii of curvature. This localized geometric change addresses stress concentration issues without increasing overall device complexity or requiring multi-piece construction.
Solution Approach 2:
The patent uses spheroidality by replacing sharp corners at thread roots with curved surfaces having specified radii. This geometric transformation maintains the simplicity of single-piece polymeric manufacturing while significantly improving impact strength by eliminating stress concentration points.
3Ease of manufacture
If the nozzle is designed with standard thread configurations, then manufacturing and assembly are straightforward, but the nozzle becomes susceptible to damage during low-temperature impacts
Solution Approach 1:
The patent maintains standard threaded connection configurations for ease of manufacture and assembly but applies local quality enhancements at the thread root portions. The radii of curvature are added only where stress concentrations occur during impact, preserving manufacturing simplicity while protecting against low-temperature damage.
Solution Approach 2:
The patent incorporates spheroidality by adding radii of curvature to thread root portions while maintaining overall standard thread configurations. This selective curvature application protects against impact damage without complicating manufacturing or assembly processes.
Data Source
AI summary
A valve body and nozzle assembly for a fire extinguisher includes a valve body that includes a nozzle connection that has a valve body threaded portion. A non-metallic nozzle includes a proximal end that has a valve body connection with a nozzle threaded portion in engagement with the valve body threaded portion. The nozzle threaded portion includes a root portion that has at least one radius of curvature extending between adjacent rows of a thread of the nozzle threaded portion.