Balanced Outlet Nozzle for Quiet Inert Gas Fire Suppression

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Solution Overview

Problem

Inert gas fire suppression systems generate high sound levels due to supersonic gas discharge, which can damage sensitive electronic components, and previous attempts to reduce sound levels have resulted in reduced coverage area and height, making it difficult to retrofit existing systems without substantial modifications.

Innovation Solution

The development of low pressure drop acoustic suppressor nozzles that balance gas flow through multiple outlet holes and use a pressure reducing device upstream to minimize sound power while maintaining effective gas discharge for fire suppression, with sound power levels no greater than 130 dB and pressure drop no more than 80 psi higher than enclosure gage pressure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If inert gas is discharged at supersonic velocities to meet fire suppression standards, then the oxygen reduction speed and coverage area are improved, but the sound power level increases to harmful levels

Engineering Contradiction:

Improveoxygen reduction speedVSAvoidsound power level

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The nozzle divides the single high-velocity jet into multiple lower-velocity streams by creating multiple outlet holes arranged in concentric circles. This segmentation reduces the velocity of individual gas streams while maintaining the total flow rate, thereby reducing sound power levels from supersonic levels to below 130 dB while preserving the oxygen reduction capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different properties to different parts of the gas discharge system by varying the diameter, spacing, and distribution of outlet holes across concentric circles. This creates localized variations in flow characteristics that collectively reduce overall sound power while maintaining effective coverage area and oxygen reduction speed.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If sound absorbing materials are used to reduce sound levels, then the sound power level is reduced, but the coverage area and protection height decrease

Engineering Contradiction:

Improvesound power levelVSAvoidcoverage area

Core Design Contradiction:

Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

The patent extracts the sound reduction function from the nozzle itself by using downstream acoustic treatment elements such as acoustic panels or barriers positioned in the gas discharge path. This allows the nozzle to maintain its full coverage area and protection height while the separate acoustic elements reduce sound power levels to below 130 dB.

Inventive Principle:

Principle #2Taking out (Extraction)

3Object-affected harmful factors

If the flow rate is significantly reduced to lower sound levels, then the sound power level decreases, but the pressure drop increases and fire suppression effectiveness is compromised

Engineering Contradiction:

Improvesound power levelVSAvoidpressure drop

Core Design Contradiction:

Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

By segmenting the flow into multiple outlet holes, the patent reduces the velocity head losses associated with a single high-velocity jet. The multiple lower-velocity streams experience reduced turbulence and shock wave formation, thereby reducing pressure drop while maintaining the total flow rate necessary for effective fire suppression and keeping sound power levels below 130 dB.

Inventive Principle:

Principle #1Segmentation

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 nozzles effectively reduce sound levels to protect sensitive equipment while maintaining the required coverage area and height, allowing for retrofitting without substantial system modifications, ensuring rapid inert gas discharge for fire suppression.

Implementation Method 1

a pressure reducing device upstream to minimize sound power while maintaining effective gas discharge

Methodology Applied

Scientific EffectPressure reduction: Pressure Drop

Implementation Method 2

balance gas flow through multiple outlet holes and use a pressure reducing device upstream to minimize sound power

Methodology Applied

Scientific EffectGas flow balance: Turbulence

Data Source

PatentUS11389678B2Low pressure drop acoustic suppressor nozzle for inert gas discharge system

Publication Date: 2022.07.19 TYCO FIRE PRODUCTS LP

AI summary

A fire suppression system includes an inert gas source to supply inert gas to an enclosure via distribution piping. The system includes a fire suppression nozzle that is installed in the enclosure. The nozzle includes an inlet that connects to the distribution piping and includes a plurality of outlet holes. During discharge of the inert gas, the sound power level from, the nozzle is no greater than 125 dB for a frequency range from 500 to 10,000 Hz for a coverage area up to 32 ft.×32 ft. in compliance with UL 2127. The nozzles disclosed herein are configured such that gas exiting a plurality of outlet holes is balanced.