Underground Conduit Flow Restrictor for Fire and Explosion Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Underground manhole systems are prone to fires and explosions due to the inability to effectively inspect and manage cables within connections, leading to safety risks and damage from flammable gases, as existing duct plugs fail to maintain a gas-tight seal and can exacerbate conditions for explosions.
Innovation Solution
A duct flow restrictor system that includes an annular restriction device and a concentration member to control airflow, allowing fresh and contaminated air to flow while limiting oxygen supply to potential fires, and a perturbation detector to identify the source of fires by concentrating and amplifying gas perturbations, enabling targeted intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If duct plugs are used to seal connections, then gas-tight sealing is improved, but explosion risk increases due to pressure buildup
Solution Approach 1:
The connection is divided into multiple sealed zones by installing duct plugs at both ends and intermediate points, creating segmented compartments that limit fire propagation while allowing pressure relief at designated vent points
Solution Approach 2:
A pressure relief valve or vent mechanism is introduced as an intermediary component between the sealed connection and the vault, allowing controlled pressure release to prevent explosion while maintaining the gas-tight seal of the duct plug
2Object-affected harmful factors
If duct plugs are used to prevent gas flow, then fire spread is limited, but oxygen starvation causes incomplete combustion and toxic gas accumulation
Solution Approach 1:
The duct plug design incorporates localized features such as micro-ventilation channels or selective permeability zones that allow controlled oxygen diffusion to sustain complete combustion while blocking the bulk flow of flammable gases
Solution Approach 2:
A catalytic converter or oxidation catalyst is introduced as an intermediary component within the duct plug structure that promotes complete combustion of any accumulated gases, converting toxic products into less harmful substances before they enter the vault
3Reliability
If cables are insulated to prevent tracking, then electrical safety is improved, but heat dissipation is reduced leading to higher operating temperatures
Solution Approach 1:
The cable insulation uses composite material structures with multiple layers having different thermal and electrical properties, such as cross-linked polyethylene outer layer for electrical protection combined with thermally conductive inner layers or heat dissipation additives that facilitate heat transfer away from the conductor
4Object-generated harmful factors
If ventilation is increased to remove toxic gases, then air quality is improved, but fire risk increases due to additional oxygen supply
Solution Approach 1:
The ventilation system uses localized exhaust points positioned near the vault ceiling or at strategic locations where toxic gases naturally accumulate, creating targeted air exchange zones that remove contaminants without introducing oxygen throughout the entire connection space
Solution Approach 2:
The ventilation system introduces inert gas (such as nitrogen or carbon dioxide) to displace oxygen in localized zones, creating an inert atmosphere that suppresses fire risk while still allowing toxic gases to be removed through controlled pathways
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 duct flow restrictor system reduces the risk of large fires and explosions by controlling airflow and identifying fire sources, preventing oxygen supply to sustain significant combustion, while the perturbation detector aids in pinpointing faulty cables, thereby minimizing damage and ensuring safety by preventing gas leakage into vaults or private premises.
Implementation Method 1
an annular restriction device to restrict flow through the connection
Implementation Method 2
a concentration member that allows fresh and contaminated air to flow through the connection while concentrating and amplifying perturbations
Implementation Method 3
restricting the flow of gas (e.g., oxygen) to the fire (430)
Data Source
AI summary
A flow restrictor for installation in a connection having a terminus opening into an underground vault. The flow restrictor includes an annular restriction device and a concentration member. The annular restriction device is configured to be installed in the annulus near the terminus opening and to restrict a flow of one or more gases through the annulus of the connection. The concentration member is configured to concentrate the flow and includes a through-channel configured to allow the concentrated flow to flow between the underground vault and the annulus.