Severable Flexible Ventilation Duct for Fire Safety
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Solution Overview
Problem
Flexible ventilation ducts used in underground tunnels are prone to burning, posing a significant fire safety risk for operators and equipment, and existing fireproof options are costly due to the potential length of ventilation systems exceeding several kilometers.
Innovation Solution
A severable flexible ventilation duct system featuring interconnected pipe sections with a cable severable connection member, including a disjunction wire that allows for quick separation of pipe sections, preventing fire spread and enabling smoke extraction, utilizing non-flammable materials like aramid fibers or steel for the disjunction wire.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fireproof flexible pipes are used, then fire safety is improved, but cost increases significantly
Solution Approach 1:
The ventilation duct is divided into multiple separable sections connected by coupling members. In case of fire, the duct can be segmented by separating the coupling members, preventing fire propagation along the entire duct length. This allows using standard non-fireproof flexible pipe material while achieving fire safety through modular separation capability.
Solution Approach 2:
The fire safety function is extracted from the pipe material itself and implemented through a separate mechanism: the separable coupling system. Instead of making the entire duct fireproof, the design extracts the safety requirement and satisfies it through removable connection points that can isolate fire zones.
2Stability of the object's composition
If the ventilation duct is made as a single continuous piece, then ventilation continuity is maintained, but fire spread risk increases
Solution Approach 1:
The continuous ventilation duct is segmented into multiple sections that can be separated. The coupling members provide connection points that maintain continuity during normal operation but enable separation when fire risk is detected, thus resolving the contradiction between continuity and fire spread prevention.
Solution Approach 2:
The ventilation duct transitions from a static continuous structure to a dynamic modular system. The coupling members can change state from connected to separated based on operational conditions, allowing the duct to adapt between maintaining continuity and preventing fire spread.
3Reliability
If the disjunction wire has high breaking strength, then separation reliability is improved, but ease of operation deteriorates
Solution Approach 1:
The coupling member uses different material properties in different locations: the housing provides structural strength while the disjunction wire provides controlled weakness. The wire's localized lower strength compared to the housing allows easy pulling operation, while the overall assembly maintains reliability through the strong housing structure.
Solution Approach 2:
The disjunction wire is designed with specific mechanical parameters (breaking strength between 50-200 N) that differ from the housing material. This parameter differentiation enables the wire to be easily pulled for separation while the housing maintains structural integrity, resolving the contradiction between separation ease and reliability.
Data Source
Figure 1~3
Figure 2~4
AI summary
Flexible disconnectable ventilation duct (1) comprising a first and a second section (2, 3) of pipe connected together and a connecting member (8) with cable disconnection, the connecting member comprising a first part (9) having a closed contour, connected to the first section, a second part (10) having a closed contour, connected to the second section, and a separable closure system (8a), the connecting member comprising a disconnection wire (12) of the first and second parts by opening the closure system, the wire being disposed partly inside and near the first and second parts, the wire comprising a portion connected to the second part and a free end projecting out of the first and second parts, so that an operator separates the first and second parts of the connecting member thus causing a separation of the first and second sections of pipe.