Fire-Resistant Coaxial Cable Ceramifiable Dielectric
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Solution Overview
Problem
Current coaxial communication cables fail to meet fire survivability standards, as they melt or degrade at high temperatures, necessitating waivers or extensive shielding in buildings, which is not feasible in all scenarios.
Innovation Solution
Development of fire-resistant coaxial cables with ceramifiable silicone rubber or ceramic fiber dielectrics between conductors, which convert to a brittle, porous ceramic structure at high temperatures, maintaining structural integrity and spacing, and are wrapped with a low smoke zero halogen jacket to prevent shorting and ensure signal passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polymer or foam dielectrics are used in coaxial cables, then the cables are flexible and easy to manufacture, but they melt or degrade at high temperatures and fail to meet fire survivability standards
Solution Approach 1:
The dielectric material undergoes a parameter change from organic polymer/foam to inorganic ceramic through a phase transition process. The cable is designed to transform its material properties in situ when exposed to fire temperatures, converting the dielectric from a flexible polymer state to a rigid ceramic state that maintains structural integrity and electrical performance at high temperatures up to 1010°C
Solution Approach 2:
The patent employs composite material construction by combining ceramic dielectric material with metal conductors and protective jacketing. This composite structure integrates the high-temperature stability of ceramics with the electrical conductivity of metals and the protective functions of specialized jacketing, creating a cable system that meets fire survivability standards while maintaining manufacturability
2Reliability
If building codes require two-hour burn time at 1010°C, then communication reliability during emergencies is improved, but conventional coaxial cables cannot meet this standard without extensive shielding or waivers
Solution Approach 1:
The cable utilizes phase transition of the dielectric material from polymer to ceramic form when exposed to fire temperatures. This phase change enables the cable to automatically achieve fire resistance properties without requiring external shielding or complex protective structures, maintaining communication functionality throughout the two-hour burn period required by building codes
Solution Approach 2:
The cable structure is designed to self-protect during fire exposure through the in-situ transformation of the dielectric material. The material automatically undergoes ceramification when heated, creating a protective ceramic barrier that maintains electrical insulation and structural integrity without requiring external protective measures or increasing device complexity
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 cables can withstand temperatures up to 1010°C for two hours without failing, meeting building codes without the need for additional shielding, ensuring continuous communication during emergencies.
Implementation Method 1
the ceramifiable dielectric maintains its structural integrity by ceramifying. That is, the resilient dielectric turns into a brittle, porous ceramic structure
Implementation Method 2
When subjected to temperatures exceeding 1010° C. (1850° F.), the ceramifiable dielectric maintains its structural integrity by ceramifying
Data Source
AI summary
A fire-resistant coaxial cable is described in which the dielectric between the central conductor and outer coaxial conductor can ceramify under high heat. The dielectric is composed of a ceramifiable silicone rubber, such as that having a polysiloxane matrix with inorganic flux and refractory particles. An outer wrap of ceramic fiber yarn surrounds the outer conductor and continues to insulate it from the outside if a low smoke zero halogen jacket burns away. Embodiments include those with durable corrugated outer conductors or flexible braided outer conductors. Methods of testing and installation are described.