Double-Jacket Fire Hose Laminate for High-Heat Resistance
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Solution Overview
Problem
Current attack hoses fail to achieve the highest possible thermal performance while meeting NFPA 1961-2019 standards, requiring a solution that balances thermal resistance, flexibility, and cost-effectiveness for use in tight fire spaces.
Innovation Solution
A hose construction featuring a woven outer jacket of continuous para- and meta-aramid fibers with an inner jacket made of extruded nitrile rubber, where the rubber is extruded through the weave to form a laminate structure, and optionally includes a heat-reflective film between the jackets for enhanced thermal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional fire hose materials and constructions are used, then cost and ease of manufacture are maintained, but thermal performance and resistance to radiative and convective heat are insufficient
Solution Approach 1:
The hose employs a composite construction combining an inner jacket of para-aramid fibers, an intermediate layer of meta-aramid fibers, and an outer jacket of para-aramid fibers. This multi-layer composite structure provides superior thermal performance and resistance to radiative and convective heat while maintaining manufacturability through standardized weaving and assembly processes
Solution Approach 2:
The hose construction features nested layers where the inner para-aramid jacket is surrounded by the meta-aramid intermediate layer, which is in turn surrounded by the outer para-aramid jacket. This nested structure allows each layer to contribute specific thermal properties, with the meta-aramid layer providing resistance to radiative heat and the para-aramid layers providing structural integrity and resistance to convective heat
2Object-affected harmful factors
If thicker or more layers are added to improve thermal resistance, then thermal performance improves, but weight per unit length and flexibility deteriorate
Solution Approach 1:
The hose assigns different functional qualities to different layers: the inner para-aramid jacket provides structural strength and resistance to convective heat, the intermediate meta-aramid layer specifically resists radiative heat with its lower thermal conductivity, and the outer para-aramid jacket provides additional structural support. This localized functional distribution achieves optimal thermal protection without excessive weight
Solution Approach 2:
The combination of para-aramid and meta-aramid fibers in a three-layer composite structure provides superior thermal resistance per unit weight compared to single-material constructions. The meta-aramid layer's lower thermal conductivity provides thermal insulation, while the para-aramid layers provide structural strength, achieving high thermal performance with minimal weight increase
3Stress or pressure
If higher operating pressures are sustained, then fire fighting effectiveness improves, but structural integrity and resistance to bursting become more challenging
Solution Approach 1:
The three-layer composite construction with para-aramid and meta-aramid fibers provides enhanced strength-to-weight ratio and resistance to bursting at high operating pressures. The interlocking weave patterns and material properties of each layer work together to distribute stress uniformly, preventing failure under pressures of 300 psi or higher
Solution Approach 2:
The hose is designed with pre-tensioned aramid fiber layers and a pre-assembled three-layer structure that is tested and certified to withstand proof pressures significantly higher than operating pressures. This preliminary structural preparation ensures the hose can sustain high operating pressures without deformation or failure during fire fighting operations
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 hose demonstrates superior thermal performance, lasting significantly longer than conventional hoses during radiant and conductive heat testing, while maintaining flexibility and structural integrity, thus meeting the stringent requirements of NFPA 1961-2019.
Implementation Method 1
a heat-reflective film may be interposed between the inner and outer jackets, so as to further enhance the thermal performance of the hose
Implementation Method 2
nitrile rubber is simultaneously pushed through both the inner and outer surfaces of a nylon and/or polyester inner jacket
Data Source
AI summary
An attack fire hose capable of withstanding radiant and convective heating without leakage or degradation of performance for significant periods of time is disclosed. The hose includes a woven aramid blend of fibers in the outer jacket, and a nitrile rubber layer is extruded through the weave of an inner nylon/polyester jacket that is fitted within the woven outer jacket. The resultant hose retains a double jacketed construction with exceptional thermal performance.