Fireproof Hose Composition for Zero-Flow Flame Resistance

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Solution Overview

Problem

Existing aerospace fluid conveyance products, such as hoses, face challenges in meeting stringent fireproofing requirements, particularly under zero flow conditions, as they tend to degrade during exposure to fire, fail to consistently meet AS1055 and TSO fire performance standards, and external fire sleeves increase weight and complexity, making them difficult to clamp in aircraft.

Innovation Solution

A fireproof hose design featuring multiple layers, including an inner PTFE tube, metallic reinforcement, and an outer thermal insulation layer composed of silicone rubber, expanded graphite, and zinc borate, which provides enhanced fire resistance and meets AS1055 and TSO requirements without the need for an external fire sleeve, offering a smoother outer diameter and reduced weight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If external fire sleeves are used to meet fireproofing requirements, then fire resistance is improved, but weight increases and device complexity increases

Engineering Contradiction:

Improvefire resistanceVSAvoidhose weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent combines the fireproofing function with the hose structure itself by integrating a thermal insulation layer containing fire retardant materials (zinc borate and expandable graphite) directly into the hose wall composition. This merges the protective sleeve function with the hose body, eliminating the need for separate external fire sleeves and thereby reducing overall weight while maintaining fire resistance.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent employs composite materials in the thermal insulation layer, specifically combining silicone rubber base polymer with fire retardant additives (zinc borate and expandable graphite). This composite material approach provides both the structural integrity needed for hose function and the fireproofing properties required to meet AS1055 and TSO standards, replacing the need for separate fire protective layers.

Inventive Principle:

Principle #40Composite materials

2Reliability

If external fire sleeves are used to meet fireproofing requirements, then fire resistance is improved, but device complexity increases and ease of operation deteriorates

Engineering Contradiction:

Improvefire resistanceVSAvoidclamping difficulty

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

By integrating the fireproofing function directly into the hose wall through the thermal insulation layer, the patent eliminates the separate external fire sleeve component. This integration results in a smoother outer surface without wrinkles or irregularities, making the hose easier to clamp and install in aircraft applications while maintaining the required fire resistance.

Inventive Principle:

Principle #5Merging (Combining)

3Ease of manufacture

If traditional hose compositions are used, then ease of manufacture is maintained, but fire resistance deteriorates under zero flow conditions

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidfire resistance under zero flow

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent modifies the hose composition by incorporating a thermal insulation layer with specific fire retardant materials (zinc borate and expandable graphite) dispersed in a silicone rubber matrix. This composite material approach maintains compatibility with existing manufacturing processes while providing the enhanced fire resistance required to meet AS1055 and TSO standards under zero flow conditions.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the chemical composition parameters of the thermal insulation layer by specifying particular fire retardant additives (zinc borate and expandable graphite) at controlled concentrations within the silicone rubber matrix. These parameter changes enable the material to achieve the required fire resistance performance while remaining manufacturable using standard hose production techniques.

Inventive Principle:

Principle #35Parameter changes

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 effectively withstands direct flames for 5 to 15 minutes under zero flow conditions, passes flame resistance tests, and maintains structural integrity, achieving a 10-15% weight reduction and envelope reduction compared to existing solutions, while ensuring ease of clamping and compatibility with aerospace fluids.

Implementation Method 1

expandable graphite

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

expandable graphite and zinc borate act as flame retardant

Methodology Applied

Scientific EffectChar formation: Pyrolysis

Implementation Method 3

thermal insulation layer composed of silicone rubber, expanded graphite, and zinc borate

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS11536400B2Zero flow fireproof hose utilizing zinc borate and expandable graphite additives

Publication Date: 2022.12.27 EATON INTELLIGENT POWER LTD

AI summary

A hose is provided capable of meeting fireproof requirements per AS1055 under no flow condition. The hose has multiple layers of fire protection comprising a silicone rubber layer impregnated with additives including zinc borate and expandable graphite.