Flame-Resistant End Cap for Heat Shrink Trace Heating Cables
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Solution Overview
Problem
Existing heat shrink kits for electrical systems, particularly tee connection and end seal kits, face limitations in flammability protection due to the pinched portion of heat shrink tubing, which can ignite and burn longer than allowed in flammability tests, posing a risk during vertical flame tests.
Innovation Solution
A splice kit and end cap configuration using a flame-resistant material with a tubing portion and end portion designed to prevent flames from reaching the heat shrink tubing, eliminating the need for a pinched seal and enhancing flammability protection by using a friction fit or adhesive layers for secure installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat shrink tubing is used to seal and insulate cable connections, then moisture protection and electrical insulation are improved, but flammability resistance deteriorates due to the pinched portion igniting and burning
Solution Approach 1:
The heat shrink assembly is segmented into multiple functional components: a base heat shrink tubing for moisture protection and electrical insulation, and a separate flame-resistant cap that prevents flame propagation. This segmentation allows each component to optimize its specific function without compromise.
Solution Approach 2:
The flame-resistant cap acts as an intermediary barrier between the external flame source and the heat shrink tubing. It intercepts and blocks flame before it can reach the polymeric tubing, preventing ignition while allowing the tubing to maintain its moisture sealing function.
2Ease of operation
If the heat shrink tubing is crimped to create a sealed or pinched portion, then installation security is improved, but flammability protection deteriorates at the sealed area
Solution Approach 1:
The sealing and flame protection functions are extracted from the heat shrink tubing itself and placed into a separate dedicated flame-resistant cap. This removes the conflicting requirements from a single component, allowing the tubing to focus on sealing while the cap handles flame resistance.
Solution Approach 2:
Instead of making the heat shrink tubing itself flame-resistant (which would compromise its sealing properties), the solution inverts the approach by placing a flame-resistant component over the tubing to provide protection from the outside in.
3Object-affected harmful factors
If flame retardants are added to heat shrink tubing, then flammability resistance is improved, but the tubing still ignites under vertical flame test conditions
Solution Approach 1:
The heat shrink assembly uses composite material construction combining heat shrink tubing (for sealing) with a flame-resistant cap material that has superior fire resistance properties. This composite approach achieves flame test compliance that neither material could achieve alone.
Solution Approach 2:
The flame-resistant cap provides beforehand cushioning by creating a protective barrier that absorbs and blocks thermal energy from reaching the heat shrink tubing during flame exposure, preventing the tubing from reaching its ignition temperature even when flame retardants are present.
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 solution allows heat shrink kits to pass vertical flame tests by preventing excessive damage and ensuring the heat shrink tubing does not split, thereby improving flammability performance and reducing the risk of ignition during testing.
Implementation Method 1
heat shrink tubing, which can provide a barrier against moisture as well as electrical insulation
Implementation Method 2
Heat shrink tubing can include an adhesive lining. Adhesive lined heat shrink tubing is ubiquitous, and is an effective moisture sealer and electrical insulator.
Data Source
AI summary
An end cap for a heat shrink kit having a heat shrink tubing, wherein the end cap includes a tubing portion sized to be inserted into the heat shrink tubing and an end portion configured to prevent at least a portion of a flame from reaching the heat shrink tubing.