Multi-layer Polyethylene Polyamide Seal for Fire Extinguisher
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing fire extinguishers face issues with the seal tearing due to additive settling, leading to unwanted pressure increases and potential clogging, and fail to maintain tightness across a wide temperature range, particularly at 60°C.
Innovation Solution
A fire extinguisher with a seal comprising alternating layers of polyethylene and polyamide, providing sufficient strength to resist settling and tear evenly under pressure, ensuring effective mixing without water hammer and maintaining sealing integrity across varying temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the lid is made strong to resist settling, then the lid does not tear during transport, but it may tear off completely during pressurization or cause water hammer
Solution Approach 1:
The lid is segmented into multiple layers with different material properties. The polyethylene layers provide strength and sealing, while the polyamide layers provide controlled tear propagation. This segmentation allows the lid to resist settling forces while enabling controlled tearing during pressurization without complete detachment or water hammer effect.
Solution Approach 2:
The lid uses a composite structure alternating between polyethylene and polyamide layers. Polyethylene provides mechanical strength and sealing properties, while polyamide provides controlled tear characteristics. This composite material approach resolves the contradiction by combining materials with complementary properties to achieve both strength and controlled tearing behavior.
2Ease of operation
If the lid is made thin to allow easy tearing, then the lid tears easily under pressure, but it may tear due to settling during transport
Solution Approach 1:
The lid is divided into multiple thin layers rather than one thick layer. Each layer is thin enough to allow easy tearing, but the combined structure provides sufficient strength to resist settling. The segmentation enables controlled tear propagation through the layers during pressurization while maintaining integrity during transport.
Solution Approach 2:
The alternating polyethylene and polyamide layers create a composite structure where each material contributes different properties. Polyethylene layers provide strength and sealing, while polyamide layers facilitate controlled tearing. This composite approach allows the lid to be thin overall while maintaining sufficient strength through the combined layers.
3Reliability
If a two-layer polyethylene/aluminum lid is used, then the lid provides good sealing, but leaks appear at 60°C
Solution Approach 1:
The invention changes the material parameters by replacing aluminum with polyamide in the lid structure. Polyamide has different thermal expansion and sealing properties compared to aluminum, maintaining sealing effectiveness at elevated temperatures up to 60°C. This parameter change in material selection resolves the thermal stability issue while preserving sealing tightness.
Solution Approach 2:
The alternating polyethylene and polyamide layers create a composite structure with improved thermal performance. The polyamide layers provide thermal stability and maintain sealing properties at 60°C, while polyethylene layers provide the necessary mechanical strength and sealing. This composite approach resolves the temperature-related leaking issue.
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 multi-layer seal design prevents seal tearing during use, avoids clogging, and maintains tightness across a wide temperature range, ensuring reliable operation and effective mixing of additives with the extinguishing agent.
Implementation Method 1
a seal capable of tearing under the effect of a pressure difference
Implementation Method 2
a first layer of polyethylene welded to said container
Data Source
Figure 1
AI summary
The extinguisher (1) has a reservoir (2) containing a to-be-sprayed product (3) e.g. water, and a container (8) for containing an additive (9) to be mixed with the product. The container is closed by a cover (7) that is tearable under the effect of pressure difference. The cover comprises a polyethylene layer welded to the container, a polyamide layer, another polyethylene layer, and another polyamide layer in a successive manner. The container is made of high density polyethylene.