PVC Fire Stop Fitting Using Early Foaming Bore Closure
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Solution Overview
Problem
Existing fire stop solutions for preventing fire propagation through wall openings are costly and complex due to the need for sophisticated compositions and molding techniques to ensure effective expansion of intumescent materials before charring occurs, which is not adequately addressed by prior art.
Innovation Solution
A thermoplastic fire stop fitting made from PVC with a blowing agent that releases gas at a predetermined temperature, allowing the resin to foam and expand before charring, effectively closing off pipe openings without the need for additional intumescent materials or complex molding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sophisticated compositions and complex molding techniques are used to ensure effective expansion of intumescent materials before charring, then fire stop reliability is improved, but manufacturing cost and device complexity increase
Solution Approach 1:
The patent changes the temperature parameter relationship between blowing agent activation and material charring. By selecting a blowing agent with lower decomposition temperature than the PVC charring temperature, the expansion occurs at a lower temperature threshold, ensuring reliable fire stop function before the material chars and loses structural integrity.
Solution Approach 2:
The patent utilizes the phase transition of the blowing agent (solid to gas) at a predetermined temperature to drive the expansion of the fire stop material. This phase transition creates internal gas pressure that forces the material to expand and close off the opening, providing reliable fire containment through a thermally-activated mechanism.
2Reliability
If sophisticated compositions and complex molding techniques are used to ensure effective expansion of intumescent materials before charring, then fire stop reliability is improved, but manufacturing cost increases
Solution Approach 1:
The patent simplifies manufacturing by changing the temperature parameter relationship - using a blowing agent that activates at a lower temperature than the PVC charring point. This eliminates the need for complex multi-step molding processes and sophisticated compositions, as the standard molding process itself can be used to create the final product geometry, and the fire stop function is achieved through the thermal response of the materials.
Solution Approach 2:
The patent employs conventional, readily available materials (PVC and standard blowing agents) rather than expensive specialized intumescent compositions. The fire stop relies on the inherent thermal properties of these common materials rather than costly proprietary formulations, significantly reducing material and manufacturing costs while maintaining reliability.
3Object-affected harmful factors
If intumescent material expands strongly enough to collapse the PVC pipe, then fire propagation is blocked, but the expansion must occur after the pipe has begun to char which reduces expandability
Solution Approach 1:
The patent fundamentally changes the temperature parameter sequence by selecting a blowing agent with a lower decomposition temperature than the PVC charring temperature. This ensures the expansion process begins at a lower temperature threshold, when the PVC is still relatively stable and can be effectively deformed and collapsed by the expanding material, rather than attempting to expand after the PVC has already charred and become rigid.
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 provides a cost-effective and efficient means to block fire propagation by expanding to close off pipe openings before charring occurs, using a simple combination of PVC and a temperature-activated blowing agent, ensuring effective fire containment without the complexity and cost of prior solutions.
Implementation Method 1
a blowing agent which releases gas at a predetermined temperature
Implementation Method 2
allowing the resin to foam and expand before charring
Implementation Method 3
the resin softens as the resin is heated until the resin is soft enough for the released gas to expand the plastic to form a foam
Implementation Method 4
the resin softens as the resin is heated until the resin is soft enough for the released gas to expand the plastic
Implementation Method 5
before a char is formed on said expanded body by said fire
Data Source
AI summary
A fire stop device having a body having a through bore and the body being sized and shaped to be positioned within an opening in a wall. the body is made from a moldable a thermoplastic resin having a blowing agent suspended therein. The blowing agent has a predetermined gas release temperature and the thermoplastic resin has a melting temperature above the predetermined gas release temperature of the blowing agent; wherein when exposed to a fire the blowing agent first begins to release gas and the resin softens as the resin is heated until the resin is soft enough for the released gas to expand the plastic to form a foam to close said through bore before a char is formed on said expanded body by said fire. A method of forming a fitting having the blowing agent suspended therein is also provided.