Passive Intumescent Fire Damper for Small Ductwork Airflow
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Solution Overview
Problem
Existing fire dampers are complex, expensive, and unsuitable for small ductwork applications due to obstructions in the air stream, requiring access doors and periodic testing, which can lead to blockages and impaired operation.
Innovation Solution
A passive intumescent fire damper with a metal ductwork housing, a meltable plastic liner, and a metal-intumescent laminate assembly encased in a sheet metal fitting, where the liner melts to expose the intumescent material out of the air stream, expanding to close the duct passage without obstructions, and heat shrink bands accelerate this process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fire dampers with access doors and mechanical components are used, then fire containment is achieved, but device complexity and maintenance requirements increase
Solution Approach 1:
The invention removes the mechanical damper components and access door mechanisms from the ductwork, extracting only the essential fire containment function. The passive intumescent material performs the fire blocking without requiring mechanical actuators, sensors, or access panels, thereby eliminating the associated complexity and maintenance needs while maintaining fire containment reliability
Solution Approach 2:
The fire damper system is designed to be self-activating through the passive intumescent material that automatically expands when exposed to fire temperatures. This self-service mechanism eliminates the need for external power sources, control systems, or manual intervention, reducing device complexity while ensuring reliable fire containment activation
2Reliability
If fire dampers with obstructions in air stream are installed, then fire containment is provided, but material buildup and blockage hazards occur
Solution Approach 1:
The invention extracts the fire containment function from the air stream path by positioning the passive intumescent material on the exterior surface of the ductwork. This eliminates obstructions within the air stream, preventing material buildup and blockage hazards while maintaining effective fire containment through the intumescent expansion on the duct exterior
Solution Approach 2:
The passive intumescent material is applied as a thin coating or wrap on the ductwork exterior, creating a flexible fire barrier that does not interfere with air flow through the duct. This thin film approach maintains unobstructed air stream while providing effective fire containment when the intumescent expands
3Reliability
If conventional fire dampers requiring access doors are used, then fire containment is achieved, but ease of installation and maintenance deteriorate
Solution Approach 1:
The invention removes the access door requirement by applying the passive intumescent material directly to the ductwork exterior or interior surfaces during installation. This eliminates the need for future access doors and periodic manual testing, significantly improving ease of installation while maintaining fire containment through the passive material's automatic activation
Solution Approach 2:
The passive intumescent fire damper requires no manual operation, testing, or maintenance after installation. The system serves itself by automatically activating through thermal exposure, eliminating the need for access doors for periodic inspection or testing, thereby dramatically improving ease of operation and reducing maintenance requirements
4Adaptability or versatility
If fire dampers suitable for small ductwork are designed, then adaptability to small ducts is improved, but fire containment effectiveness may be compromised
Solution Approach 1:
The passive intumescent material is applied specifically to the critical fire exposure surfaces of the ductwork in proportionally appropriate amounts. This localized application ensures effective fire containment for small duct dimensions without requiring oversized components, maintaining both adaptability to small ductwork and reliable fire containment performance
Solution Approach 2:
The intumescent material properties and application thickness are optimized for small ductwork dimensions. The material's expansion characteristics and thermal response are tailored to provide adequate fire containment in smaller duct cross-sections, ensuring both adaptability to various duct sizes and maintained fire containment effectiveness
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 simple, inexpensive, and easy-to-install fire damper with minimal friction loss and no need for access doors, suitable for small ductwork like kitchen and bathroom ventilation, ensuring effective fire containment without material buildup or complex maintenance.
Implementation Method 1
a liner of plastic or other material which will melt at a certain temperature
Implementation Method 2
The heat shrink tubing is then exposed to heat and as it shrinks it pulls the metal of the laminate assembly in radially
Implementation Method 3
The intumescent material is then exposed to the inside of the ductwork and when exposed to the heat will expand and close off the duct passage
Implementation Method 4
The metal of the laminate assembly accelerates this process by conduction and ensures that the intumescent continues expansion
Data Source
AI summary
There is disclosed a passive intumescent fire damper having a metal housing, an inner meltable liner and having a metal and intumescent laminate assembly surrounding the inner liner.