Split Firestopping Bushing for Gypsum Board Cable Penetrations
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Solution Overview
Problem
Existing methods for firestopping around cables and wires in walls are labor-intensive, costly, and lack a clean appearance, as they require skilled technicians and are not suitable for small cables or cables already installed, and they struggle to provide effective sealing in gypsum board walls.
Innovation Solution
A split firestopping bushing made of thermoplastic material, consisting of two identical half sections with barbs for secure attachment to the wallboard, featuring intumescent foam sealing sections to prevent smoke and flames, allowing for easy installation around cables or wires before or after they pass through the wall.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mastic materials are used for firestopping around cables, then firestopping function is achieved, but labor cost and installation time increase significantly
Solution Approach 1:
The firestopping system is segmented into a reusable mechanical bushing component and a separate firestop sealant. The bushing is pre-installed in the wall opening and can be reused across multiple cable installations, while the sealant is applied separately to achieve firestopping. This segmentation allows the mechanical structure to be installed once and reused, eliminating the need for skilled labor to apply sealant around each individual cable.
Solution Approach 2:
The mechanical bushing is installed in advance before cables are routed through the wall. This preliminary installation creates a pre-formed opening and structural support that simplifies subsequent cable installation and firestopping. The bushing is positioned and secured to the wallboard beforehand, allowing cables to be simply inserted through the pre-prepared opening without requiring complex on-site assembly.
2Reliability
If mastic materials are used for firestopping, then sealing is achieved, but the appearance quality becomes highly dependent on technician skill
Solution Approach 1:
The system separates the mechanical support function (bushing) from the firestopping sealant application. The bushing provides a uniform, pre-formed structure with consistent dimensions and appearance that is not dependent on application skill. The sealant is contained within the bushing structure, ensuring uniform application and eliminating variability in appearance quality based on technician skill level.
3Strength
If rubber plugs or framing constructions are used, then mechanical support is provided, but they cannot be installed in gypsum board walls due to insufficient structural strength
Solution Approach 1:
The bushing is designed with localized reinforcement features including barbs that engage with the gypsum board and a flared outer diameter that distributes mechanical loads. The barbs provide anchoring strength by mechanically interlocking with the gypsum board material, while the flared shape distributes expansion forces across a larger area. This localized quality enhancement allows the bushing to provide rubber-plug-level mechanical support while being compatible with the limited structural strength of gypsum board walls.
4Reliability
If sealants are used to firestop around cables, then firestopping is achieved, but cables become adhered to each other and to the wallboard making future changes difficult
Solution Approach 1:
The system divides the firestopping function into two separate components: the mechanical bushing that maintains cable separation and physical space, and the firestop sealant that provides fire resistance. The bushing structure prevents cables from adhering to each other or the wallboard by maintaining physical separation and providing a non-adhesive mechanical barrier. This segmentation allows cables to remain movable and reconfigurable while still achieving effective firestopping through the separate sealant application.
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 bushing significantly reduces labor costs, provides a clean appearance, and effectively seals against smoke and flames, even in gypsum board walls, allowing for easy installation and adjustment of cable configurations without adhering cables to each other or the wallboard.
Implementation Method 1
featuring intumescent foam sealing sections to prevent smoke and flames
Data Source
AI summary
A relatively inexpensive bushing easily installed extending through walls, particularly, gypsum board membrane walls for providing firestopping around a limited number of linear penetrating members such as cables or wires. This grommet construction includes first and second half sections for facilitating attachment around cables more easily. A split internal seal preferably of resilient foam material is positioned within a split mechanical shell which facilitates placing of the bushing around penetrating members prior to placement thereof through walls or after positioned thereof penetrating through a panel such as wallboard. A split mechanical shell with a two-piece foam insert retained within a bore extending therethrough can be formed as two separable half cylindrical shells. Barbs are included on the outer portion of the shell to facilitate mounting thereof. The foam firestopping seal portion can be intumescent.