Layered Firestop Seal Structure for Controlled Intumescent Expansion

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Solution Overview

Problem

Conventional fire protection elements for sealing openings in building components face issues such as inefficient expansion of physically active blowing agents, leading to partial utilization of intumescence potential, increased thermal conductivity, and material wastage, particularly in larger openings and thick-walled pipes, which complicates installation and is ecologically and economically disadvantageous.

Innovation Solution

A layered fire protection element comprising fire-resistant layers with embedded or surface-applied physically active blowing agents and a semi-rigid functional layer that distributes expansion pressure and maintains flexibility, ensuring complete expansion and improved sealing without excessive material usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If large quantities of physically active blowing agents are used to ensure reliable seal in larger openings and thick-walled pipes, then sealing capability is improved, but material wastage increases and installation becomes more difficult

Engineering Contradiction:
Improvesealing capabilityVSAvoidmaterial wastage
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The patent changes the physical state and distribution parameters of the blowing agent by using a layered structure. The blowing agent is concentrated in specific layers rather than uniformly distributed, which optimizes its expansion effectiveness and reduces the total quantity needed while maintaining reliable sealing capability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite layered structure combining different materials with specific functions: a carrier material layer, a blowing agent layer, and a semi-rigid functional layer. This composite structure allows each layer to contribute optimally to the sealing function, reducing overall material usage while improving reliability.

Inventive Principle:
Principle #40Composite materials

2Reliability

If large quantities of physically active blowing agents are used to ensure reliable seal in larger openings and thick-walled pipes, then sealing capability is improved, but installation complexity increases

Engineering Contradiction:
Improvesealing capabilityVSAvoidinstallation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The layered composite structure integrates multiple functions into distinct layers, making the overall system more manageable. The semi-rigid functional layer provides structural support that facilitates installation, while the blowing agent layer is pre-positioned for optimal performance, reducing on-site complexity.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The fire protection element is segmented into functional layers with the blowing agent confined to specific zones. This segmentation allows for more efficient material distribution and reduces the overall complexity of handling and installation compared to a homogeneous structure requiring uniform material application.

Inventive Principle:
Principle #1Segmentation

3Force

If physically active blowing agents expand in all three spatial directions, then expansion pressure is generated, but mutual impediment occurs causing negative intumescence

Engineering Contradiction:
Improveexpansion pressureVSAvoidintumescence potential
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The patent transitions from three-dimensional random expansion to controlled two-dimensional expansion by positioning the blowing agent in a layered structure. The semi-rigid functional layer acts as a constraint that directs expansion primarily in the plane of the layer, reducing mutual impediment and negative intumescence while maintaining effective sealing pressure.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The semi-rigid functional layer serves as an intermediary between the blowing agent and the external environment. It mediates the expansion forces, distributing them evenly and preventing the mutual impediment that occurs when blowing agents expand freely in all directions, thus preserving intumescence potential.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Reliability

If expansion causes densification of the material, then sealing is enhanced, but thermal conductivity increases leading to faster temperature rise

Engineering Contradiction:
Improvesealing capabilityVSAvoidthermal conductivity
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the density and porosity parameters through controlled expansion. The layered structure allows for optimal densification that achieves sealing without excessive compression, maintaining porosity levels that limit thermal conductivity and prevent rapid heat transfer to the protected side.

Inventive Principle:
Principle #35Parameter changes

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 enhances the sealing capability and ash crust stability of fire protection elements, reducing material usage while maintaining effective fire resistance and preventing fire spread, thus improving installation ease and environmental impact.

Implementation Method 1

These fire-resistant elements are generally made of or contain intumescent materials, so that the material expands when exposed to heat, such as that generated in a fire, thereby compressing the cable and sealing the opening in the building component.

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

the carrier material, including the intumescent additives, is applied to a film or fabric

Methodology Applied
Scientific EffectIntumescence: Intumescent Materials

Implementation Method 3

the functional layer (3) has a temperature resistance of at least 300 °C... the functional layer (3) comprises at least a semi-rigid material... distributes expansion pressure and maintains flexibility

Methodology Applied
Scientific EffectPressure distribution:

Data Source

PatentEP3870315B1Fire protection element for sealing holes in components
Publication Date: 2026.04.01 HILTI AG
  • EP3870315B1 patent drawingFigure 1~2
  • EP3870315B1 patent drawingFigure 3~4
  • EP3870315B1 patent drawingFigure 5

AI summary

The invention relates to a fire proofing element comprising a layered body for sealing passages in construction elements, such as building components, through which lines are guided. The invention further relates a process for manufacturing the disclosed fire proofing element as well as to the use of the fire proofing element for sealing passages and/or joints in construction elements against fires and fumes.