Extension Frame Chamber Layout for Fire-Safe Cable Penetrations

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Solution Overview

Problem

Existing cable and pipe transition systems face challenges in maintaining fire integrity and insulation without derating the capacity of power cables, especially when additional insulation is not allowed due to pollution concerns.

Innovation Solution

The use of extension frames with strategically placed intumescent material strips and chambers to manage heat transfer, ensuring fire protection without additional insulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If additional insulation is added on the cables to achieve fire protection, then fire integrity and insulation criteria are improved, but cable capacity is derated

Engineering Contradiction:
Improvefire integrityVSAvoidcable capacity
Core Design Contradiction:
ReliabilityVSPower

Solution Approach 1:

The transition system is divided into multiple chambers (first chamber, second chamber, third chamber) separated by fire protection elements. Each chamber serves a specific function: the first chamber receives cables, the second chamber contains intumescent material for fire protection, and the third chamber provides additional sealing. This segmentation allows fire protection without adding insulation directly to cables, thus maintaining cable capacity while achieving fire integrity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Intumescent material is introduced as an intermediary substance between the cables and the external environment. This material remains stable at normal temperatures but expands when exposed to fire, providing thermal insulation dynamically. The intermediary approach protects cables from heat transfer without requiring permanent insulation that would derate cable capacity.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Temperature

If additional insulation is added on the cables to achieve fire protection, then temperature insulation is improved, but the system complexity increases

Engineering Contradiction:
Improvetemperature insulationVSAvoidsystem complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The system uses parameter changes of the intumescent material based on temperature conditions. At normal operating temperatures, the material remains compact and does not interfere with cable installation or increase system complexity. When exposed to fire temperatures, the material undergoes volumetric expansion, automatically providing thermal insulation. This parameter-based response achieves temperature insulation without requiring complex active control systems or permanent structural modifications.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If intumescent material is used for fire protection, then fire insulation is improved, but heat transfer to the non-fire side increases without proper chamber design

Engineering Contradiction:
Improvefire insulationVSAvoidheat transfer
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The transition is divided into multiple chambers with the intumescent material placed in a dedicated second chamber between the first chamber (cable entry) and third chamber (sealing chamber). This segmentation creates thermal zones that progressively resist heat transfer. The chamber structure ensures that expanding intumescent material effectively blocks heat pathways to the non-fire side while maintaining organizational simplicity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The fire protection system uses a nested chamber structure where the first chamber (cable receiving), second chamber (intumescent material), and third chamber (sealing) are nested sequentially. This nesting arrangement allows the intumescent material to be positioned optimally within the transition structure, maximizing its fire insulation effectiveness while containing heat transfer within defined spatial boundaries.

Inventive Principle:
Principle #7Nested doll (Nesting)

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 system effectively maintains fire protection and insulation performance while preventing heat transfer to the non-fire side, without derating cable capacity.

Implementation Method 1

Intumescent material is a material that swells when exposed to excessive heat, such as in case of fire

Methodology Applied
Scientific EffectIntumescent material swelling: Intumescent Materials

Implementation Method 2

By means of the compression unit the modules are compressed in one direction in such a way that the modules will seal inwards around the cables and/or pipes

Methodology Applied
Scientific EffectCompression sealing: Compression

Data Source

PatentEP3682514B1Extension frame
Publication Date: 2025.12.10 ROXTEC AB
  • EP3682514B1 patent drawingFigure 1~3
  • EP3682514B1 patent drawingFigure 4~6
  • EP3682514B1 patent drawingFigure 7~8

AI summary

The present invention concerns an extension frame (1, 7, 18, 27) comprising a flange (2, 8, 19, 29, 31) and a box (3, 9, 20). The flange (2, 8, 19, 29, 31) is placed at one end of the box (3, 9, 20). A through opening is formed going through the centre of the box (3, 9, 20) and through the flange (2, 8, 19, 29, 31). A number of holes (4, 5, 10, 11, 21, 22, 33, 34) are provided going through walls of the box (3, 9, 20). Further, a system comprising two extension frames (1, 7, 18, 27) are formed. The two extension frames (1, 7, 18, 27) are placed on opposite sides of a through opening of a partition. A sealing devices (25) for cables or pipes is placed in said through opening of the partition.