Each type of construction product has its own way of expressing fire performance. Through this series, we explain how to read and interpret classification codes according to the relevant European standards.
Part 4 – Fire Resistance Classification of Multi Compartment Smoke Extraction Ducts
Multi-compartment smoke extraction ducts are designed to extract smoke from multiple fire compartments, which places specific demands on their fire resistance performance. Compared to ducts serving a single fire compartment, their behaviour under fire conditions must consider the interaction between compartments connected through the duct system.
Applicable standards
- Testing: EN 1366-8:2024
- Classification: EN 13501-4:2016
| Designation | Meaning | Note |
|---|---|---|
| E | Integrity | Duct C |
| EI | Integrity and Insulation | Duct A and Duct B |
| ttt | Classification period | 30, 60, 90, 120 min |
| multi | Smoke extraction from multiple fire compartments | |
| ve | Vertical orientation of duct | |
| ho | Horizontal orientation of duct | |
| S | Smoke leakage | |
| p | Negative pressure differential applied during the test | 500, 1000, 1500 Pa,
DIAP allows pressure application from (-p) Pa up to (+500) Pa |
How to read the classification
The classification distinguishes between integrity (E) and integrity with insulation (EI). These criteria define whether the duct prevents the passage of flames and hot gases (E), and additionally limits temperature increase on the unexposed side (EI), depending on the duct type.
The classification also includes the fire resistance time, expressed in minutes (e.g. 30, 60, 90, 120). This value defines the duration for which the duct meets the specified classification criteria under fire exposure.
An important element of the classification is also the orientation of the duct – vertical (ve) or horizontal (ho). The classification is only valid for the position in which the duct was tested.
Additional elements of the classification may include the smoke leakage criterion (S) and pressure conditions (p). These parameters provide further detail on the duct performance under defined test conditions, such as leakage limits and applied pressure levels.
The designation “multi” indicates that the duct is intended for smoke extraction from multiple fire compartments. This reflects the specific test setup and the resulting classification, where the duct system is assessed in conditions representing interconnected compartments.
Example
EI 120 (ho) S1500 multi
This classification describes a horizontal duct that maintains integrity and insulation for 120 minutes. The designation S1500 refers to the smoke leakage criterion verified under a pressure difference of 1500 Pa, and “multi” indicates its use for smoke extraction from multiple fire compartments.
