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 3 – Fire Resistance Classification of Single Compartment Smoke Extraction Ducts
This type of duct has a specific position within the European standardization system – both testing and classification are focused exclusively on its performance during smoke extraction within a single fire compartment. For this product, no EXAP (Extended Application) standard exists; therefore, the field of application is always limited to the test conditions, permitted modifications under direct application of test results, and the classification designation stated in the classification report.
Applicable standards
- Testing: EN 1366-9:2024
- Classification: EN 13501-4:2016
- Extended application of test results: No EXAP standard exists
| Designation | Meaning | Note |
|---|---|---|
| E₃₀₀ | Integrity tested at maximal temperature 300 °C | Test method EN 1366-9 does not allow testing at 300 °C |
| E₆₀₀ | Integrity tested at maximal temperature 600 °C | |
| ttt | Classification period | 30, 60, 90, 120 min |
| S | Smoke leakage | |
| p | Negative pressure differential used during the test | 500, 1000, 1500 Pa, DIAP allows pressure application from (−p) Pa up to (+500) Pa |
| ho | Horizontal orientation of the duct | Test method EN 1366-9 allows testing of horizontal duct orientation only |
| single | Suitable for single fire compartment application | |
How to read the classification
The basis of the classification is the integrity criterion (E) assessed at elevated smoke temperatures. The test is not carried out using the temperature–time curve defined in EN 1363-1, but at a defined maximum temperature, expressed in the classification as E₃₀₀ or E₆₀₀.
The classification also includes the time designation “t” (30, 60, 90 or 120 minutes), which is always inseparably linked to the corresponding temperature level.
The classification applies exclusively to horizontal orientation (ho), as the test method EN 1366-9 does not foresee vertical installation of this type of duct. Direct application of the test standard allows the results of the horizontal test to be applied also to vertical parts of the duct run within a single compartment.
A mandatory part of the classification is the smoke leakage criterion (S), stated together with the pressure level p (500, 1000 or 1500 Pa) at which smoke tightness was verified during testing under negative pressure conditions.
An integral part of the classification designation is the term “single”, which clearly limits the use of the duct to one fire compartment only. This classification does not apply to penetrations between fire compartments and cannot be interpreted as general fire resistance of the duct.
Example
E₆₀₀ 120 (ho) S1500 single
This designation represents a duct maintaining integrity at 600 °C for 120 minutes, in horizontal orientation, with smoke tightness verified at –1500 Pa, intended for use within a single fire compartment only.
