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BS:EN 1366-1:2014 - Fire Resistant tests for Service Installations Ducts (Ventilation, Pressurization & Kitchen Extract Duct)

This is primarily the fire test for Ventilation ducts and Kitchen Extracts, but it is also used as a precursor to the Smoke Extract ducts where fire insulation is required to be demonstrated.

The performance of the duct assembly is measured in terms of its ability to withstand exposure to high temperatures by setting criteria by which the resistance of the fire containment (integrity), the thermal transmittance (insulation) functions, together with the leakage rate of the duct can be judged. The standard temperature/time fire exposure is specified in BS EN 1363-1.

A. Performance criteria

  1. Insulation

    Insulation failure shall be as defined in BS EN 1363-1. Only thermocouples placed a distance of 325mm from the duct penetration detail, outside the furnace shall be used to determine the average temperature rise (140°C of test specimen). All fixed thermocouples and roving thermocouples may be used to determine maximum temperature (180°C) rise.

    Ducts with combustible linings (Kitchen Extract) are subject to the insulation failure criteria in BS EN 1363-1. Also additional thermocouples are placed inside the duct & inside the furnace (Duct A fire outside).

  2. Integrity

    Integrity failure is determined in BS EN 1363-1 where a cotton pad is ignited or when sustained flaming of duration of at least 10 seconds appears on the unexposed face of the test specimen outside the furnace.

B. Direct field of application for Ducts up to 1250mm x 1000mm rectangular & 1000mm circular

The direct field of application only covers circular and 4 sided rectangular Ducting currently.
Test results achieved for horizontal Ducts A (fire outside) and B (fire inside) are applicable to horizontal Ducts only.
Test results achieved for vertical Ducts A and B is applicable to vertical Ducts only.

The test result obtained for the standard size of Ducts A & B is applicable to all dimensions up to the size tested together with the increase as follows:

Fire Outside (Duct A) plus 250mm wide, plus 500mm high (for rectangular Ducts) plus 200mm diameter (for circular Ducts). Hence tested Duct size is 1000mm x 500mm therefore suitable for Duct sizes up to 1250 x 1000mm.

Fire Inside (Duct B) plus 250mm wide, plus 750mm high (for rectangular Ducts) plus 370mm diameter (for circular Ducts). Hence tested Duct size is 1000mm x 250mm therefore suitable up for Duct sizes up to 1250mm x 1000mm.

This means under the field of direct application, the largest Ducts, for Duct A and B will be 1250mm wide x 1000mm high (for rectangular Ducting) and 1000mm diameter (for Circular Ducting). Assessments for larger sizes are not acceptable.

C. Suspension Devices (Drop Rods Etc.)

Unprotected suspension devices must not be longer than 1500mm without insulation protection to ensure a max permissible extension of 40mm is not exceeded.

For unprotected suspension devices of approximately 1500mm length an elongation of 40mm can be expected for 2 hour fire resistant period.

As the test configuration does not allow an assessment of the load bearing capacity, the suspension devices shall be made of steel and be sized such that the calculated stresses do not exceed the values.

Tensile stress for vertically orientated

Components on horizontal Ducts.

Up to 60 min

9 N/mm2

60 min < 120 min

6 N/mm2

Suspension devices (drop rods) between 1500mm and 4000mm long shall be insulated to ensure that the drop rods do not expand by a maximum of more than 40mm. The drop rod should be tested inside the furnace and subject to the maximum weight that the drop rod would have to bear in practice.

D. Extended field of application for EN1366-1 Ducting

BS EN 15882-1 Extended application of results from fire resistance tests for Service installations Part 1: Ducts (Non Smoke)

When a fire rated Duct is required larger than that covered under the direct field of application, the system must be tested to BS EN 15882-1. This allows for the Duct to be tested up to a maximum size of 2500mm x 1250mm for rectangular ducts and 1250mm diameter for circular Ducts both A & B. Larger sizes of fire rated duct will not be permitted except by an individual project specific submission Etag.