Ventilation & Smoke Extraction

Fire protection requirements for ventilation ducts are directly related to their design function, the nature and behaviour of the fire and the construction materials that fuel the fire load. The fire resistance performance of the ventilation duct itself also plays a critical role. It is possible to prevent fire spread from one fire compartment (e.g. between floors) to another, along stairways and general access corridors only if all building materials and structural elements share a common fire classification and fire resistance rating. Typical steel sheet ducts fail to meet internationally accepted fire protection requirements. They heat and deform rapidly from the effects of fire. In certain circumstances they even accelerate the spread of flame and smoke.

Fire Rated Ductwork

Promat offers a wide range of solutions for self-supporting systems as well as particularly onerous conditions e.g. where high impact strength is required or for use in aggressive environments.

Use for

Service enclosures
Protected shafts
Smoke / ventilation ducts
Gas pipes
Kitchen extract ducts
Cable protection

More information available in the Fire Protection Handbook and Technical Data Sheets.

Ducts: Design Considerations

The relative complexity of any ductwork system which is passing through different fire compartments and the relevance of the system’s function in ambient and fire conditions can make the selection of a suitable ductwork system difficult.

To determine the fire resistance of ducts (without the aid of fire dampers) passing through or between compartments, the system should normally be tested or assessed in accordance with BS 476: Part 24: 1987 or equivalent local legislation.

Factors for consideration when determining the correct specification to ensure ducts will provide the required fire performance include:

Required fire exposure
Required fire performance
Supporting structure
Hanger support
Steel ductwork
Penetrations through walls and floors
Ductwork functions
Acoustic performance
Thermal insulation
Water tolerance
Strength and appearance
Access requirements (hatches) for inspection

Chapter 6 of the Fire Protection Handbook includes a ductwork system selector, examples of system specifications for a range of fire rated ductwork applications and required fire protection periods. Additional system details are available in the Technical Data Sheets.

Cable Protection: Design Considerations

In the event of a fire it may be vital to the safety of the building occupants that certain electrical systems and services remain functioning until all personnel have escaped. Such systems will therefore require protection from fire for a specified period of time.

The following points are some of the factors which should be considered when determining the correct specification to ensure the cable duct system will provide the required fire performance.

Required fire exposure
Required fire performance
Supporting structure
Penetrations through walls and floors
Acoustic performance
Thermal insulation
Water tolerance
Strength and appearance
Failure temperature of the cable
Maximum cable operating temperature

Chapter 6 of the Fire Protection Handbook includes required board thickness tables, examples of system specifications for a range of fire rated ductwork applications and required fire protection periods. Additional system details are available in the Technical Data Sheets.

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Technical Documentation

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