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Fire Rated Ductwork

  • Promat Applications - Fire Rated Ductwork

ADVANTAGES

  • 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.

Fire Rated Ductwork

Promat offers a wide range of solutions for proprietary “off the shelf” fire rated ductwork, the protection of steel ductwork and for self-supporting systems as well as particularly onerous conditions e.g. where high impact strength is required or for use in aggressive environments.

  • 30-240 minutes fire resistance 

More Information

i  FP Handbook: Chapter 6

i  Testing and Certification

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. 

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.

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.



Ducts: 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. This standard has been written specifically for ventilation ducts, but guidance is also given in the standard on the performance requirements for ‘smoke outlet’ ducts and ‘kitchen extract’ ducts.
For any size of duct, the tensile stress in the steel hangers must not exceed the maximum permitted stress for each fire resistance period based on BS 5950: Part 8: 2003. If these stress levels are exceeded then the size of the hanger rods must be increased, or the centres of the hangers reduced or the hangers protected. The penetration of the hanger fixings into any concrete soffit should be a minimum of 50mm for 120 minutes ratings or 65mm for 240 minutes ratings.

Service enclosures: for the provision of fire resisting constructions to general building services, 60 to 240 minutes fire rating (integrity with varying periods of insulation), in accordance with the performance criteria of BS 476: Part 20: 1987.
Chapter 6 of the Fire Protection Handbook  includes further information.

Fire Protection Handbook

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Technical Data Sheets

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