CPD PROGRAMME | FIRE PROTECTION for the penetrated wall or floor must be maintained so that fire does not spread between compartments. Fire-rated kitchen extraction. This is a particular hazard, as combustible deposits such as grease are likely to accumulate on ductwork system internal surfaces, and may spread fire if ignited. Fire-rated smoke extraction that extracts smoke from a building in the event of fire needs to be fire resistant, but also able to continue to perform the primary function while under fire conditions. Each of these applications of ductwork systems should be tested against appropriate standards. Prior to design and deployment, the application for each section of ductwork should be identified and the appropriate fire rating established (in terms of ductwork integrity, stability, and insulation rating see Defining fire performance panel). In practice, it is particularly important for this to be carefully considered at the earliest stages of the project so that the ductwork is designated and tested appropriately. Legislative requirements for larger sizes of ductwork (in most cases to an upper size limit, as will be discussed later), for both ventilation and fire, are well documented. It is not uncommon3 that consultants specify, by agreement, that the most appropriate A section of ventilation standard that should be adopted is BS 476-24. However, this is not a path to obtaining a declaration of conformity. Although ducts were previously under the auspices of BS 476-24 testing methods, this has been superseded by BS EN 12101-7 for smoke extraction. However, it is not uncommon3 for BS 476-24 to continue to be applied and accepted for all ducts. Care needs to be taken over what is being supplied with reference to BS 476-24, as smoke-control ducts must conform to BS EN 12101-7, which specifies requirements and identifies test methods for smoke-control duct sections and their associated components. For test requirements, this standard refers to BS EN 1366-1, with the tests conforming to BS EN 1366-8 and BS EN 1366-9. The methods for the associated classification of results are taken from BS EN 13501-4. As BS EN 12101-7 provides a harmonised standard for smoke-extraction ductwork applications, the resulting tested product can be CE marked. Fire-resisting ventilation ductwork and kitchen extract ductwork should conform to the (draft) product standard EN 15871, which specifies test methods, verification and marking procedures. However, as this is still in draft, no CE marking is yet possible, and it has yet to supersede BS476-24 for these two applications. The Association for Specialist Fire Protection (ASFP) recommends4 that kitchen extract duct should be tested under BS EN 1366-1 (test for combustible linings) as this would be considered a more technically robust method than defaulting back to BS 476-24. There are several practical limitations on the size and design of elements that can be tested by the standard methods. Direct test results are only allowed up to 1,250mm x 1,000mm or 1,000mm diameter, so CE marking can only currently be applied up to this size. When these ducts are larger, or are of a modified design, it is necessary KEY STANDARDS BS 476-24:1987, ISO 6944:1985 Fire tests on building materials and structures. Method for BS EN 1366-1:2016 (2019 revision in draft) BS EN 1366-8:2004 extraction ducts (2019 revision in draft) BS EN 1366-9:2008 extraction ducts BS EN 12101-7:2011 BS EN 13501-3:2005 (2019 EN revision in draft) BS EN 13501-4:2016 BS EN 15882-1 4 66 April 2021 www.cibsejournal.com CIBSE April 21 pp65-68 CPD 177.indd 66 26/03/2021 14:47