High risk areas
Ductwork systems extracting fine powders or chemical solvents are considered to have an increased fire risk.
- Areas of high risk will require separate and independent extract systems (BS 9999:2008 Clause 33.4.2.)
- Such areas would typically include: boiler rooms, solvent extracts, specialist dust extracts and lift ventilation ducts.
In the diagram
The duct systems (shown) must all be suitable for resisting fire from inside (Type B) and rated for stability and integrity. Insulation rating is not required in the first compartment.
In all the remaining areas the duct (shown ) must retain stability and insulation fire rating for the same period of time as the compartment through which it passes - this may be required for the remainder of the route of the ductwork, through the building to the outside.
In some circumstances insulation requirements may be waived by the regulatory authority if there are no combustible materials within 500mm of the duct, such as in plant room (shown ) – BS 9999:2008 Clause W.4.
All fire rated ductwork and penetration seals must be tested to BS 476-24/ISO 6944 or BS EN 1366-1 and classified in accordance with BS EN 13501-3 by a recognised NAMAS/UKAS accredited laboratory.
Note: Final approval must always be obtained by the local building control officer/fire department prior to commencement of construction