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 9999:2017 Clause 33.5.4)
- Such areas would typically include: boiler rooms, solvent extracts, specialist dust extracts and lift ventilation ducts.
The extract ductwork system ( shown ) must be suitable for clearing fumes and smoke. The system should normally be rated for a minimum of one hour integrity and maintain at least 90% cross sectional area.
Where the ductwork leaves the compartment from which it serves ( shown ) it must maintain integrity and insulation fire ratings for the same period of time as the compartment through which it passes.
All fire rated ductwork and penetration seals must be tested to BS EN 1366-8 and classified in accordance with BS EN 13501-4 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