Page 12 - Caswell Firesafe Manual 2018

TECHNICAL MANUAL

FFRDL / TM / BS / 01 / 2018

Kitchen Extract Systems

Kitchen Extract systems are designated as standalone systems due to the odours and oil particulates
contained in the air that is extracted from cooking appliances.

As stated previously, fire dampers must not be used in Kitchen Extract systems. If it is not possible to discharge
directly to atmosphere from the kitchen compartment then the ductwork that penetrates the compartment
wall or floor must be fire resisting to the point of discharge.

The diagram opposite illustrates a typical Commercial Kitchen Extract system.

BRITISH STANDARD VERSION
TYPICAL NON-DOMESTIC KITCHEN EXTRACT SYSTEM
SUITABLY FIRE PROTECTED FAN
ROOF PLANT ROOM
PENETRATION SEALS
TO BS 476 PT24

ALTHOUGH THIS SECTION OF DUCTWORK NEED
ONLY HAVE A 30 MINUTE PERIOD OF FIRE
RESISTANCE FOR THE PURPOSE OF MEANS OF
ESCAPE; IT IS GOOD PRACTICE TO EXTEND THE
HIGHER STANDARD OF FIRE RESISTANCE USED
FOR COMPARTMENTATION TO THIS SECTION FOR
SIMPLICITY.
ROOM 1
FIRE FIRE RESISTING
RESISTING DUCT NOT
DUCT NOT REQUIRED
REQUIRED
KITCHEN KITCHEN
GENERAL SERVICES
SHAFT WHICH COULD
CONTAIN OTHER SERVICES EXTERNAL
WALL
SUITABLY FIRE PROTECTED FAN
FIRE COMPARTMENT FLOOR
FAN
RESTAURANT KITCHEN
FAN
ROOM
NOTE: THERE SHOULD BE NO FIRE DAMPERS WITHIN
NON DOMESTIC KITCHEN EXTRACT SYSTEMS
FIRE RESISTING WALLS (for compartmentation) FIRE RESISTING KITCHEN EXTRACT DUCT, STABILITY,
FIRE RESISTING FLOORS (for compartmentation) INTEGRITY AND INSULATION RATING EQUAL TO
FIRE RESISTING WALLS (for means of escape purposes only) COMPARTMENT WALL
NON-FIRE RESISTING WALLS 30 MINUTE FIRE RESISTING KITCHEN EXTRACT DUCT,
STABILITY, INTEGRITY AND INSULATION RATING FOR
MEANS OF ESCAPE PURPOSES
Note: Some walls need to be fire resisting for means of escape and compartmentation
reasons such as the stairway and special fire risk areas such as the boiler house. ELEVATION
In such cases the higher fire time is illustrated in colour.
Fully welded systems
DW172 recommends the use of fully welded Kitchen Extract systems as their construction is specifically
designed to prevent grease and cooking fats leaking from the ductwork.

Certain types of cooking appliances may not generate excessive amounts of grease laden air and it is the
responsibility of the designer to specify whether or not a fully welded system is required. They should state or
seek advice on the material to be used in the ductwork construction i.e. galvanised mild steel, fully welded mild
steel or fully welded stainless steel.

Irrespective of the material used to manufacture the ductwork, the system must be fire resisting if it breaches
the kitchen compartment.

12 www.firesafeductwork.co.uk