Page 5 - Caswell Firesafe Manual 2018

This Technical Manual relates to products specific to BS 476:Pt 24 (1987) testing which are widely
specified and used outside the European Economic Area. For products covered by EN 1366-1 & 8 test
standards, refer to our Technical Manual FIRESAFE / TM / 01 / EN / 2018

3 Testing Requirements

Standard ductwork systems (manufactured to DW144 or DW172 for kitchen extract systems) cannot be
used where fire resisting ductwork is specified.

The BS 476:Pt 24 (1987) tests are designed to simulate a fire in a compartment and the ability of a duct
penetrating the compartment wall / floor to resist the spread of fire from one compartment to another
without the use of fire dampers.

The tests include a fully assembled system attached to a fan and as such all aspects of the system are
subjected to the test conditions; including the joints, supports and the penetration seal within the
compartment wall / floor.

There are two test types as follows:

Duct A Fire Outside
Demonstrates the ability of the
duct to withstand a fire breaking
from outside the duct to inside
the duct and hence being able to
travel down the duct into another
compartment.

Duct B Fire Inside
Demonstrates the ability of the
duct to withstand a fire breaking
out of a duct and into another
compartment. These are
particularly relevant to kitchen
extract systems where the ignition
source is often at the canopy /
cooking appliances.

Typical test arrangement for horizontal ducts to BS 476:Pt24 (1987)

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