BS 476 Part 22

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Summary of BS 476: Part 22: 1987 Method for determination of the fire resistance of non-loadbearing elements of
construction

PurposeThis part of BS 476 describes procedures for determining the fire resistance of non-loadbearing elements of building construction when subjected to the heating and pressure conditions specified in BS 476: Part 20. This part is applicable to vertical partitions, to fully, partially insulated and uninsulated vertical doorsets and shutter assemblies (except fire dampers incorporated in ducts, to ceiling membranes, and to glazed elements).


MethodThe test conditions and apparatus are specified in BS 476: Part 20.

1.
Determination of fire resistance of partitions and non-loadbearing walls providing vertical separation
a.
Test specimen:
Noemally two specimens (at least 3m by 3m) are tested. The specimen incorporates any mechanical joints in the element and any services where these form an integral part of the element as used in practice.
b.
The procedure:
The test is carried out in accordance with BS 476: Part 20. The unexposed face of the specimen is monitored for integrity and insulation in accordance with Part 20, and failure is determined with respect to these two parameters.

2.
Determination of fire resistance of doorsets, shutter assemblies, lift landing doors and other essentially vertical separating elements designed to allow the ingress of personnel or goods
a.
Test specimen:
Normally two specimens are tested, the specimen being full size and mounted within an appropriate section of associated construction.
b.
The procedure:
The test is carried out in accordance with BS 476: Part 20. Fully and partially insulated structures are monitored for integrity and insulation and uninsulated structures for integrity only and their fire resistance determined with respect to those criteria. The result is stated in terms of the elapsed time between commencement of heating and time of failure.

3.
Determination of fire resistance of ceiling membranes
a.
Test specimen:
A single specimen of at least 4m by 3m is tested from its underside. The specimen should include joints, diffuser grilles, lighting fittings and associated wiring which form integral part of the element in practice.
b.
The procedure:
The test is carried out in accordance with BS 476: Part 20 and observations made of the behavior of the specimen including the mode of failure in the event of collapse. The fire resistance of a ceiling membrane is determined with respect to integrity and insulation, and the results stated in terms of elapsed time between the commencement of heating and the time of failure.




4.
Determination of fire resistance of glazed elements (where over 50% of the surface is glazing)
a.
Test specimen:
Normally two specimens of at least 3m by 3m are tested, the specimen being constructed and finished as used in practice. The specimen is mounted in an associated construction of a wall, partition or door of the type to be used in practice or, if not known, in a construction that has a recognized fire resistance greater than that anticipated for the specimen being evaluated. The method of fixing the specimen to the associated construction is representative of that used in practice.
b.
The procedure:
The test is carried out in accordance with BS 476: Part 20 and the fire resistance shall be determined with respect to integrity and insulation. The result is stated in terms of elapsed time between the commencement of heating and the time of failure.


The standardized temperature / time conditions used in this evaluation are representative of only one possible fire exposure condition at the fully developed fire stage and the method does not quantify the behaviour of an element, for a precise period of time, in a real fire situation. In addition, due to restrictions of size and the absence of surrounding construction, the laboratory test cannot reproduce the actual behaviour pattern of an element in a fire. However, test data can provide a basis for making engineering evaluations.