476-4 is a non-combustibility test for building materials, generally applicable to non-combustible or inorganic materials, and not suitable for organic or plastic materials. Refer to the product scope specified in the standard:

476-4 Non-combustibility Test - Product Scope:

This British standard specifies the test method for determining whether a building material is non-combustible.

Based on the performance structure of the non-combustibility test, materials used in building structures and surfaces are classified as "non-combustible" and "combustible".

This test is intended for building materials, regardless of whether the surface has a coating, but it is not intended for a single coating alone.

How to prepare samples for the 476-4 test for building materials? Refer to the following sample dimensions:

Three samples must be prepared, with the dimensions of each sample as follows:

Length and width: m

Height: 50±3mm,

Volume: 800±50cm³

Tips on cylindrical thickness and diameter:

If the thickness of the material is less than the specified height, each sample must be built up to this thickness by stacking sufficient layers. These layers must be placed flat in the sample holder and tightly bound with fine wire to avoid gaps between layers, but must not be compressed. The density of the sample must represent the actual density of the material.

For composite materials, if stacking an integer number of layers cannot achieve the required sample size, adjust the thickness of different components so that the proportion of each component in the sample is the same as that of the material being tested. If neither of these methods is feasible, test each independent component layer separately and issue separate reports.

Before testing, samples need to be conditioned:

Before testing, samples must be baked in a ventilated oven at 60±5°C for 24 hours, then cooled to room temperature in a desiccator containing anhydrous calcium chloride.