BS 476 Part 7 specifies a method of test for measuring the lateral spread of flame along the surface of the specimen of a product orientated in the vertical position under opposed flow conditions, and a classification system based on the rate and extent of the spread of flame. It provides data suitable for comparing the end-use performances of essentially flat materials, composites or assemblies, which are used primarily as the exposed surfaces of walls and ceilings.
This Surface Flame Spread Apparatus consists of a radiation panel mounted vertically in a surround and supported on a framework.
The radiation panel is sullied with an gas-air mixture.
The radiation panel is 850mm square for a porous refractory type burner block designed to give efficient combustion of the air-gas-air mixture, with no flaming occurring on the face of the panel under operational conditions.
The radiation panel and its surround are supported on a framework so that the center of the panel is about 1250±100mm above floor level.
A specimen holder and a pilot flame arrangement mounted to one side of the apparatus.
The specimen holder is comprise a water-cooled steel frame with water-cooled face plates. The face plates is overlap the specimens by 20±2mm on their top and bottom edges and over the vertical edge adjacent to the radiation panel.
A spring loaded clamp is positioned to clamp the specimen against the face plates.
The portable water supply to the specimen holder make the maximum temperature does not exceed 35℃ at the outlet from the specimen holder.
The specimen holder assembly is located at 90±2° to the face of the radiation panel and in such as way that the faces of the top and bottom guides of the specimen holder are in the same plane as the inside face of the surround to the radiation panel.
The height of the specimen holder is hinged to allow it to be swung horizontally, away from the face of the radiation panel between tests, from the test position to the standby position and vice-versa.
The pilot burner is consist of a steel tube.
The gas and air supply lines to the radiation panel contain flow meters, pressure regulators, control valves and safety devices.