Standard Test Method for SURFACE BURNING CHARACTERISTICS OF BUILDING MATERIALS

Purpose: To measure and describe the properties of an insulating material in response to heat and flame in a fire test chamber.

General Information: In this test, surface burning characteristics to be identified are flame spread classification (FSC), fuel contribution and smoke developed. No standard correlation exists between these three characteristics, however.

The performance of the material during the test should not be considered a determination of the product's suitability for use after the test.

Standard values, by which performance is compared, are assigned a numerical 0 for asbestos-cement board and 100 for a select grade of red oak flooring for all three characteristics.

Apparatus: The 25'test tunnel apparatus consists of: a horizontal, rectangular duct with observation windows along one sidewall; a non-combustible removable top and an interior lining of firebrick. Several firebricks are positioned to act as baffles along the interior walls to facilitate proper ombustion. A gas burner (flame source) is positioned one foot from the "fire end" of the tunnel in front of the air intake. A fan at the opposite end of the tunnel ("vent end"), forces a draft through the apparatus at a specified velocity.

Equipment needed to measure smoke density consists of a light source and photoelectrical cell sensitive to the amount of light Received. Both are positioned at the vent end. Thermocouples measure temperature indicating the fuel contribution of the specimen (Fig. 13).

Method: The test chamber room must be properly ventilated so that the atmospheric pressure outside the apparatus is maintained during the test.

Test specimens of prescribed dimensions are conditioned to a constant weight.

The test apparatus is calibrated, adjusted and pretested using oak and asbestos cement board as test samples. Results are plotted for flame spread distance, temperature (fuel contribution) and photoelectric cell readings indicating smoke density.

Place the test specimen (building material) in a calibrated test tunnel and run the 10 minute test using the same procedure as with the oak and asbestos samples. Plot the results graphically in a manner similar to the pre-tests.