8
(Class A) smoke generate method
a) Combustible
– A wood brand formed of three layers of kiln dried fir strips, each strip 3/4 inch
(19.1mm) square in cross section, 6 inches (152 mm)long with six strips in each layer, is to be used.
Wood strips are to be nailed or stapled together with adjacent layers at right angles to each other.
Overall dimensions of the wood brand are to be 6 by 6 by 2-1/2 inches (152 by 152 by 64 mm). The
brand is to be supported on a 5-inch (127-mm) diameter ring support 3 feet (0.9 mm) above the test
room floor.
b) Promoter – The wood brand is to be ignited by burning 4 milliliters of denatured alcohol consisting
of 190 proof (95 percent) ethanol to which 5 percent methanol is added as a denaturant. The alcohol
is to be placed in a 1-1/2 inch (38 mm) diameter, 1-inch (25.4-mm) deep metal container, the bottom
of which is to be 3-1/2 inches (89 mm) below the bottom of the wood brand and centered so that the
flame does not break through the top of the wood brand. The container is to be supported by a 1/4-
inch (6.4-mm) hardware cloth. The alcohol is to be placed in the container no earlier than 30 seconds
prior to ignition.
c) Point of Ignition – Ignition is to be by probes in alcohol. Probe tips of the igniter are to be placed
as near the container lip as possible without arcing to the sides.
Ignition site Shelter / Time Curve
Smoke pattern of wood-oriented fire in different focal lenses
