Smoke Visibility Parameters

These parameters define the substance being burned, the type of fire (smoldering or flaming), and the sign illumination type for Smoke Visibility simulations:

Extinction coefficient

The extinction coefficient characterizes the mode of combustion:

Type of Combustion	Specific Extinction Coefficient (ft²/lbm)
Smoldering combustion	21000
Flaming combustion	37000

Note: Specify the value of extinction coefficient in units of ft2/lbm.

Sign visibility constant

The sign visibility constant characterizes the visibility of the sign:

Type of Situation	Constant
Illuminated sign	8
Reflecting sign	3
Building components in reflected light	3

Combustion particulate yield for several combustible materials

The combustion particulate yield is the particulate content of the smoke based on the burning fuel. It is an important parameter for characterizing the translucency of the smoke.

Combustible Material	Particulate Yield
Wood (red oak)	0.015
Wood (Douglas fir)	0.018
Wood (hemlock)	0.015
Fiberboard	0.008
Wool (100%)	0.008
Acrylonitrile-Butadiene-Styrene (ABS)	0.105
Polymethylemathacrylate (PMMA; Plexiglas^TM)	0.022
Polypropylene	0.059
Polystyrene	0.164
Silicone	0.065
Polyester	0.09
Nylon	0.075
Silicone Rubber	0.078
Polyurethane Foam (Flexible)	0.188
Polyurethane Foam (Rigid)	0.118
Polystyrene Foam	0.194
Polyethylene Foam	0.076
Phenolic Foam	0.002
Polyethylene (PE)	0.06
Polyvinylchloride (PVC)	0.172
Ethylenetetrafluoroethylene (ETFE; Tefze^TM)	0.042
Perfluoroalkoxy (PFA; Teflon^TM)	0.002
Fluorinated Polyethylene-Polypropylene (FEP; Teflon^TM)	0.003
Tetrafluoroethylene (TFE; Teflon^TM)	0.003