[F] 909.10.1 Exhaust Fans
Components of exhaust fans shall be rated and certified by the manufacturer for the probable temperature rise to which the components will be exposed. This temperature rise shall be computed by:
c = Specific heat of smoke at smoke layer temperature, Btu/lb°F (kJ/kg • K).
m = Exhaust rate, pounds per second (kg/s).
Qc = Convective heat output of fire, Btu/s (kW).
Ta = Ambient temperature, °F (K).
Ts = Smoke temperature, °F (K).
Exception: Reduced Ts as calculated based on the assurance of adequate dilution air.