
377Fires
where
T is the temperature
T
a
is the ambient temperature
t is the time
k is the convective heat transfer coecient
We may then say
dT
kdt
−
=−
(12.48)
Integrating, we obtain
ln()
(12.49)
To evaluate the constant C, we ascribe T
0
as the temperature at time t = 0 so that
TT TT
kt
=+ −
−
ε
(12.50)
For air k = 1.0–1.4 Btu/(
2
-h°F).
Explosive Characteristics
Finely divided solid material (dusts and nes), when dispersed in air, can fuel particularly
violent and destructive explosions. Dust explosions occur in a variety of materials such
as grain dusts and sawdust, coal and charcoal, and a variety of chemicals. Since the com-
bustion ...