Page 144 - Dust Explosions in the Process Industries

Dust Explosions: An Overview 1 17

Figure 1 .I 34 Hazardous construction of factory
buildings. Minor overpressures due to an internal
dust explosion displace and break the weak walls
and cause the roof and floors to fall.

In the past, floors and roofs of factory buildings were often supported by recesses in
comparatively weak walls with no reinforcement, as illustrated in Figure 1.134(a). In the
case of an explosion, the walls were displaced outward, even at very modest overpres-
sures, and the floors and roof fell down into the building, as illustrated in Figure 1.134(b).
Clearly, under such circumstances the consequences of even minor dust explosions in
the building could be catastrophic.
However, if the building is constructed of reinforced concrete, it can be made suffi-
ciently strong to enable the windows to serve as vents. Figure 1.135 shows an actual exam-
ple of successful venting of an explosion inside a building through the windows. It is
important, however, to ensure that flying pieces of glass present no hazard to humans.
To avoid this hazard, it may be necessary to replace glass panes with anchored, trans-
parent plastic panes.

Figure 1 .I 35 Result of malted barley dust explo-
sion in grain silo facility in Oslo, Norway, in 1987.
The windows provided sufficient venting to pre-
vent destruction of building, which is of reinforced
concrete (Courtesy of A. F. Johansen, Oslo Port
Silo, Norway).