CEA 4001 - Page 118

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B.3.2 Exposed plastic surface - unexpended
The Category should be increased to III or IV when the commodity has exposed plastic
surfaces comprising one or more sides or more than 25% of the surface area.
Examples:
metal parts in PVC storage bins;
shrink wrapped tinned foods.
B.3.3 Exposed plastic surface - expanded
Exposed expanded plastics are more severe than unexposed plastics. They should be treated as
Category IV.
B.3.4 Open structure
Materials having very open structures generally present a higher hazard than materials with a
closed structure. The high surface area together with high air access encourages rapid burning.
The increase in hazard can be very substantial particularly with ordinary combustibles.
Examples:
- cardboard;
- in empty boxes assembled it is Category II (due to ready air access);
- in rolls stored vertically it is either Category III or greater (Special Risk) depending on the
storage
method (closely stacked, banded or unbanded etc.).
B.3.5 Solid block materials
Materials in solid block form have a low surface area to volume/mass ratio. This reduces the burning
rate and permits a reduction in Category.
Examples:
- blocks of solid rubber, vinyl floor tiles in block storage etc..
NOTE: this configuration does not apply to blocks of expanded plastics (Category IV).
B.3.6 Granular or Powdered materials
NOTE 1: granular materials excluding expanded plastics that will spill out during a fire tend to
smother
the fire and are thus less hazardous than their basic material counterparts.
Examples:
- plastic granules used for injection moulding stored in cardboard boxes
NOTE 2: this configuration does not apply to rack storage.
B.3.7 No special configuration