gases when burned. Because of these properties, packing and stowage
requirements are important. Although some general comments are made
in the introduction to the class, more detailed information is given
in the individual schedules.
Common products which appear in this class are charcoal; celluloid
scrap, copra, wet or oily cotton, iron oxide, some plastics,
fishmeal, and seed cakes.
Class 4.3 - Substances which, in contact with water, emit inflammable
gases
Because the products in this class give off gases which are sometimes
subject to spontaneous ignition and are also toxic, fire fighting is
a particular problem.
The use of water, steam, or water-foam extinguishers may make matters
worse. Even the use of carbon dioxide can do more harm than good in
some situations.
Common products in this class include calcium carbide, powder
derivatives
of
aluminum
and
calcium,
ferrosilicon,
lithium,
magnesium-based products, potassium-based products, rubidium, sodium,
and zinc.
Class 5 - Oxidizing Substances (Agents) and Organic Peroxides
This class is divided into two subclasses.
Class 5.1 deals with
oxidizing substances which, although not necessarily combustible
themselves, may increase the risk and intensity of a fire by giving
off oxygen.
Class 5.2 includes organic peroxides most of which are
combustible.
Class 5.1 - Oxidizing substances (agents)
The fact that all substances in this class give off oxygen when
burned creates obvious fire-fighting difficulties.
Some substances
may also be sensitive to impact, friction, or a rise in temperature.
Still others may react vigorously with moisture, thereby increasing
the risk of fire.
Mixtures of these agents with organic and combustible materials are
easily ignited. As such, they may burn with explosive force. Also,
you can expect a violent reaction between most oxidizing substances
and strong liquid acids, which in turn emit highly toxic gases.
One fire-fighting problem is caused by the fact that, since
substances in this class give off oxygen when burned, the use of
steam, carbon dioxide, or other inert gas extinguishers may be
ineffective.
18
TR1029
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