Based on past experience, it is known that the combination
of combustible and flammable materials and sources of ignition is
the main cause of machinery space fires. The combustible and flammable
materials involved in the majority of cases are oils, i.e., oil fuel,
lubricating oil, thermal oil, or hydraulic oil.
There are many potential ignition sources in a machinery
space, the most common being hot surfaces, e.g., exhaust pipes and
steam pipes. Overheating of machinery, ignition from electrical installations
due to short-circuiting or arcing of switchgear and other fault conditions
may result in fire. Other frequent ignition sources are those associated
with human activities, e.g., smoking, welding, and grinding.