INTRODUCTION
Because of the very nature of petroleum products, there are many hazards involved in the handling and
storing them. The greatest and most obvious is fire. However, we must not overlook the many health and
safety hazards in addition to fire that are also present in petroleum facility operations.
PART A - CLASSES OF FIRES
There are four main classes of fire. They are based on the combustion characteristics of the material that is
ignited:
Class A fire - These fires occur in combustible materials such as bedding, mattresses, books, cloth,
wood, and paper. The remains of these fires are charred embers.
Class B fire - These fires occur in flammable liquids such as gasoline, jet fuels, kerosene, oils, paints,
turpentine, grease, and tar.
Class C fire - These are electrical fires, and can occur in wiring, electrical switches, and generators.
Class D fire - These involve combustible chemicals and metals such as sodium, potassium, titanium,
magnesium, zirconium, and phosphorous.
PART B - NATURE OF FIRE
Three elements are required to start and sustain a fire:
Heat (source of ignition) such as sparks, open flame, or static electricity.
Oxygen (air) which is always present.
Fuel (vapors) which in petroleum operations include items such as MOGAS, diesel fuel, and JP4.
By removing or preventing the presence of any one of these elements, a fire can be prevented or
extinguished.
PART C - VAPORS
Vapor characteristics. In a fire, it is the vapor that actually burns.
Vapors are heavier than air and collect in low areas.
Vapors will hang low to the ground and spread over large areas.
On hot humid days vapors are produced in greater volume.
When vapors are allowed to collect, flash backs can occur as the vapors come in contact with a heat
source and the heat travels back to the source of the vapors, causing a fire and possibly an explosion.
A 1 to 8 percent ratio by volume of vapors when mixed with air will form an explosive range. An
explosive range is that point where the vapor and the air mixture will burn. A mixture above 8 percent is
too rich in vapors and will not ignite. A mixture below 1 percent is too lean in vapors (too rich in air) and
will not ignite.
Control of vapors.
Empty containers (5 gallon, 55 gallon) that have previously contained petroleum product are more
dangerous than full ones. Fill the containers as soon as possible, or when stored empty, ensure caps
and bungs are on tight.
Store containers that have fuel in them or containers that previously contained product in a safe area.
Do not overfill, or fill containers at too fast a rate as vapors will be displaced to the atmosphere and
become a hazard.
Repair leaking pipes and containers as soon as possible.
Clean up spills immediately (as long as the contamination is present, vapors are a hazard).
Sources of ignition. A source of ignition can be a flame, spark, or other heat generating mode. Some
of the most common causes of heat are:
Smoking material (i.e., matches, lighters, and cigarettes).
Sparks (i.e., static electricity, moving fuel, moving equipment, welding and cutting).
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QM 5092
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