Class A Fire
Prevent ordinary combustibles from becoming a fire by:
- Keeping storage and working areas free of trash
- Placing oily rags in covered containers
Class B Fire
Prevent flammable liquids or gases from becoming a fire by:
- Keeping flammable liquids stored in tightly closed, self-closing, spill-proof containers
- Pouring from storage drums only what you’ll need
- Not refueling gasoline-powered equipment in a confined space, especially in the presence of an open flame such as a furnace or water heater
- Not refueling gasoline-powered equipment while it’s hot
- Storing flammable liquids away from spark-producing sources
- Using flammable liquids only in well-ventilated areas
Class C Fire
Prevent electrical equipment from catching fire by:
- Protecting utility lights with some type of wire guard (Heat from an uncovered light bulb can easily ignite ordinary
- Looking for old wiring, worn insulation, and broken electrical fitting
- Reporting any hazardous condition to your supervisor
- Preventing motors from overheating by keeping them clean and in good working order (A spark from a rough-running motor can ignite
the oil and dust in it)
- Not misusing fuses (Never install a fuse rated higher than specified for the circuit)
- Investigating any appliance or electrical equipment that smells strange (Unusual odors can be the first sign of fire)
- Not overloading wall outlets (Two outlets should have no more than two plugs)
Class D Fire
Prevent a fire from flammable metals by adhering to the following recommendations:
Store white phosphorus in a sealed container with a non-reactive solution to prevent contact with air (It is air-reactive and will burn or explode on contact with room air).
Magnesium & Titanium
Flammable metals such as magnesium and titanium generally take a very hot heat source to ignite; however, once ignited are difficult to extinguish as the burning reaction produces sufficient oxygen to support combustion, even under water. In some cases, covering the burning metal with sand can help contain the heat and sparks from the reaction. Class D extinguishing agents are available (generally as a dry powder in a bucket or box) which can be quite effective, but these agents are rare on the campus.
Potassium & Sodium
Pure metals such as potassium and sodium react violently (even explosively) with water and some other chemicals, and must be handled with care. Generally, these metals are stored in sealed containers in a non-reactive liquid to prevent decay (surface oxidation) from contact with moisture in the air.
All of these metals are not uncommon in labs on the OU campus, but are generally only found in small quantities and accidental fires and reactions can be controlled or avoided completely through knowledge of the properties of the metals and using good judgment and common sense. If you are planning a research project using a large amount of flammable metals you should consider purchasing a five or ten-pound container of Class-D extinguishing agent as a precaution.