What are flammable and combustible materials?
Flammable materials can be found as solids, liquids, or gases.
Flammable solids can be classified in three categories: desensitized explosives, self-reactive materials, and readily combustible solids. These are generally non-explosive but may ignite when exposed to friction, moisture, heat retained from processing, or a spontaneous chemical change. More detailed information can be found from the US Department of Transportation (DOT) in 49 CFR 173.124. Examples include dust and powders.
Flammable gases are compressed gases which ignite at 14.7 pounds per square inch (psi), or can ignite at 14.7 psi when mixed with 13% or less by volume with air. Examples include butane, acetylene, methane and hydrogen.
Flammable liquids are identified as liquids that have a flashpoint (minimum temperature needed for the liquid to produce a vapor with enough of a concentration to ignite) below 100 degrees Fahrenheit (F). There is an exception to this definition. If any of the components of the mixture have flashpoints of 100 deg. F or higher, then the material is classified as combustible rather than flammable. Another way to identify flammable liquids is by class. It is important to remember that with flammable liquids that it is the vapor coming off of the liquid that will ignite and burn, not necessarily the liquid itself.
Class IA liquids have flashpoints below 73 degrees F and boiling points below 100 degrees F,
Class IB liquids have flashpoints below 73 degrees F and boiling points at or above 100 degrees F, and
Class IC liquids have flashpoints at or above 73 degrees F and below 100 degrees F. Examples include alcohols, acetone, gasoline, solvents, paint thinners, wood stains and spray paints.
Combustible materials can be found as solids or liquids.
Combustible solids have the capability of igniting and burning. Examples include wood and paper.
Combustible liquids have a flashpoint at or above 100 degrees F but below 200 degrees F. This definition does not include mixtures containing one or more components with a flashpoint at or above 200 degrees F. This group of liquids can also be identified by class.
Class II liquids have flashpoints at or above 100 degrees F and below 140 degrees F,
Class IIIA liquids have flashpoints at or above 140 degree F and below 200 degree F, and
Class IIIB liquids have flashpoints at or above 200 degree F. Examples include diesel fuel, kerosene, oil-based paints and furniture polish.
When surveying your workplace, do you notice containers of flammable or combustible materials on shelves, on countertops, or on top of flammable and combustible material storage cabinets? What about the storage cabinets? Are they in good condition, have they been re-painted, or have items been attached to the cabinet doors through the metal? While these situations appear quite frequently in the workplace, these hazardous practices should be discontinued immediately to prevent employees from being exposed to greater danger.
According to OSHA/VOSH 29 CFR 1910.106, flammable and combustible liquids are to be stored in approved containers. Additionally, the flammable and combustible storage containers should be constructed according to specifications outlined by OSHA/VOSH, DOT, and National Fire Protection Agency (NFPA), or American National Standards Institute (ANSI). All storage containers, cabinets, and rooms should have warning labels identifying the flammability hazard and should identify the area as a “NO SMOKING” area. Work activities that could potentially create sparks should also be prohibited in these storage areas.
Flammable and combustible material storage options include:
Refrigerators: Do not use domestic refrigerators/freezers for flammable or combustible liquid storage. The internal components could cause a spark and ignite the contents. Make sure the unit is explosion-proof or laboratory safe and indicate that it is to be used for flammable material only.
Safety Cans: Must contain a spring closing lid and spout cover and must be five gallons or less. This design allows safe relief of pressure when exposed to fire conditions.
Flammable and Combustible Liquid Storage Cabinets: Should be equipped with two vents on opposite sides of the cabinet (usually top right and bottom left) to protect contents from external fires. All contents should be in closed containers. If the cabinet begins to deteriorate, replace it. Do not repaint or make repairs to the cabinet. Once the structural integrity is altered, there is no guarantee that the unit will be able to protect the contents from creating greater damage in the event of a fire or explosion.
Storage Rooms: Make sure the room is equipped with explosion-proof electrical fixtures. The room should also be properly ventilated. Provide emergency spill cleanup equipment and proper cleanup training to specific employees.
Before storing any flammable or combustible materials make sure the chemicals to be stored together are compatible. Information about chemical compatibility can be located on the material safety data sheet (MSDS) for each chemical. Incompatible chemicals should be separated by an appropriately rated fire wall/partition. Be sure there are enough properly sized and appropriate types of fire extinguishers in the area and that employees are trained and understand how and when to use them.
How much is too much?
Follow this good rule of thumb: Do not store more flammable or combustible material than will be used in a reasonable amount of time. OSHA/VOSH 29CFR 1910.106 (e)(2)(ii)(b) indicates that no more than 25 gallons of Class IA liquids in containers; 120 gallons of Class IB, IC, II, or III liquids in containers; or 660 gallons of Class IB, IC, II, or III liquids in a single portable tank should be stored outside of an inside room or storage cabinet in a building. NFPA also has established guidelines found in NFPA 30, Flammable and Combustible Liquids Code. If the quantity exceeds those limits, alternate storage is required. Utilize the storage options previously discussed.
In Case of Emergency
The emergency procedures and tools vary for each class and type of flammable or combustible substance. Class B fire extinguishers should be used for flammable or combustible liquids. Class D fire extinguishers are the best defense for fires involving flammable solid materials. Sand can also be used to smother this type of fire. Make sure all emergency spill and evacuation plans are up to date and that employees have been trained. Make sure that sprinklers are not installed in chemical storage buildings used to store water-reactive materials. Sprinklers, installed according to NFPA standards, can be used in areas storing flammable or combustible liquids only.
Safety Tips/Best Practices
Here are a few safety tips and best practices to consider when evaluating, inspecting, or creating flammable and combustible material storage areas.
- Do not mix incompatible chemicals (read labels, MSDSs, etc.).
- Keep a container of sand or a class D rated fire extinguisher near work areas containing flammable and combustible solids.
- Keep ignition sources such as cigarettes, open flames, static, sparks, or hotplates away from flammable and combustible material storage and work areas.
- Make sure the fire protection system is appropriate for the type of chemical being stored (sprinkler, water spray, carbon dioxide, etc.).
- Separate flammable and combustible materials from other storage items to prevent greater damage should an explosion or fire occur.
- Make sure water reactive chemicals are not stored in areas protected by sprinklers
- Provide emergency eyewash/showers in chemical storage areas.
- Use OSHA’s flammable and combustible materials check list to survey the work area for hazards.
Taking steps to protect employees and the workplace from an unexpected catastrophe from improperly stored flammable and combustible materials may seem like a massive undertaking, but in the long run the benefits clearly outweigh the cost, time, and effort.
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