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September 2009: Flammable and Combustible Liquids

When trying to determine what liquids need to go into your flammable liquids room, you may be tempted to use the flammable liquid labels that are on some of the liquid containers. However, this mistake could result in these liquids not being properly protected at your facility. This is due to the fact that these labels are DOT labels used for transporting these liquids rather than storing these liquids.

The DOT defines flammable liquids as liquids having a flash point of 140°F or less and combustible liquids of having a flash point between 141°F and 200°F. The DOT further breaks down flammable liquids into packing groups. Packing Group I is liquids with boiling points below 95°F. Packing Group II is liquids with flash points below 73°F and boiling points above 95°F. Packing Group III is liquids with flash points of 140°F or less and boiling points above 95°F.

NFPA 30 defines a flammable liquid as any liquid that has a closed-cup flash point below 100°F and a combustible liquid as any liquid that has a closed-cup flash point at or above 100°F. Flammable liquids are further broken down into: Class IA (any liquid with a flash point below 73°F and a boiling point below 100°F), Class IB (any liquid with a flash point below 73°F and a boiling point at or above 100°F), and Class IC (any liquid that has a flash point at or above 73°F but below 100°F). Combustible liquids are further broken down into: Class II (any liquid that has a flash point at or above 100°F but below 140°F), Class IIIA (any liquid that has a flash point at or above 140°F but below 200°F), and class IIIB (any liquid that has a flash point at or above 200°F).

FM Global considers all liquids with measurable flashpoints and fire points as flammable liquids. FM Global does not classify any liquids as combustible. However, FM Global does break the flammable liquids into categories with flash points less than 200°F and with flashpoints equal to or greater than 200°F for protection purposes.

In order to properly protect these liquids stored or used in a building, NPFA or FM Global standards will need to be used. The liquid definitions associated with each standard must also be used. Since DOT definitions do not include liquids with flash points above 200°F, these liquids would have been missed if just the DOT labels were being used.

Other factors such as: viscosity, the percent of flammable components within the liquid, water miscibility, material of the container, specific gravity (liquid will float on water or water floats on the liquid), the size of the container, etc. also play a role into how these liquids should be protected. Some items - such as bolts with a dried on thread locking compound - have flashpoints listed on the material safety data sheet (MSDS), but do not need to be in a flammable liquids room. This is due to this not being a liquid. While other items - such as oils - will not have DOT labels for flammable or combustible liquids, but may still need to be stored in flammable liquids room.

Risk Logic, Inc. can help you determine your protection needs for flammable and combustible liquids at your facility. Please contact us for assistance.