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December 2008: Flammable and Combustible Liquids

You may be trying to determine if you have any flammable or combustible liquids that need any special protection to be stored in your facility. Your first instinct may be to use flammable labels on the products themselves to determine if any flammable materials exist at your facility. Use of these labels could be misleading - especially since there are several different entities that rate flammable liquids. For example, the Occupational Health & Safety Administration (OSHA), the American National Standards Institute (ANSI), the Environmental Protection Agency (EPA), the Department of Transportation (DOT), the Consumer Protection Safety Commission (CPSC), FM Global (used to be Factory Mutual), and the National Fire Protection Association (NFPA) all have their own ways of classifying flammable and combustible liquids.

One commonality among all of these entities is that they use flash points of the liquids to determine how hazardous they are. A flash point is the temperature at which the vapor above a liquid may be ignited, but not continue to burn. Boiling points are also used with some of these classifications as well. The boiling point is the temperature at which the liquid boils. Unfortunately, these entities do not always use the same temperature cut-off points nor do they use the same verbiage for classifications of these liquids. Also, some of these entities stop classifying materials with flash points not much more than room temperature while others include any flashpoint temperature.

For example, oils have flash points above 200°F. The DOT does not classify liquids with flashpoints above 200°F. However, NFPA considers oils a Class III B liquid and has special storage requirements. Thus, if the DOT classification were used, oils would not have been identified as needing any special protection.

A Globally Harmonized System (GHS) category system was proposed in 1992 during a United Nations conference. This system was recently adopted by the European Union. However, this system is not exclusively used throughout the world. Additionally, one must be careful in not confusing these ratings with NFPA 704 ratings as the lower numbers are more hazardous with GHS and higher numbers are more hazardous with NFPA 704.

Which standards to use can be narrowed by only using entities that actually deal with fire protection in buildings. This just leaves FM Global and NFPA. The storage standards for both of these use flammable and combustible liquid determinations called out in each of their associated standards. These "liquids" are determined to be: liquids, emulsions, mixtures, and semi-solids. To be determined flammable or combustible, these must have a flash point and a fire point. The fire point is the temperature at which combustion will continue once the vapor above a liquid is ignited.

The Material Safety Data Sheet (MSDS) should be used to help obtain this information. These data sheets can be misleading as MSDS's typically list an item as flammable if a flammable liquid is present in the item. Even a small percentage of a flammable liquid used in an item could result in the item being classified as a flammable liquid. However, this item may not behave as a flammable liquid due to the low percentage of flammables present. Thus, the percentage of flammable components should be determined for each liquid. This is not always an easy task as MSDS's are not standardized and some of the components may be listed as proprietary or as trade secrets.

For example, water-based paint has some components that have flash points. Therefore, this paint has a flashpoint listed on the MSDS. However, water-based paint has a low percentage of flammable liquids and it does not burn like a flammable liquid would. Thus, water-based paint does not have any special storage requirements.

One should also use caution with just blindly using MSDS's as there are times where these data sheets are provided when a flammable liquid was used in a product that is in a solid state. For example, a thread locking liquid may have been added to a nut or bolt and then allowed to dry. A MSDS may list this as having the flash point of the thread locking liquid. However, this is in a solid state and is not considered any more hazardous that standard combustible solid materials.

MSDS's do not always provide complete information about the product. For example, water miscibility and the viscosity of the liquid are both used to help determine the design of special protection areas for flammable liquids. However, this information is not always provided on these sheets. If a liquid is water miscible, it means that this liquid will mix with water at all concentrations. Viscosity is a property of a fluid that resists fluid flow. A low viscosity liquid - such as water - will flow readily. Honey has a higher viscosity and does not flow as readily. One unit of viscosity is a centipoise (cp). Water has a viscosity of 1 cp and honey has a viscosity of 10,000 cp. Higher viscosity mixtures can result in a reduction of the fire hazard.

Additionally, the size and type of container are not listed on these sheets, but they do make a big difference in the protection needed for this storage. Plastic and glass containers are prone to failure and all of the liquids within the fire area are expected to become involved in the fire. However, metal containers can withstand the heat from fires better. Thus, a small percentage of the liquid in metal containers would be expected to become involved in the fire. For this reason, liquids in metal containers are considered easier to protect than liquids in plastic or glass containers.

Some liquids may need: a cut-off room, rated electrical equipment, ventilation, containment, automatic sprinkler protection, and drainage or a foam-water sprinkler system. Other liquids may just need to be protected by sprinklers. The amounts of each type of liquid will help to determine the most cost effective protection arrangement for your facility.

Your Loss Prevention Consultant can help you to determine if any of the storage at your facility has any special protection requirements and which protection arrangement is (or arrangements are) needed to best protect your facility.

Risk Logic, Inc. can help with determining the hazard of liquids at your facility and with determining the protection needed for these liquids.