FAQ - NFPA 30

				The definitions of "flammable liquid" and "combustible liquid" in NFPA 30 differ from those used by the U.S. Department of Transportation. Why?

				What are common examples of the various flammable and combustible liquids classified by NFPA 30?

				Is there a lower limit to the application of Chapter 2, Tank Storage?

				Tables 2.3.2.1.1 (a) and (b) and Tables 2.3.2.1.2 through 2.3.2.1.5 [Tables 2-1 through 2-6 in prior editions] impose separation distances between the tank shell and "the nearest important building on the same property". When is a building considered to be important enough that these separation distances should be imposed?

				Some safety cans have a wire mesh screen in their spouts to serve as a flame barrier; some others do not. Are these screens required?

				Some flammable liquids storage cabinets have a grounding screw. Is the cabinet required to be electrically grounded?

				Are flammable liquids storage cabinets required to have exhaust ventilation?

				How does NFPA 30 address inside container storage ares?

				Can flammable or combustible liquid be stored in a "general purpose warehouse", i.e., one that is not constructed in accordance with Chapter 4 of NFPA 30?

				Does NFPA 30 govern storage of liquids in a laboratory?




				The definitions of "flammable liquid" and "combustible liquid" in NFPA 30 differ from those used by the U.S. Department of Transportation. Why?



				Definition and classification of flammable and combustible liquids are addressed in Section 1.7 of NFPA 30. A flammable liquid is defined as a liquid whose flash point does not exceed 100°F, when tested by closed-cup test methods, while a combustible liquid is one whose flash point is 100°F or higher, also when tested by closed-cup methods. These broad groups are further classified as follows: Clas IA - Flash Point less than 73°F; Boiling Point less than 100°F Class IB - Flash Point less than 73°F; Boiling Point equal to or greater than 100°F Class IC - Flash Point equal to or greater than 73°F, but less than 100°F Class II - Flash Point equal to or greater than 100°F, but less than 140°F Class IIIA - Flash Point equal to or greater than 140°F, but less than 200°F Class IIIB - Flash Point equal to or greater than 200°F Notice that boiling point is only used to distinguish between ClassIA and Class IB. Class IA liquids are extremely volatile, but there are few liquids that are so classed. Note also that, theoretically, there is no upper limit to Class IIIB. These definitions and classifications were agreed to years ago by NFPA, the U. S. Department of Transportation (DOT), and the U. S. Occupational Safety and Health Administration (OSHA) in an attempt to remove inconsistencies in the definitions used at the time. Since then, DOT has changed its definition of "flammable liquid" by raising the upper limit to 141°F (60.5°C). This was done because the United States is a partner to a world-wide set of hazardous materials regulations sponsored by the United Nations and must use the UN definitions, at least for international transportation. Note, however, that DOT regulations include a so-called "domestic exemption" that allows a shipper to redesignate as a combustible liquid any liquid whose flash point is in the NFPA Class II range and which does not meet any other hazardous material definition.

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				What are common examples of the various flammable and combustible liquids classified by NFPA 30?



				Class IA - Diethyl Ether, Ethylene Oxide, some light crude oils Class IB - Motor and Aviation Gasolines, Toluene, Lacquers, Lacquer Thinner Class IC - Xylene, some paints, some solvent-based cements Class II - Diesel Fuel, Paint Thinner Class IIIA - Home Heating Oil Class IIIB - Cooking Oils, Lubricating Oils, Motor Oil

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				Is there a lower limit to the application of Chapter 2, Tank Storage?



				Until the 1993 edition, the answer was "no". A new definition of storage tank was added in 1993 that established 60 gallons capacity as the minimum quantity for a vessel to be considered a storage tank. This, in effect, sets a lower limit to the applicability of Chapter 2 of NFPA 30. .

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				Tables 2.3.2.1.1 (a) and (b) and Tables 2.3.2.1.2 through 2.3.2.1.5 [Tables 2-1 through 2-6 in prior editions] impose separation distances between the tank shell and "the nearest important building on the same property". When is a building considered to be important enough that these separation distances should be imposed?



				"Important Building" is defined by NFPA 30 as "a building that is considered not expendable in an exposure fire. Examples include, but are not limited to, occupied buildings, control buildings, or buildings that contain high value contents or critical equipment or supplies." Obviously, some judgement is involved in determining whether a building is important enough to warrant compliance with the separation distances. The key question becomes: "Can I really afford to lose this building or the people in the building or the contents of the building because of a fire in the tank?" Remember, the contents of a normally unoccupied building might be process control equipment critical to safe operation.

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				Some safety cans have a wire mesh screen in their spouts to serve as a flame barrier; some others do not. Are these screens required?



				The screens are not required by NFPA 30. However, some thired-party certification organizations require the screen in order to obtain listing or approval.

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				Some flammable liquids storage cabinets have a grounding screw. Is the cabinet required to be electrically grounded?



				NFPA 30 does not require that the cabinet itself be grounded. Many manufacturers provide a grounding screw on their cabinets as a convenience to the user. The user can connect this screw to a building ground and use the cabinet-mounted ground point as needed to ground individual containers from which liquids are dispensed.

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				Are flammable liquids storage cabinets required to have exhaust ventilation?



				NFPA 30 does not require an exhaust ventilation system for storage cabinets, although most cabinets have plugged fittings that can be used for such purpose. Exhaust ventilation should only be provided when warranted by the materials in the cabinet, for example for particularly toxic or noxious materials. If provided the manufacturer's instructions should be followed. Typically, this will involve small diameter steel duct or pipe leading directly and by the shortest route to the exterior of the building. Exhaust must be taken from the bottom of the cabinet.

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				How does NFPA 30 address inside container storage ares?



				Chapter 4 of NFPA 30 describes four types of inside liquid storage areas: inside rooms, which have no exterior walls; cut-off rooms, which have either one or two exterior walls; attached buildings, which share only one wall with another structure; and liquid warehouses, which are either separate buildings entirely or which are separated by 4-hour construction from adjoining areas. Inside rooms are limited to 150 sq. ft., if of 1 hour construction. If of 2-hour construction, they can be as large as 500 sq. ft. Cut-off rooms and attached buildings are limited to 300 sq. ft., if of 1-hour construction, but can be any size desired, if of 2-hour construction. However, NFPA 30 sets a maximum limit on the total quantity of liquid that can be stored in a cut-off room or attached building, in accordance with Table 4-4.4.1, if a fire protection system is not provided or if the fire protection system cannot meet the criteria imposed by Section 4-8 of NFPA 30.

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				Can flammable or combustible liquid be stored in a "general purpose warehouse", i.e., one that is not constructed in accordance with Chapter 4 of NFPA 30?



				Yes, but the warehouse must be protected in accordance with NFPA 13 for 20-foot high storage of Class IV commodity. In addition, there are severe restrictions on maximum container size, maximum storage height, and maximum total quantity stored. This is all covered in Section 4-5.2 of NFPA 30.

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				Does NFPA 30 govern storage of liquids in a laboratory?



				In the open work area of the laboratory, no. The quantity of liquid allowed in a laboratory work area is governed by NFPA 45, Standard on Fire Protection for Laboratories Using Chemicals. However, NFPA 30, would cover an inside storage room in a laboratory occupancy, but must be separated from adjoining building areas by 2-hour construction.

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