What is Aerosol Fire Protection
The purpose of this article is to provide an overview of the storage, display, handling, and usage of aerosols with the related fire protection requirements, when they are applicable, and how to apply them.
What is an aerosol? Most commonly, aerosols are encountered as a cooking spray product that is used to facilitate cooking operations, both domestically and commercially. However, for fire protection and fire code applications, the definitions within these codes most be adhered to in order to properly store, use, and display aerosol products. The most commonly used model fire code within the United States is the International Fire Code (IFC), published by the International Code Council (The International Code Council, 2017). For the purposes of this article, the 2018 Edition of this code will be referenced. Section 202 of the IFC defines aerosols and related terms as follows:
Aerosol Container: A metal can or plastic container up to a maximum size of 33.8 fluid ounces or a glass bottle up to a maximum size of 4 fluid ounces designed and intended to dispense an aerosol.
Aerosol, Cooking Spray Products: Aerosol cooking spray products are those aerosol products designed to deliver a vegetable oil or a solid or nonflammable liquid to reduce sticking on cooking and baking surfaces, or to be applied to food, or both. These products have a chemical heat of combustion that is greater than 8600 btu/lb and contain no more than 19 percent by weight of flammable propellant.
Aerosol Product: A combination of container, a propellant and a material that is dispensed. Aerosol products shall be classified by means of the calculation of their chemical heats of combustion and shall be designated Level 1, Level 2, or Level 3.
Level 1 Aerosol Products: Those with a total chemical heat of combustion that is less than or equal to 8600 btu/lb
Level 2 Aerosol Products: Those with a total chemical heat of combustion that is greater than 8600 btu/lb but less than or equal to 13,000 btu/lb.
Level 3 Aerosol Products: Those with a total chemical heat of combustion that is greater than 13,000 btu/lb.
Aside from the IFC, the other primary resource in applying fire protection requirements to aerosols is NFPA 30B: Code for the Manufacture and Storage of Aerosol Products (The National Fire Protection Association, 2014). The IFC dictates when protection, storage, and other measures are necessary. These requirements are outlined in Chapter 51: Aerosols. The designer then must classify the aerosols according to the definitions listed above: aerosols: cooking spray products, Level 1, Level 2 or Level 3. A cooking spray aerosol must exactly meet the definition listed above. The other aerosols must be classified according to their heats of combustion.
Heat of Combustion
The heat of combustion is the amount of energy released per unit weight of a combustible material. For example, dry wood has a heat of combustion of around 7,000 btu/lb. In contrast, the heat of combustion of gasoline is around 20,500 btu/lb. Practically, this means that one would need about three pounds of wood to provide as much heat as one pound of gasoline. This also means that, the higher the heat of combustion of a material is, the more hazardous it is from a fire and life safety standpoint.
Classifying Aerosols
Almost all aerosols will have a Safety Data Sheet (SDS, formerly called Material Safety Datasheet) where the hazards of the aerosols are listed—fire hazards and other, general health hazards. Within the SDS, the classification of the aerosol may be directly stated as “Level 1,” “Category 1,” or so forth. It is less common to have the heat of combustion of the aerosol listed, so the SDS can be directly used to classify the aerosol. Consider the SDS at: https://www.rustoleum.com/MSDS/ENGLISH/7779830.pdf This aerosol is listed as “Flammable Aerosol, Category 1,” which would equate to a Level 1 Aerosol in the IFC. If a critical, exact classification is necessary, further research will be required to determine the heat of combustion of the aerosol in order to classify it. The manufacturer of the aerosol will most likely have this information, and may need to be contacted in order to retrieve it.
Aerosol Storage and Fire Protection
Chapter 51 of the IFC must next be consulted to determine the storage and fire protection requirements of aerosols. This Chapter not only references fire protection requirements and details, but also the storage amounts, heights, and arrangements of aerosols. The requirements also vary depending on if the aerosols are stored in a retail display, or even if they are stored adjacent to flammable liquids. A simple example of determining protection requirements are found in Section 5104.1 of the IFC[1]. This section states that a Level 1 Aerosol shall be treated as a Class III commodity and be protected in accordance with NFPA 13: Standard for the Installation of Sprinkler Systems. A Class III commodity is essentially wood and wood products. Fire protection of a Level 1 Aerosol would be required if it was stored greater than 12 feet in height, and the fire sprinkler requirements would be determined by applying the sprinkler standard, NFPA 13.
Table 5104.3.2 of the IFC prescribes requirements for inside, dedicated storage of Level 2 and 3 aerosols in general purpose warehouses. By dedicated storage, the code means that no other types of material will be stored with the aerosols (the requirements are different in that case). This table directs the reader to NFPA 30B for fire protection requirements[2]. The 2015 Edition of this standard will be discussed herein.
Chapter 6 of NFPA 30B contains the fire protection requirements of Level 2 and 3 aerosols. This chapter contains criteria for the automatic sprinkler systems required to protect these aerosols, and also cross references certain aerosols to be protected as general storage commodities. For example, Section 6.4.1.1.1 of NFPA 30B considers Level 2 aerosols with a net weight in containers less than 1 oz equivalent to cartooned, unexpanded Group A plastics. This is similar to how Level 1 aerosols are to be considered equivalent to Class III commodities. A more general knowledge of high piled combustible storage and storage type sprinkler systems is necessary to fully understand and develop fire protection requirements for aerosols.
Section 6.4.2.7 of NFPA 30B lists a number of protection schemes and requirements for the storage of aerosols. Figure 1 below is an excerpt of one of these tables.
Figure 1: Table 6.4.2.7(b) of NFPA 30B-15
For a Level 2 aerosol stored directly on the ground (no racks) or on pallets, within cartons, in a warehouse with a 25 foot high ceiling, with aerosols stored up to 20 feet high, an Early Suppression Fast Response (ESFR) sprinkler system with K14 pendent sprinkler heads, operating at 50 psi, with 12 sprinklers operating, and with a hose stream allowance of 250 gpm for 1 hour, is required to accommodate such storage.
Similar details are present within the rest of the tables in Section 6.4.2.7 and other cases of fire protection are within Chapter 51 of the IFC and NFPA 30B. The determination of fire protection is extremely complex and requires expertise in high piled combustible storage, storage type sprinkler systems, Chapters 32 and 51 of the IFC, NFPA 13, and NFPA 30B. A licensed fire protection engineer or NICET IV in Water-Based Systems should be consulted to determine the fire protection requirements for aerosols.
In summary, the following is necessary to determine aerosol fire protection requirements:
- Classification of the aerosol product(s)
- Determination of the storage quantity, arrangement, location, and other details of aerosol storage
- Consult Chapter 51 of the IFC for fire protection requirements and other requirements
- Utilize NFPA 30B or NFPA 13 to determine fire sprinkler protection requirements
- Apply Chapter 32: High Piled Combustible Storage requirements, which are related to storage arrangement and not direct fire protection criteria
[1] The 2018 IFC may be accessed online at no charge at https://codes.iccsafe.org/content/IFC2018
[2] NFPA 30B may be accessed online at no charge at https://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=30B