FAQs

  • What are two of the most important factors defining the fire risk associated with containerized storage of flammable and combustible liquids?

    These factors include certain liquid properties and the container type and size.

  • Can you explain what these liquid properties are?

    There are a number of liquid properties including physical, ignition, combustion and reactivity of the material that define the hazards. The NFPA has selected flash point and with some materials, the boiling point, to rank a given liquid’s fire risk.

    National Fire Protection Association. (2018). NFPA 30: Flammable and Combustible Liquids Code, Chapter 4: Definition and Classification of Liquids, section 4.2: Definitions Specific to Chapter 4.

  • How does the NFPA method categorize flammable and combustible liquids?

    The NFPA liquid classifications are based upon the liquids flash point and boiling point as follows:

    NFPA Liquid Classification Flash Point Boiling Point
    Class IA Flammable Liquid < 73oF (22.8oC) < 100oF (37.8oC)
    Class IB Flammable Liquid < 73oF (22.8oC) ≥ 100oF (37.8oC)
    Class IC Flammable Liquid ≥ 73oF (22.8oC) & < 100oF (37.8oC)
    Class II Combustible Liquid ≥ 100oF (37.8oC) & < 140oF (60oC)
    Class IIIA Combustible Liquid ≥ 140oF (60oC) & < 200oF (93oC)
    Class IIIB Combustible Liquid ≥ 200oF (93oC)


    National Fire Protection Association. (2018). NFPA 30: Flammable and Combustible Liquids Code, Chapter 4: Definition and Classification of Liquids, section 4.3: Classification of Liquids.

  • What role does container type and size play when defining fire risk?

    There are two issues to consider including ignition potential and container performance under fire conditions.

    When filling flammable liquids into containers made from any material, the risk of electrostatic ignition must be understood and managed. The risk is highest with hydrocarbons being filled into plastic containers. This is due to the fact that these liquid and container types are both non-conductive and can accumulate an electrostatic charge.

    Regarding container performance under fire conditions, metal containers retain their integrity better in comparison to plastic containers. However, metal containers can over-pressurize and rupture when exposed to fire. The likelihood of this occurring can be significantly reduced by using a relieving-style container.

    Plastic containers will melt and release their ignitable contents when exposed to fire. Plastic containers filled with certain liquids, such as hydrocarbons, are subject to permeation of the product into the container walls. Certain treatments such as fluorination can reduce the permeation rate of the lading thus enhancing the integrity of the container. However, the use of fluorinated plastics is not widespread.

    Generally speaking, fires involving smaller containers are easier to control with fire sprinkler systems.

  • What is a relieving-style container?

    NFPA 30 defines a relieving-style container as a “metal container, a metal intermediate bulk container, or a metal portable tank that is equipped with at least one pressure-relieving mechanism at its top that is designed, sized and arranged to relieve the internal pressure generated due to exposure to fire so that violent rupture is prevented.”

    National Fire Protection Association. (2018). NFPA 30: Flammable and Combustible Liquids Code, Chapter 16: Automatic Fire Protection for Inside Liquid Storage Areas, section 16.2.3: Relieving-Style Containers.

  • Can you advise how many fusible (plastic) plugs are required for 55 gal. steel drums if they are to be considered “relieving-style?”

    Paragraph 16.5.1.7 in NFPA 30 states “When relieving-style containers are used, both 3⁄4 in. (20 mm) and 2 in. (50 mm) listed and labeled pressure-relieving mechanisms are required on containers greater than 6 gal. (23 L) capacity.”

    Furthermore, when fusible (plastic) plugs are used with 55 gal. steel drums, they “shall be listed and labeled in accordance with FM Global Approval Standard for Plastic Plugs for Steel Drums, Class Number 6083, or equivalent,” per paragraph 16.3.6 in NFPA 30.

    National Fire Protection Association. (2018). NFPA 30: Flammable and Combustible Liquids Code, Chapter 16: Automatic Fire Protection for Inside Liquid Storage Areas, sections 16.3: general Requirements and 16.5: Fire Protection System Design Criteria.

  • Does NFPA 30 permit the packaging and storage of flammable and combustible liquids in plastic and composite containers?

    NFPA 30 does allow for this and specifies the plastic or composite container type and maximum container size for the various NFPA liquid classifications.

    National Fire Protection Association. (2018). NFPA 30: Flammable and Combustible Liquids Code, Chapter 9: Storage of Liquids in Containers – General Requirements, section 9.4: Acceptable Containers.

  • Can you provide more detail on permitted plastic and composite container type and maximum container size?

    Table 9.4.3, NFPA 30 provides specific provisions for plastic and composite containers as follows:

    Container Type Class IA Class IB Class IC Class II Class IIIA
    Rigid Plastic IBCs (UN 31H1 or 31H2) & Composite IBCs with Rigid Inner Receptacle (UN31HZ1) NP NP NP 793 gal. 793 gal.
    Composite IBCs with Flexible Inner Receptacle (UN31HZ2) and DOT/UN-Approved Flexible IBCs NP NP NP NP NP
    Polyethylene UN1H1 and UN1H2, or as Authorized by DOT Exemption 1.3 gal. 5.3 gal. 5.3 gal. 119 gal. 119 gal.

    NP = Not Permitted (unless an accepted fire protection system is provided and protection against static electricity ignition)

    It should also be noted that per paragraph 9.4.3.1 Class IB and Class IC liquids that are water-miscible shall be permitted to be stored in plastic containers up to 60 gal (230 L) in size, if stored and protected in accordance with Table 16.5.2.7.

    National Fire Protection Association. (2018). NFPA 30: Flammable and Combustible Liquids Code, Chapter 9: Storage of Liquids in Containers – General Requirements, section 9.4: Acceptable Containers.

  • What are the limits for metal containers?

    Table 9.4.3, NFPA 30 also provides specific provisions for metal containers as follows:

    Container Type Class IA Class IB Class IC Class II Class IIIA
    Metal (other than drums) 1.3 gal. 5.3 gal. 5.3 gal. 5.3 gal. 5.3 gal.
    Metal drum (e.g., UN 1A1/1A2) 119 gal. 119 gal. 119 gal. 119 gal. 119 gal.
    Approved metal portable tanks and IBCs 793 gal. 793 gal. 793 gal. 793 gal. 793 gal.


    National Fire Protection Association. (2018). NFPA 30: Flammable and Combustible Liquids Code, Chapter 9: Storage of Liquids in Containers – General Requirements, section 9.4: Acceptable Containers.

  • In addition to permitted container type and maximum container size, does NFPA 30 have other provisions related to the storage conditions of these containers?

    NFPA has additional provisions for these containers under the categories of “unprotected storage” and “protected storage.”

    National Fire Protection Association. (2018). NFPA 30: Flammable and Combustible Liquids Code, Chapter 12: Storage of Liquids in Containers – Storage Occupancies, section 12.3: General Requirements.

  • Can you explain the difference between “unprotected storage” and “protected storage?”

    “Unprotected storage” assumes, in the event of a fire, an uncontrollable fire would be expected to occur, regardless of the installed fire protection system. Given this, NFPA 30, Table 12.6.2.2 has quantity limits for “unprotected storage” of plastic and composite containers as follows:

    Liquid Class Plastic Containers Rigid Nonmetallic IBCs and Composite IBCs
    Maximum Storage Height (ft.) Maximum Total Quantity per Pile or Rack Section (gal.) Maximum Total Quantity (gal.) Maximum Storage Height (ft.) Maximum Total Quantity per Pile or Rack Section (gal.) Maximum Total Quantity (gal.)
    IA 5 660 660 NP NP NP
    IB 5 1,375 1,375 NP NP NP
    IC 5 2,750 2,750 NP NP NP
    II 10 4,125 8,250 7 4,125 8,250
    IIIA 15 13,750 27,500 7 13,750 27,500
    IIIB 15 13,750 55,000 7 13,750 55,000

    NP = Not Permitted

    Additionally, Table 12.6.2.2 has quantity limits for “unprotected storage” of metal containers as follows:

    Liquid Class Metal Containers Metal Portable Tanks and Metal IBCs
    Maximum Storage Height (ft.) Maximum Total Quantity per Pile or Rack Section (gal.) Maximum Total Quantity (gal.) Maximum Storage Height (ft.) Maximum Total Quantity per Pile or Rack Section (gal.) Maximum Total Quantity (gal.)
    IA 5 660 660 NP NP NP
    IB 5 1,375 1,375 7 2,000 2,000
    IC 5 2,750 2,750 7 4,000 4,000
    II 10 4,125 8,250 7 5,500 11,000
    IIIA 15 13,750 27,500 7 22,000 44,000
    IIIB 15 13,750 55,000 7 22,000 88,000

    NP = Not Permitted

    “Protected storage” means an uncontrollable fire would not be expected and requires that storage height and configuration, as well as sprinkler system design is in accordance with provisions in Chapter 16, NFPA 30.

    National Fire Protection Association. (2018). NFPA 30: Flammable and Combustible Liquids Code, Chapter 12: Storage of Liquids in Containers – Storage Occupancies, section 12.6: Maximum Allowable Quantities and Maximum Storage Heights.

    It should be noted there are no quantity limitations for “protected storage.” There are a number of tables in Chapter 16: (Automatic Fire Protection for Inside Liquid Storage Areas) specific for “protected storage” of metal containers, plastic containers and rigid plastic IBCs.

  • Why are flammable liquids not permitted in plastic and composite or non-metallic intermediate bulk container IBC's, yet are allowed in plastic 55 gal. drums per NFPA 30?

    Flammable liquids, particularly hydrocarbons which are considered non-conductive liquids, are capable of ignition from an electrostatic discharge.

    Splash-filling of flammable liquids into metallic and non-metallic containers and vessels has been the cause of numerous fires via electrostatic discharge.

    When filling plastic containers with non-conductive liquids, this risk is magnified.  It is very difficult, if not impossible, to completely dissipate an electrostatic charge when filling plastic containers with non-conductive liquids.

    Therefore, the NFPA 30 committee has drawn a distinction between plastic 55 gal. drums and non-metallic IBC’s.  Given the larger volume and typically longer fill time associated with intermediate bulk containers, the committee took this higher risk into consideration when making this decision.  As a general rule, the potential for electrostatic generation, accumulation, and discharge is higher with non-metallic IBC’s.

    It should also be noted, the U.S. Department of Transportation and the United Nations allow for certain flammable liquids, including hydrocarbons, to be shipped in ordinary, unlisted nonmetallic intermediate bulk containers.

    National Fire Protection Association. (2018). NFPA 30: Flammable and Combustible Liquids Code, Chapter 12: Storage of Liquids in Containers – Storage Occupancies, section 12.6: Maximum Allowable Quantities and Maximum Storage Heights.

  • Can you advise on the most significant change in the 2018 edition of NFPA 30 related to containerized storage?

    The most significant change in the 2018 edition of NFPA 30 affects plastic and composite, or non-metallic, intermediate bulk containers (IBC’s).

    The new text in paragraph 9.4.3.2 states, “*Nonmetallic intermediate bulk containers shall be listed and labeled in accordance with UL 2368, Standard for Fire Exposure Testing of Intermediate Bulk Containers for Flammable and Combustible Liquids, FM Class 6020, Approval Standard for Intermediate Bulk Containers, or an equivalent test procedure.”

    In prior editions of NFPA 30, only combustible liquids in intermediate bulk containers stored as “protected storage” were required to be listed and labeled in accordance with UL 2368, FM Class 6020, or an equivalent test procedure.

    Given this change, all intermediate bulk containers whether it is considered “unprotected storage” or “protected storage” are required to be listed and labeled in accordance with UL 2368, FM Class 6020, or an equivalent test procedure.

    National Fire Protection Association. (2018). NFPA 30: Flammable and Combustible Liquids Code, Chapter 9: Storage of Liquids in Containers – General Requirements, section 9.4: Acceptable Containers.Why

NFPA30 may be accessed for free at www.nfpa.org/codes-and-standards/document-information-pages?mode=code&code=30. You will be asked to create a free profile to access the document in read-only format. To do so, visit www.nfpa.org/Login.

The information above is intended to provide interpretative and authoritative information as a service to our members and has been offered in good faith based on the information provided to us. We do not guarantee the accuracy or completeness of any such interpretation or information.