Fire Codes and the GHS
Part 5: Flammable and Combustible Liquids
Part 5 of our series compares the International Fire Code (IFC) flammable and combustible liquid hazard classes with OSHA/GHS (Rev. 7) classifications to understand and document how they differ. Our goal in these articles is to provide the knowledge and tools necessary for code users to confidently assign the applicable fire code hazard class when the GHS hazard classes, generally available in a material’s Safety Data Sheet, are known.
Background
OSHA’s Hazard Communication (HAZCOM) Standard (29 CFR 1910.1200) prescribes the hazard classification system manufacturers are required to use to classify and label chemicals and communicate the hazards of materials in Safety Data Sheets (SDS). Appendix Table E104.2, introduced in the 2024 IFC, presents IFC hazard classes alongside those found in HAZCOM 2012, based on Revision 3 of the GHS. The much-awaited update to the HAZCOM Standard, based on Rev. 7 (2017) and some elements of Rev. 8 of the GHS, was published on May 20, 2024, and took effect on July 19, 2024. OSHA has now published some Corrections and Technical Amendments to the Final Rule, available here.
Fundamentals
There are likely no hazard classes more familiar to fire service professionals than flammable and combustible liquids. For decades, in the IFC and across NFPA standards, flammable liquids have been known as Class I liquids and combustible liquids as Class II and III liquids.
But as they say, change is good, right?
The 2024 edition of NFPA 30, Flammable and Combustible Liquids Code, introduced us to Ignitable liquids (any liquid with a closed-cup flash point). Under NFPA 30, flammable and combustible liquids are now Ignitable, although the terms and definitions for flammable and combustible liquids remain and are unchanged to help correlate across editions. Although the IFC does not refer directly to Ignitable liquids, NFPA 30 is referred to extensively throughout the Code, so it’s helpful to be aware of this change.
NFPA 704, Standard System for the Identification of the Hazards of Materials for Emergency Response, has a hazard rating system primarily to alert first responders to the relative hazards presented by materials in buildings and tanks using standardized placards. However, the NFPA 704 hazard ratings are sometimes used in the Code to specify when a code requirement applies. For this reason, the table below illustrates the NFPA 30 flammable and combustible hazard classes and how the NFPA 704 flammability hazard ratings align with those hazard classes.
The GHS and OSHA
The GHS (Rev. 7) and OSHA HAZCOM (2024) both use a single hazard class (Flammable liquids) to identify regulated liquids with a closed-cup flash point. Combustible liquids are either Class 3 or 4 Flammable liquids under this schema.
A close comparison of the hazard class definitions found in the 2024 IFC Appendix E, Table E104, reveals there are three notable differences between the GHS classifications compared to the IFC and NFPA 30:
- The 95°F boiling point cutoff for Category 1 and Category 2 Flammable liquids, which reflects the globally agreed-upon level of risk, does not directly align with the IFC and NFPA Class I Flammable liquid cutoff of (100°F),
- The GHS Flammable Liquid Category 3 flash point range includes the Class IC Flammable and Class II Combustible liquid IFC categories and
- GHS and OSHA do not classify materials with a flash point over 200°F.
Despite these differences, users can refer to Section 9, Physical and Chemical Properties, of the SDS, which generally includes a material’s flash point and boiling point to classify materials correctly.
Looking ahead
Code change proposals submitted earlier this year as part of the ICC code change process will better align the definitions of flammable and combustible liquids in the 2027 IFC with GHS and OSHA definitions. Unless the proposals are overturned at the ICC Public Comment Hearing in 2026, the 2027 IFC and GHS hazard classes will align as shown in the Comparison Table below. Until then, Code users should continue to use flash point and boiling data found in Section 9 of the SDS to classify flammable and combustible liquids.
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