OSHA's language tends to be less prescriptive and defers to other regulating bodies where they are more specific.  In this case, the applicable OSHA standard is 29 CFR 1910.106, Flammable and Combustible Liquids, which is based on NFPA (National Fire Protection Association) 30 Flammable and Combustible Liquids Code. The 1969 version of NFPA 30 is incorporated by reference and is therefore, legally enforceable by OSHA. Of course, NFPA 30 has been updated many times since 1969, so although OSHA requires employers to be in compliance with the 1969 version of NFPA 30; OSHA will also accept compliance with the most current version of NFPA 30 (and certainly that is the best way to go). 

See this page for FAQs about the NFPA 30 standard.


A flammable liquid is defined by OSHA and the National Fire Protection Association (NFPA) 30, "Flammable and Combustible Liquids Code," as any liquid with:

         a flashpoint below 100 F. (37.8 C) and

         a vapor pressure not exceeding 40 psia 100 F.

Flammable liquids are called Class 1 liquids and are divided into three groups - Class 1A, 1B and 1C - according to the degree of the hazard. Liquids with flashpoints above 100 F are called combustible.

Keep in mind that DOT has its own definitions for these same terms.


Flammable liquids are commonly further divided into three classes


Class           Flash Point                      Boiling Point                    Examples

IA               Below 73F                      Below 100 F                    Ethyl Ether

IB               Below 73 F                     At or above 100 F          Acetone, Benzene, Toluene

IC                At or above 73F and                                             Hydrazine and Styrene

below 100F


Combustible liquids are similarly divided into three classes


Class            Flash Point                      Example

II                100-139 F                      Acetic acid, naptha and stoddard solvent

IIIA           140-199 F                      Cyclohexanol, formic acid and nitrobenzene

IIIB            200 F or above              Formalin and picric acid


The flashpoint of a flammable liquid is the lowest temperature at which it can form an ignitable mixture with air and produce a flame when a source of ignition is present.


how to ground flammable liquids 

This page was updated on 16-Oct-2020