A chemical that meets the definition of “flammable” requires special precautions in handling, use, transfer, and storage. But the Occupational Safety and Health Administration (OSHA) has changed the definition of “flammable” throughout its general industry and construction standards to align them with the Globally Harmonized System of Classification and Labelling of Chemicals (GHS).

Most employers are by now aware of the changes to OSHA’s Hazard Communication Standard (29 CFR 1910.1200) that resulted when the Standard was aligned with GHS. But other OSHA standards regulating hazardous chemicals were also revised to align with GHS. Changes to the definitions of flammable and liquids affected not only the Hazard Communication Standard but also the Flammable and Combustible Liquids Standard (29 CFR 1910.106), which is now simply titled Flammable Liquids.

Old vs. New

Before the above-referenced Standards was aligned with GHS, 29 CFR 1910.106 gave the below definitions for flammable and combustible liquids:

  • Flammable Liquid: “Any liquid having a flash point below 100°F”
  • Class IA Liquids: Flash points below 73°F and boiling points below 100°F.
  • Class IB Liquids: Flash points below 73°F and boiling points above 100°F.
  • Class IC Liquids: Flash points at or above 73°F and below 100°F.
  • Combustible Liquid: “Any liquid with a flashpoint between 100°F and 200°F”
  • Class II Liquids: Flash points at or above 100°F and below 140°F.
  • Class IIIA Liquids: Flash points at or above 140°F and below 200°F.
  • Class IIIB Liquids: Flash points at or above 200°F. When these chemicals were heated within 30°F of their flash points, they were treated as Class IIA liquids.

Under GHS, all liquids with a flash point of not more than 199.4°F are categorized as flammable liquids. Flammable liquids are now further subdivided into the below categories:

  • Category 1 Liquids: Flash points below 73.4°F and boiling points at or below 95°F.
  • Category 2 Liquids: Flashpoints below 73.4°F and boiling points above 95°F.
  • Category 3 Liquids: Flashpoints at or above 73.4°F and at or below 140°F. When Category 3 liquids with flash points at or above 100°F are heated for use to within 30°F of their flash point, they must be handled in accordance with the requirements for a Category 3 liquid with a flashpoint below 100°F.
  • Category 4 Liquids: Flash points above 140°F and at or below 199.4°F. When Category 4 flammable liquids are heated for use to within 30°F of their flash points, they must be handled in accordance with the requirements for a Category 3 liquid with a flashpoint at or above 100°F.
  • In addition, the new rules specify that when a liquid with a flash point greater than 199.4°F is heated for use to within 30°F of its flash point, it must be handled in accordance with the requirements for a Category 4 flammable liquid.

See the table for an approximate comparison of the classes and categories. Note that GHS primarily uses the metric system as its standard of measurement (although it retains 100°F as a cutoff point), so the cutoff temperatures do not match up exactly between the two systems.

<73.4°F
(23°C)		 <100°F
(37.8°C)		 <140°F
(60°C)		 <199.4°F
(93°C)		 >199.4°F
(93°C)
Old 1910.106 Flammable Combustible
Classes IA, IB IC II IIIA IIIB
New
GHS		 Flammable
      Categories 1,2 3 4

Storage Requirements

As you can see, OSHA now calls all liquids with a flash point below 199.4°F “flammable liquids.” The term “combustible liquids” is no longer used. The good news is that the storage requirements found in 29 CFR 1910.106 have not, in fact, changed.

The main effect of the change to the standards is to make the wording slightly more cumbersome. “Category 3” under GHS encompasses what OSHA previously called “Class IC” and also “Class II,” taking in flammable and combustible liquids with flash points up to 140°F, but the break point for many storage requirements is 100°F. So the standard now has different requirements for “Category 3 flammable liquids with a flashpoint below 100°F,” (flammable liquids that were formerly Class IC) and “Category 3 flammable liquids with a flashpoint at or above 100°F,” (formerly Class II combustible liquids), but they are the same standards as before, just reworded for consistency with GHS hazard categories.

For more information or assistance with your Environmental and Health & Safety regulatory compliance needs, contact Ralph Carito at Total Environmental & Safety, LLC (Total) at rcarito@TotalEnviron.com or 908-442-8599.