“Is This Liquid Flammable?” – a Short Question with a Complex Technical and Regulatory Answer

Whether a liquid is being stored, shipped, sold or scrapped, its identity with respect to flammability hazard classification may change dramatically. The introduction of the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) has provided guidance for standardizing the classification and labeling of flammability hazards. The new classification system includes four categories distinguished by the liquid’s flashpoint and boiling point, with some caveats, including the temperature at which the liquid is used. However, across the regulatory landscape, several different definitions still exist.

Until recently, both the US Occupational Safety and Health Administration (US OSHA) and Canadian Centre for Occupational Health and Safety (CCOHS) defined two hazard categories regarding the flammability of liquids with a relatively simple distinction. A flammable liquid had a flashpoint below 100°F (37.8°C), while a combustible liquid had a flashpoint at or above 100°F (37.8°C) but below 200°F (93.3°C). A mixture was flammable unless 99 percent or more of its components had a flashpoint greater than or equal to 100°F. While US OSHA and CCOHS aligned their standards with the GHS in 2012 and 2015, respectively, other regulatory agencies have retained their own unique definitions of flammability hazards. As regulatory definitions are slow to change, so are those that have been internalized by the workforce. Much of the workforce was trained under the previous system of flammable and combustible liquids, and awareness of the new system will not come without significant education and training.

In this presentation, we review technical aspects of the current GHS flammable liquid hazard classifications, and compare them with those of the US Department of Transportation (DOT), Transport Canada, the National Fire Protection Association, the US Consumer Product Safety Commission (CPSC) and others.