How do "flammable" and "combustible" liquids differ according to TDG?

The distinction between "flammable" and "combustible" liquids is primarily based on their flash points, which are the minimum temperatures at which they can form ignitable mixtures with air. Flammable liquids have lower flash points, generally below 37.8 degrees Celsius (100 degrees Fahrenheit), making them capable of igniting easily at room temperature or even colder conditions. This means they pose a higher risk of fire and must be handled with greater caution. In contrast, combustible liquids have higher flash points, typically at or above 37.8 degrees Celsius, indicating they require a greater level of heat energy to ignite. This fundamental difference in ignition temperature is crucial for classifying these liquids in terms of their dangers during transport and handling, impacting safety protocols and transport regulations.

The correct differentiation allows for a better understanding of how to manage these hazardous materials safely. Knowing that flammable liquids require lower temperatures for ignition informs transporters and handlers about the necessary precautions to take, such as temperature controls and segregation from ignition sources.