Do Class 3 Flammable Liquids Not Actually Catch Fire?
To some, flammable liquids might be considered a bit of a misnomer. The liquid itself does not actually ignite.
Why call it flammable liquid? Because—the material poses a hazard in transportation when in a state it could reasonably reach during transportation.
For example, Gasoline (UN 1203) is a Class 3 flammable liquid and hazardous material.
The “flash point” (the temperature at which a material’s vapors will ignite and keep burning) of gasoline is 45°F below zero or -45°F. Very few places on earth reach temperatures that cold, so temperatures are typically above gasoline’s flash point.
Under the Hazardous Materials Regulations (HMR), a liquid with a flash point at or below 140°F is a Class 3 flammable liquid. The lower a material’s flash point is, the greater the risk of a fire involving the material.
Given that gasoline has a flash point of -45°F—approximately 185 degrees lower than the threshold for a material to be classified as a flammable liquid—it becomes clear how significant a hazard it can pose during transportation, even though the liquid itself does not catch fire.
A variety of different test procedures can be used to determine a material’s flash point. US DOT provides a list of authorized flash point test procedures for different liquids in 49 CFR 173.120(c)(i) and (ii).
Professionals use one of two methods to conduct the test—open-cup or closed-cup. Open-cup tests yield flash points a few degrees higher than a closed-cup test. The tests conducted with a closed-cup apparatus produce the more accurate and reproducible results.
For hazmat air and vessel shippers, Lion offers courses that cover the additional IATA DGR and IMDG Code requirements.
Hazmat Air Shipper Certification (IATA)
Hazmat Vessel Shipper Certification (IMDG)
Find hazmat training for managers and employees with any experience level or job description at Lion.com/Hazmat.
Why call it flammable liquid? Because—the material poses a hazard in transportation when in a state it could reasonably reach during transportation.
For example, Gasoline (UN 1203) is a Class 3 flammable liquid and hazardous material.
The “flash point” (the temperature at which a material’s vapors will ignite and keep burning) of gasoline is 45°F below zero or -45°F. Very few places on earth reach temperatures that cold, so temperatures are typically above gasoline’s flash point.
Under the Hazardous Materials Regulations (HMR), a liquid with a flash point at or below 140°F is a Class 3 flammable liquid. The lower a material’s flash point is, the greater the risk of a fire involving the material.
Given that gasoline has a flash point of -45°F—approximately 185 degrees lower than the threshold for a material to be classified as a flammable liquid—it becomes clear how significant a hazard it can pose during transportation, even though the liquid itself does not catch fire.
How to Test Flash Point
A flash point test works like this: The tester places a specified quantity of the liquid at a low temperature in a receptacle. Then they heat the material slowly. Periodically, a small flame is brought near the surface of the liquid. The tester notes the lowest temperature at which they observe a ”flash” or ignition of vapor. That is the material’s flash point.A variety of different test procedures can be used to determine a material’s flash point. US DOT provides a list of authorized flash point test procedures for different liquids in 49 CFR 173.120(c)(i) and (ii).
Professionals use one of two methods to conduct the test—open-cup or closed-cup. Open-cup tests yield flash points a few degrees higher than a closed-cup test. The tests conducted with a closed-cup apparatus produce the more accurate and reproducible results.
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Hazmat Air Shipper Certification (IATA)
Hazmat Vessel Shipper Certification (IMDG)
Find hazmat training for managers and employees with any experience level or job description at Lion.com/Hazmat.
Tags: Class 3, flammable liquids, hazardous materials, hazmat
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