Search

What is Flash Point for Flammable Liquids?

Posted on 10/12/2021 by Roseanne Bottone and Roger Marks

Flash point is the lowest temperature at which a combustible substance gives off enough vapor to form an explosive or ignitable mixture with air. In plain English, it is the temperature at which a material’s vapors will ignite and keep burning.

The lower a material’s flash point is, the greater the risk of a fire involving the material. People who ship and transport hazardous materials use flash point to measure the risk of an explosive or ignitable mixture forming when a liquid escapes from its container or packaging.

Here are examples of two liquids, one with a "low" flash point and one with a "high" flash point.

Low Flash Point

100% isopropyl alcohol (isopropanol)

Flash point: 11.7°C (53°F)
Even when kept cool, isopropanol can ignite and burn steadily

High Flash Point

Mineral oil

Flash point: Around 225°C (440°F)
Unless heated dramatically, mineral oil does not pose a fire hazard.

Under the United States Department of Transportation’s Hazardous Materials Regulations (HMR), a liquid with a flash point at or below 60 degrees Celsius (140°F) is a Class 3 flammable liquid. A liquid with a flash point above 60 degrees Celsius (140°F) but below 93°C (200°F) is a combustible liquid.

Flammable and combustible liquids are subject to requirements for classification, naming, packaging, marks and labels, placarding, reporting, shipping records, training, and more.

Employees involved in shipping or transporting flammable and combustible liquids must complete DOT hazmat training to safely do their jobs and ensure compliance with US DOT (and international) regulations. US DOT’s Hazardous Materials Regulations are found in Title 49 of the Code of Federal Regulations (49 CFR), Parts 100 to 181, et al.

How to Test Flash Point

A flash point test works like this: A specified quantity of the liquid at a low temperature is placed in a receptacle. The material is heated slowly. Periodically, a small flame is brought near the surface of the liquid. The flash point is the lowest temperature at which a “flash” is observed.

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.

Packing Groups for Class 3 Flammable Liquids

Together with the material’s boiling point, flash point is also used to determine the degree of hazard posed by a flammable liquid, also known as the material’s Packing Group (PG) in hazmat-speak. The PG dictates the strength of package required to contain the material.

Like many DOT hazard classes, Class 3 (Flammable liquids) is divided into three Packing Groups—I, II, and III.

Among all flammable liquids, PG I materials pose the greatest danger in transportation. PG III materials pose the lowest degree of danger. Combustible liquids are assigned to Packing Group III.

A liquid's flash point is a crucial piece of information that influences how flammable liquids are classified, packaged, and transported safely. Class 3 flammable and combustible liquids are among the most frequently shipped types of hazardous materials every year, according to the US Census Commodity Flow Survey.

Online Training to Simplify Hazmat Shipping Compliance

Develop a step-by-step approach to ship hazardous materials in full compliance with current US and international regulations! The Hazmat Ground Shipper Certification (DOT) online course prepares new or experienced shippers to properly classify, name, package, mark, label, handle, and document hazardous materials shipments for highway transportation.

The course is designed to help satisfy US DOT PHMSA's hazmat training mandate for hazmat employees at 49 CFR 172.704. US DOT requires training every 3 years for hazmat employees. 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.

Tags: DOT Class 3, flammable liquids, flash point, hazmat classification,, shipping hazardous materials

Find a Post

Compliance Archives

Lion - Quotes

My experience with Lion training, both online and in the classroom, is that they are far better organized and provide a better sequential explanation of the material.

Robert Roose

Manager, Dangerous Goods Transportation

Best course instructor I've ever had. Funny, relatable, engaging; made it interesting and challenged us as the professionals we are.

Amanda Schwartz

Environmental Coordinator

Lion does a great job summarizing and communicating complicated EH&S-related regulations.

Michele Irmen

Sr. Environmental Engineer

I used the IT support number available and my issue was resolved within a few minutes. I don't see anything that could have made it better.

Danny Province

EHS Professional

Very well structured, comprehensive, and comparable to live training seminars I've participated in previously. I will recommend the online course to other colleagues with training requirement needs.

Neil Luciano

EHS Manager

The instructor was excellent. They knew all of the material without having to read from a notepad or computer.

Gary Hartzell

Warehouse Supervisor

This is the best RCRA training I've experienced! I will be visiting Lion training again.

Cynthia L. Logsdon

Principal Environmental Engineer

The instructor was very patient and engaging - willing to answer and help explain subject matter.

Misty Filipp

Material Control Superintendent

Lion courses are the standard to which all other workshops should strive for!

Brody Saleen

Registered Environmental Health Specialist

Best instructor ever! I was going to take my DOT training w/a different provider, but based on this presentation, I will also be doing my DOT training w/Lion!

Donna Moot

Hazardous Waste Professional

Download Our Latest Whitepaper

Some limited quantity reliefs are reserved for specific modes of transport. Use this guide to identify which reliefs you can capitalize on, and which do not apply to your operations.

Latest Whitepaper

By submitting your phone number, you agree to receive recurring marketing and training text messages. Consent to receive text messages is not required for any purchases. Text STOP at any time to cancel. Message and data rates may apply. View our Terms & Conditions and Privacy Policy.