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

I can take what I learned in this workshop and apply it to everyday work and relate it to my activities.

Shane Hersh

Materials Handler

I have over 26 years of environmental compliance experience, and it has been some time since I have attended an environmental regulations workshop. I attended this course as preparation for EHS Audits for my six plants, and it was exactly what I was looking for.

Frank Sizemore

Director of Regulatory Affairs

Convenient; I can train when I want, where I want.

Barry Cook

Hazmat Shipping Professional

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

I have been to other training companies, but Lion’s material is much better and easier to understand.

Mark Abell

Regional Manager

Excellent. I learned more in two days with Lion than at a 5-day program I took with another provider.

Francisco Gallardo

HES Technician

The online course was well thought out and organized, with good interaction between the student and the course.

Larry Ybarra

Material Release Agent

The instructor does a great job at presenting material in an approachable way. I have been able to save my company about $30,000 in the last year with what I have learned from Lion!

Curtis Ahonen

EHS&S Manager

The course was very well structured and covered the material in a clear, concise manner.

Ian Martinez

Hazmat Shipping Professional

I like Lion's workshops the best because they really dig into the information you need to have when you leave the workshop.

Tom Bush, Jr.

EHS Manager

Download Our Latest Whitepaper

Spot and correct 4 of the most common universal waste errors before they result in a notice of violation during a Federal or state inspection.

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.