How Long Does a Flash Fire Last?

By definition, a flash fire is a brief thermal hazard that occurs when a flame front moves rapidly through a diffuse fuel cloud, eating up the fuel as it goes.

Although recent editions of the standards use the term “brief” rather than attaching a specific duration to the definition, independent university research has repeatedly shown that flash fires are in fact limited to a maximum duration. How long? Scott Margolin, Vice President of Technical and recognized subject matter expert, explains:

This is good news for workers. Because flash fires are very brief, typically 3 seconds or less, we can protect people from fatal or catastrophic injury with single layer, secondary protective apparel – that is, by wearing FRC. FRC will not ignite and continue to burn when the flash fire is over, and insulates you from the hazard, dramatically reducing or eliminating burn injury.

When evaluating FRC options, it’s important to ask for the body burn data, rather than just a checkmark that the item passes. Some manufacturers will provide data for greater or lesser durations than 3 seconds. While more data is generally a good thing, there are a few important steps to take to make sure you’re seeing the full gamut of possible outcomes from inception of burn through the fabric to failure to ensure manufacturers aren’t cherry-picking data that paints their product in a favorable light. Scott Margolin explains in this video.

Want to learn more about flash fire and protecting workers? Browse the flash fire section of our online FR Safety Library, and don’t miss these other posts:

Have a technical question we haven’t answered yet? Send an email to and the answer to your question could be featured in an upcoming video and/or blog post! You can also use the bar on the right to request a complimentary technical consultation with Scott Margolin.

Leave a Reply

Your email address will not be published. Required fields are marked *