What is a Flame Arrester?

A flame arrester is a small screen often installed in charcoal lighter fluid bottles, water heaters and high-proof, flammable alcohol products to stop fuel combustion by extinguishing a flame or preventing it from expanding into a container. Flame arresters are mandatory in gas cans used on industry work sites, and certain gas can officials have acknowledged that they are not allowed to use their own defective cans on their manufacturing plant sites.

Flame arresters
Flame arresters shown in a safe metal gas can, outside of the metal gas can housing, and a smaller flame arrester used in a red plastic gas can.

If a gas can has no flame arrester, it is at high risk of exploding. Here’s how a flame arrester works:

A flame arrester is a small device that acts simply as a screen to filter out a flame or a spark. Air and liquid should be able to pass through your can’s spout, but the size of that hole can determine whether or not a flame or a spark can pass through it as well, much like the screen in front of a fireplace. Thus, when gasoline vapors are ignited outside of your can and flash back to the source of the fuel like a fuse to a bomb, the arresting screen prevents the flame or spark from entering the can, causing it to explode.

This safety device is critical given that the risk of explosion is actually created by the vapors contained inside the gas can itself as opposed to the gasoline within it. Under the right conditions, even a few milliliters of gasoline can cause a violent explosion when gasoline is improperly contained in a can lacking a flame arrestor. Gas cans of this nature have exploded when consumers were performing tasks as basic as filling up their lawnmower, chain saw or simply walking with the can.