WPI Research Underpins New Federal Law on Gas Can Safety

It happens only under limited conditions, but when it does, the results can be horrific. When a portable plastic gasoline container is nearly empty and is tilted to pour out the last few ounces, a zone of highly flammable vapors can form in the top of the can and in the spout. A nearby ignition source can cause a cascade of flames to race down the spout, producing an explosion.

A report by NBC News correspondent Lisa Myers and producer Richard Gardella, broadcast on the Today show in December 2013, documented a number of cases nationwide where such explosions caused severe burns; the report noted that according to Consumer Product Safety Commission (CPSC) data, gas can explosions had led to at least 11 deaths and 1,200 emergency room visits since 1998. That report also documented research conducted in WPI’s Combustion Laboratory, including dramatic video of commonly sold red containers exploding on a test stand.

Motivated by reports of portable gas can explosions that dated back to the 1970s, the WPI research, conducted by PhD candidate Brian Elias and Ali Rangwala, professor of fire protection engineering, and supported by ASTM International, an organization that establishes standards for consumer products, including gas cans, sought to establish the conditions under which explosions can occur. Their conclusions, published in Fire Science Journal in May 2013: the greatest explosive risk is present when the cans contain 30 milliliters or less of gasoline (equivalent to about 2 tablespoons), when the air is cool, and when the can is tilted at a common pouring angle of 42 degree.

“I am very proud and happy to see that the work we did on flame arresters for gas cans has led to the passing of a law by the U.S. Congress.”

In two subsequent phases of the ASTM International-funded study, Elias and Rangwala explored possible mitigation measures. In particular, they looked at the effects of flame arrestors, devices with metal or plastic mesh that can keep flames from propagating into a container. The devices are already found in metal “safety” gas cans, fuel tanks, and some containers of other flammable liquids.

In a 2016 report, Rangwala and Elias found that flame arrestors can, indeed, prevent explosions in plastic gas cans. In fact, they concluded that these mitigation devices are “necessary.” They noted that some prototype gas cans containing flame arrestors had passed safety tests. The WPI research reinforced a recommendation from the CPSC, which, the day after the NBC story ran, called on manufacturers to add flame arrestors to plastic gas cans.

Read an NBC News report on the Portable Fuel Container Safety Act and watch a video of a gas container explosion demo conducted in WPI’s Combustion Laboratory.

Thanks to the Portable Fuel Container Safety Act of 2020, a new law included in a massive appropriations bill passed by Congress late in 2020, that recommendation and the conclusions of Elias and Rangwala are now backed up by federal law. The act, sponsored by Rep.Henry Cuellar of Texas, requires that the millions of plastic gas cans sold in the United States each year include flame mitigation devices. Specifically, it establishes “performance standards to protect against portable fuel container explosions near open flames or other ignition sources” and directs CPSC to “promulgate a final rule to require flame mitigation devices in portable fuel containers” within the next two and a half years.

Asked for his reaction to the law by NBC News, Rangwala said, “I am very proud and happy to see that the work we did on flame arresters for gas cans has led to the passing of a law by the U.S. Congress.”

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