IN SHORT: While some substances dropped on a fire can smother the flames, flour should not be used for this purpose. Flour can fuel a fire.
A video that has been shared widely on social media shows a man dressed in protective overalls walking up to a small tank of gas that is spewing flames. He casually drops a handful of white powder on the tank's gas valve, and the flames go out.
The video has been shared many times with claims that the white powder is flour, of the kind used for baking, and that a handful of flour can "prevent a gas disaster" or similar messages.
The video was also shared with Africa Check via WhatsApp.
But this claim is dangerous. Flour can actually intensify a fire, and should not be used to douse flames.
Flour will burn and can cause deadly explosions in worst-case scenarios
Tanks filled with gases such as liquid petroleum gas or propane are used widely in the house for cooking and heating. But they often attract false safety claims.
The video, originally shared on TikTok, features a caption in Arabic which says it demonstrates how "flour and powder" can be used to extinguish a blazing gas cylinder. Machine translation of the caption translates the phrase as "powder and flour".
But flour is not a safe method for extinguishing fires, because flour is highly flammable, as demonstrated here by the UK's Royal Society of Chemistry.
When suspended in clouds in the air, flour can even cause large and deadly explosions, though this is a danger mostly in industrial flour mills and is not likely to happen in ordinary kitchens.
But there are other substances which can be used to safely extinguish fires.
Other flour-like substances can safely douse flames
Bicarbonate of soda, also called baking soda or sodium bicarbonate, can be used to douse flames, as can ordinary cooking salt (or sodium chloride). Neither of these is flammable like flour. But they aren't necessarily efficient methods of putting out a fire.
(Note: Baking powder is flammable, and is sometimes confused with bicarbonate of soda.)
Cooking website Bon Appétit writes that "you'll need a lot" of bicarbonate of soda to extinguish a fire. Another home-cooking site, The Kitchn, also writes that it "takes a lot of baking soda" to extinguish a grease fire. Both sites instead suggest turning off the heat and covering a burning pot tightly with a lid. If these steps don't get a fire under control, they recommend owning a fire extinguisher, in case of emergency.
If the fire has been caused by a gas tank, manufacturers recommend taking the following actions:
Removing tanks from the fire or the source of the fire.
Shutting off the gas valve on the tank.
Using a dry powder or carbon dioxide fire extinguisher to extinguish the flame.
Slapping or covering the flame with "a glove, heavy cloth or a garment soaked in water" to extinguish the flame.
Calling fire or emergency services to deal with the fire.
Keeping the tank or nearby tanks cool by spraying them with water from a hose at a distance (not trying to extinguish the flames with the hose). Do this after contacting help.
Understanding how fires burn can be a useful guide to understanding how to put them out.
A general guide to putting out a fire
In general, fire requires three things to burn. These are oxygen, fuel and heat, a combination referred to as the fire triangle. Removing one of these three elements will extinguish a fire.
Water is often used to douse fires because it effectively absorbs heat, but it cannot be used in all cases. It should not be used to put out electrical fires, as water conducts electricity. Water can also worsen grease fires, such as a burning pan of oil.
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These kinds of fires should be extinguished by removing their source of oxygen. When a fire extinguisher is not available, firefighters recommend placing a pot lid firmly over a pot to cut off oxygen to a grease fire in a kitchen.
A fire blanket, a blanket of flame-resistant material specially made for this purpose, can also be used to cut off oxygen to a fire. An ordinary blanket doused in water can also be used in a similar way to put out a burning gas tank.
This is also how baking soda or salt can be used to extinguish a fire. They smother the fire, robbing it of oxygen. Flour, on the other hand, can be fuel for a fire. Fuels can smother a fire, as anyone who has put too much wood on a campfire can confirm. But it is not safe to try and put out a fire by adding more flammable material to it.
Fire extinguishers work differently depending on the type of extinguisher, although they typically use a combination of cool material and some method of cutting off oxygen to a flame to extinguish it. To be safe, have one of these on hand when you're cooking.
