Recently, one of Semco’s neighbor companies had a magnesium fire on their property. Magnesium fires are no trivial matter; extinguishing them is notoriously risky and difficult. Little known to most people, but well known to firefighters and industries that work with magnesium, is that a magnesium fire is a problem with a graphite solution. In fact, the most disposable graphite material—graphite dust—is one of the most effective substances used to smother and eventually extinguish a magnesium fire. Understanding why the firefighters requested Semco’s help with this particular fire requires a little science, and maybe a visit to YouTube.
If you spend much time watching home science experiments on youtube, chances are you’ve come across a video of someone tossing a chunk of sodium into a pail of water. The sodium quickly explodes into fire after hitting the water. Similar videos exist for other alkaline metals like lithium and potassium. Our fascination with these reactions is rooted in how counterintuitive they are; imagine water causing, rather than putting out, a fire. One alkaline metal you don’t have to worry about catching fire in the presence of water is magnesium. This substance notoriously burns hot and bright, so bright you should probably wear sunglasses to look at it. Magnesium is popular with backpackers who carry small blocks of the substance with a flint as an emergency fire starter. Even if it’s raining, you can shave a little magnesium off the block with the flint, strike a spark, and get your fire going. However, if magnesium is already burning when it comes into contact with water, an explosion will occur. With a small amount of burning magnesium, and a little water, the reaction is not dangerous, hence why backpackers use magnesium to start fires in wet conditions. However, if a large stockpile of magnesium were to catch fire, one of the worst things to do is to spray water on it. Doing so can precipitate a fireball, showers of sparks, and a plume of toxic smoke. Do not use water on a magnesium fire! Large quantities of graphite dust is much better even than dry sand.
The knowledgeable firefighters of Lorain, Ohio knew this well. When they were called to a large magnesium fire at our neighbor company, they requested from us as much graphite dust as we could spare. Fire extinguishing is not one of your typical graphite applications, but graphite, because it does not burn and tolerates extremely high temperatures, is effective at smothering magnesium fires. Once the fire was localized and our graphite dust was poured over it, the fire was contained and on its way to being snuffed out entirely. Not a class d fire extinguisher, of course, but a fire extinguisher, nonetheless!
This magnesium fire fighting job was a victory for neighborly cooperation, for the Lorain Fire Department, and for that most humble graphite material, dust. Semco does not manufacture graphite dust to be used as a fire retardant, but it works. If you or your company works with magnesium, it’s a good idea to have some dry fire retardant around, in case of a magnesium burn, and few substances work better than graphite dust. At Semco, we’re proud to be the home of even the most obscure and unlikely graphite solutions.