Is It Time to Change Our Training Yet? Part 4: Magnesium Fires
A small piece of magnesium in the stearing column reacts to water in Delray Beach, Florida. (Photo: Lee Junkins)
Lee Junkins, Midsouth Rescue Technologies
How do we fight these fires?
Many companies make products to extinguish magnesium, but there are many drawbacks to using them:
- Most dept. do not have them on their trucks;
- They are very expensive;
- They are very seldom feasible.
A small magnesium fire can be extinguished by simply flooding it with water from a long distance.
A large magnesium fire would take so much product, that the extinguisher would not supply enough to complete the job and it would simply flare right back up.
Back to basic fire behavior. Magnesium is a class D fire, to put it out you must take away one of the four parts of the tetrahedron:
Oxygen: Many times a small magnesium fire can be smothered by burying it in sand or dirt.
Chemical Reaction: Though some products do work on this phase, it is very hard to stop the chemical reaction, because the main gases magnesium puts off are hydrogen, a very explosive gas, and oxygen, that supports combustion.
Fuel: Obviously we could not take away the fuel in this case.
Heat: This is the main source we must work with, to extinguish magnesium we must cool it below its ignition point.
The most feasible attack on a magnesium fire is:
If it is a small fire:
- Flood it with large amounts of water from a safe distance.
- Never slow the water flow until you know it is completely cool, or it will flare right back and take that much more water to do it again.
If it is a large fire:
- Protect the exposures around it and let it burn it’s self out.
- You will not be able to put enough water on it to extinguish it. and if it is that large the object is already destroyed anyway. Why go to the expense of using chemicals.
Lee Junkins joined the fire service in February 1964 at the age of 18. He is currently a certified NREMT, and certified tech in Rope Rescue, Trench Rescue, Confined Space Rescue, and Auto Extrication. He holds Advanced Firefighter Certification, Level II Instructor, and Certification Coordinator, certificates with the Texas State Fireman’s and Fire Marshals’ Association. He is a member of the National Fire Academy Alumni, with courses such as Challenges for Training Officers, and Public Education Leadership.