Introduction: Dorky Firefighter Fire Extinguisher

About: Firefighter/EMT, avid tinkerer, always loved working with my hands. Interested in a lot of things, so my tinkering tends to make dorky appearances.

I'm a new volunteer at the local fire house and I learned an interesting way to put out a fire. With summer rolling in at full force, so do rates of easily preventable fires taking charge. In this 'ible, you'll learn how to have an affordably fire-safe summer.

Background/General Knowledge

There are five classes of fire that are controlled by different types of fire extinguishers. For now, what matters are Class A, B, and C fire extinguishers, which control combustible dry materials (such as paper, wood, and cloth), flammable liquids (such as gasoline, oil, and paint), and electrical fires respectively. The ingredient in common? Sodium bicarbonate, commonly known as baking soda.

Chemistry Saves Lives

The chemical reaction stands to reason:

When heated above 50 C, sodium bicarbonate is decomposed to sodium carbonate, water, and CO2.

2 NaHCO3 ā†’ Na2CO3 + H2O + CO2

At 850 C, the carbonate is converted to an oxide.

Na2CO3 ā†’ Na2O + CO2

The long and the short of it, the heat from the fire is used to drive the reaction that yields CO2, thereby replacing oxygen, which supports combustion.


The original idea trademarked at this fire company by a seasoned veteran was that a plastic bag full of baking soda could be dropped down a chimney to put out a fire, known as a "chimney bomb". Fire melts the bag, baking soda gets released, fire is extinguished.

In reality, this bagged baking soda method is in no way ideal. If by chance you are caught in a situation where there is a fire and have a box of baking soda but not a certified fire extinguisher, it would be helpful. Helpful, but again, in no way ideal.

The main purpose of this Instructable is to give a quick and simple chemistry lesson. The safest way to proceed with this chemistry experiment is to attempt extinguishing a candle flame.


While this DIY fire extinguisher is as workable as a Class A, B, and C fire extinguisher, it should not replace a certified fire extinguisher. Above all, this should supplement your fire extinguisher in the event of a fire.

In the event of a fire, call 911.

Do not test the effectiveness of this Instructable at home.

Step 1: Materials

All you need for this DIY fire extinguisher is:

-A plastic bag (preferably not ziploc)

-A box of baking soda

-Optional cutting board to contain the mess

Step 2: Filling

Simply fill your bag with baking soda. I'd recommend using the whole box. You never know, you might need the whole thing. For bags this thin with such a capacity, I wouldn't recommend using more than a box. The bag could break open unexpectedly and leave you with a mess and without fire protection.

Step 3: Tie Off

An overhand knot will do. If you see yourself wanting to add or remove baking soda in the future, you might want to go with a figure-eight knot.

Step 4: Ready for Use

To take my own advice from the introduction, I won't document proper technique. Just know that this DIY fire extinguisher is usable for Class A, B, and C fires. In other words, dry combustible materials, electrical fires, and flammable liquids.

In the event of a fire, toss the bag into the fire source. Do not open the bag and sprinkle its contents on the fire. The point of the bag is a last resort to keep you safe. Getting close to the fire puts you in danger. Using the DIY fire extinguisher should buy you enough time to call 911 for assistance before the fire gets out of control.

This DIY fire extinguisher should not replace a certified fire extinguisher, only supplement.

This DIY fire extinguisher will not put out a large fire. If large fire danger is high, use a certified fire extinguisher.

In the event of a fire, call 911.

Do not test the effectiveness of this Instructable at home.


Kitchen fires are best extinguished with wet chemical extinguishers, so a Class K fire extinguisher would be a good investment unless you have an electric stove. Same applies to flammable metals, which are controlled using Class D fire extinguishers.