Fire blankets
by Chris Woodford. Last updated: May 18, 2011.
We all make mistakes—but some mistakes
are serious enough to put
your life at risk or even kill you. If you're foolish enough to leave
your stove unattended, you can cause a serious, life-threatening
fire. But you can make matters far worse by tackling a fire like that
the wrong way. One thing you must never do is put water on a hot
oil ("chip-pan") fire, because that can produce a massive fireball. A
good way to tackle chip pan fires is to use a simple fire blanket.
What are fire blankets and how do they work? Let's take a closer look!
Photo: A basic fire blanket removed from its
protective plastic case and ready to use. Note the black tapes at the bottom that
you pull on to release it. Get one of these and hang it up in your kitchen, away
from the stove, where it's ready if you need it.
Break the triangle
Understand the science behind a fire and you're halfway to putting it out.
Fire is a chemical reaction between oxygen (from the air) and fuel (something that will burn to release energy),
but it doesn't happen all by itself: you need to add some energy (in the form of heat) to kick it off.
Another way of looking at it is to say that most everyday fires need three things to be present: heat, oxygen, and fuel. As long as there's plenty of all three, a fire can go on burning indefinitely. But take away one of them
and the fire will go out. This idea is called breaking
the fire triangle and it's the basic theory of fighting most
fires. You can put out a fire by cooling it down (removing the heat),
cutting off the air supply, or getting rid of the fuel (the usual way
to do this is to remove combustible materials from near a fire and
stopping it from spreading with things like fire breaks).
Photo: Breaking the fire triangle: removing one
or more of heat,
air (oxygen), or fuel is the way to tackle most everyday fires.
If a fire breaks out in your home, generally the best thing to do
is get out as quickly as possible without panicking, close the doors
behind you, and call the fire brigade. But it may be safe for you to
tackle a small fire yourself, in the early stages, with a fire extinguisher or a fire blanket.
If you have a hot oil (chip pan) fire
in your kitchen, the most effective way to tackle it is to place a
fire blanket on top of it to cut off the oxygen supply. If you have no
fire blanket, soak a tea towel in water, wring it out, then place that
completely over the pan. Both of these methods break the fire triangle by removing air.
How to use a fire blanket
If you're not sure how to use a fire blanket, be sure to read the
instructions on the container when you buy one so you know how to do
it properly should the need ever arise. The basic idea is:
- Turn off the heat if it's safe to do so.
- Don't move the pan.
- Go to the fire blanket. Pull on the tapes to release the blanket from its container.
- Wrap the blanket around your hands before you go near the fire so you don't burn yourself in the process.
- Put the blanket over the container to smother the flames.
- Leave the pan to cool completely.
- Now leave the fire alone, get out, and if necessary call the fire brigade. Do not go back to the fire and do not uncover it again
until it is completely cool.
If you have any doubt about whether you can tackle a fire safely without risk to yourself or others, just leave it alone, alert any
other people nearby, get yourselves well away, and call the fire service immediately.
How not to tackle a chip-pan fire
Never throw water onto a hot oil (chip-pan) fire. What happens is
that the water will boil and turn to steam extremely quickly,
throwing a huge spray of burning oil droplets high into the air.
Because the oil is burning, spreading it out like this gives it rapid
access to much more oxygen—and this is what causes a fireball. If
you want to see how deadly this can be, watch this
public service fire safety video
on YouTube made by the British Fire Brigade. It shows you how to tackle a kitchen fire safely and calmly.
Never use a fire extinguisher on a chip-pan fire, for the same
reason. A water extinguisher will have the same effect as throwing on
water, a carbon dioxide extinguisher will blast and spread the hot
burning oil, and a powder extinguisher can cause an explosion. That's
why a fire blanket is generally the best thing to use.
And remember: if in doubt, just get out! Leave the fire and get yourself to safety.
More about fire blankets
Fire blankets are made from thick wool treated with a flameproof
coating, fiberglass, or flameproof synthetic materials such as Nomex®
and Kevlar®. They're not just for
chip-pan fires: you can use
them to help tackle chemical fires wherever it's safe to do so. You
can also wrap them around someone whose clothes have caught fire, or
you can wrap them around your body to help you escape from flames.
Photo: You can clearly see the woven fiberglass
in this blanket. It looks and feels a bit like a sturdy, flameproof tablecloth.
Why doesn't a fire blanket burn?
The secret of a fire blanket's success is that you can throw it over burning oil—or burning
anything—without risk of it catching light. How come? Why do some things burn
and not others?
?
Fire, as we saw up above, is a chemical reaction between a fuel and oxygen that's kick-started
by heat energy. Not everything burns when you apply heat. Apply heat to a block of ice and it doesn't
burst into flames: instead of a taking part in a chemical reaction, it undergoes a physical transformation:
it changes from its solid state (ice) to a liquid (water) or gas (steam).
Fireproof materials (such as those used in fire blankets) are chosen for the job because
they don't burn at the kinds of temperatures we see in everyday fires; apply
heat and they do eventually change form—but in other, safer ways. Take Nomex®, for example. It's a nylon-like plastic, based on carbon, that simply doesn't burn. Apply enough heat to it and you'll char it—reduce it mostly to carbon—but
it doesn't actually burn in the same way as other carbon-rich materials (such as wood) and it doesn't melt or drip.
Further reading
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