How Fire Extinguishers Work? Video Lecture | Science Class 8

hey everybody if you're like me then you
constantly worry about buildings
catching on fire when someone plays your
newest mixtape and since you can't
compromise your artistic integrity
because of a few exploding sound systems
you have to be prepared for the blazes
that inevitably ensue
once the beat drops a fire extinguisher
is one of your best option but what are
these things anyway
how do they work great question the
subject of this episode first let's talk
about fire fire is the result of a
chemical combustion reaction typically
between oxygen and some sort of fuel
like wood or gasoline for the reaction
to occur the fuel has to reach its
ignition temperature for wood that's
about five hundred degrees Fahrenheit or
260 degrees Celsius the heat decomposes
some of the woods cellulose and that
decompose stuff is released as volatile
gases like a compound of hydrogen carbon
and oxygen when the gas is hot enough
its molecules break apart the atoms
recombine with the oxygen to form water
carbon dioxide and other products this
heat keeps the fuel at the ignition
temperature so it keeps burning as long
as there is fuel and oxygen there you
have it fire the result of extreme heat
oxygen and fuel fire extinguishers
remove at least one of those elements
from the equation imagine a fire
extinguisher cut in half so that plastic
siphon tube there leads from the bottom
of the fire suppressant reservoir to the
top of the extinguisher a spring-mounted
valve blocks the passageway from the
siphon to the nozzle at the top of the
cylinder there's a smaller cylinder
filled with a compressed gas liquid
carbon dioxide for example a release
valve keeps the compressed gas from
escaping when you pull out the safety
pin and depress the operating lever it
pushes on an actuated rock the rod
presses the spring-mounted valve down to
open up the passage to the nozzle the
bottom of this actuated rod has a sharp
point which pierces the gas cylinder
release valve the compressed gas escapes
applying downward pressure on the fire
suppressant material and this drives
that fire
stop up the siphon out the nozzle the
proper way to use the extinguisher is to
aim it directly at the fuel not at the
flames and spray in sweeping motion
there are three main types of
extinguisher a water extinguisher can
put out things like burning wood or
paper or cardboard but it's no great
shakes at electrical fires or fires
involving in flammable liquids in an
electrical fire water might actually
conduct the current which could
electrocute you
then there's the carbon dioxide
extinguisher the co2 is kept in a
pressurized liquid form when the
container is open the co2 forms a gas
this gas is heavier than oxygen so it
displaces the oxygen surrounding the
fuel this type of extinguisher is the
one you'll find most often restaurants
because it won't contaminate cooking
equipment or food
however ladies and gentlemen drumroll
please the most popular fire
extinguishing material that's the dry
chemical extinguisher these cylinders
contain foam or powder typically made of
sodium bicarbonate you may know it by
its street name baking soda baking soda
starts to decompose at only about 158
degrees Fahrenheit which for everybody
but the u.s. is 70 degrees Celsius and
when this stuff decomposes it releases
co2 the co2 along with the installation
of the foam smothers fire however be
careful most fire extinguishers contain
a small amount of suppressant you can
use it up in seconds and that's why
they're only effective on relatively
small fires to put out a bigger blaze
you need more equipment like a fire
engine as well as hopefully some trained
professionals but for the conflagration
that can pop up in your house a fire
extinguisher is a lifesaver that's it I
mean remember again if you have to use
one hit the fuel not the flame and sweep
across the fire thank you so much for
watching
toss me a like if you dug this video let
me know which other gadgets I should
cover in the future and stay tuned next
week for more brain stuff