by Chris Woodford. Last updated: November 12, 2013.
Fire gobbles its way through trees and buildings like a hungry
animal—and in a sense that's exactly what it is: a living, breathing animal.
Fire is a chemical reaction that feeds on fuel and oxygen. Give it plenty of both
and it'll keep on burning indefinitely. Thank goodness, then, for firefighters, those brave men and women who set
themselves the job of stopping fire in its tracks. Fire fighting is
one of the toughest jobs there is and it calls for some equally tough
equipment. Let's take a closer look at how to tackle those flames!
Photo: Firefighters wear all-over aluminum suits to tackle the worst blazes; suits made of fireproof Nomex® and Kevlar® are used for less severe fires. Photo by Nathan Lipscomb courtesy of US Navy and Defense Imagery.
Firefighting is a dangerous and demanding job that calls for total teamwork: it can take several people just to hold a powerful fire hose working at full pressure. Men and women make equally good firefighters, but must be no younger than 21 and usually retire at 55. Firefighters have to pass strict medicals and physicals and also take written theory tests. They're constantly trained in new firefighting techniques. Firefighting is a stressful job with long periods of waiting. Often firefighters pass the time at the station by playing games like table football.
Photo: Fire has a voracious appetite for oxygen and, when it burns materials such as plastics, it can give off highly toxic chemicals. That's why firefighters often have to wear breathing apparatus. It's worth remembering that firefighters often have to work in darkness and thick smoke, which makes their job even more difficult and dangerous. Photo by courtesy of US Department of Energy (DOE).
What turns an ordinary man or woman into a firefighter? Apart from
heroic bravery and determination, it's the clothes they wear and the
equipment they use. Firefighters wear jackets made from synthetic
materials such as Nomex® and Kevlar®. They are fireproof,
insulate against heat, and resist many different chemicals. Helmets, made from carbon-based composite
materials, are hard-wearing and shockproof. A special mixture of glass
and plastic protects
visors against high temperatures.
A fire engine has to carry firefighters and equipment to burning buildings. It also has to pump large volumes of water, sometimes over long distances, to extinguish the flames. Typical fire engines carry about 1900 liters (500 gallons) of water and draw bigger supplies from hydrants (like giant faucets positioned on streets—described more fully below) near the scene. They also carry assorted portable extinguishers for tackling smaller or more unusual fires.
Photo: Left: A closeup of the pump inside an airport fire truck. You can connect several different hoses at once and each one has separate controls. There are stopcocks to turn the water on and off and dials to tell you the water pressure. Note the thick, insulated rubber boots the firefighter is wearing to to protect against heat, cold, and resist oils, chemicals, and salt. They also have steel toecaps to protect against impacts. Photo by Rebecca Layman courtesy of US Air Force and Defense Imagery.
Photo: Right: Fire engines as they used to be. This is a horse-drawn fire-engine cart dating from 1880. Note the primitive, bucket-style fire extinguisher pump on the left. It's currently an exhibit at
the National Trust's Lanhydrock country house in Cornwall,
Firefighters don't just put out fires. Most fire departments have dedicated rescue trucks designed for tackling automobile accidents, which carry hydraulic jacks and airbags for lifting overturned vehicles, a punch for breaking windscreens, and high-temperature gas torches that can cut people free from crashed cars. One new tool is a
steering-wheel cover to stop a car's airbag from inflating and injuring firefighters as they work.
Photo: Firefighters from the Washington, DC Fire Department tackle a burning building with hoses and a "hook and ladder" truck (a fire engine equipped with huge onboard ladders and other rescue equipment). One way of using a truck like this is to attach a fire hose to the top of an extended ladder. The hose can then be operated safely by firefighters standing at the bottom, who pull on a cable or swivel the turntable ladder to direct the water. In this case, it's safer because the firefighters don't have to stand so near the flames and heat from the burning roof. Photo by Dave Hyatt courtesy of US Air Force and Defense Imagery.
Ambulances are like miniature hospitals inside, allowing paramedics
to give rapid treatment to casualties at the scene. firefighters tackle
three quarters of all medical emergencies. Fire ambulances carry
equipment to deal with common fire injuries. Respirators help people
breathe normally after inhaling smoke, while defibrillators
are portable electric-shock machines that can often restart someone's heart
if it stops beating properly. Special bandages and
provide treatment for burns. There are also masks, gloves, and
overalls to isolate people contaminated by chemical spills.
A fire hydrant is really nothing more than a large outdoor faucet (or tap, as it's called
in some countries) designed to supply huge amounts of water to fire engines, very quickly,
whenever and wherever fires break out. A typical hydrant has
up to four nozzles, one on each side, to which up to four sturdy fire-hoses can
be tightly screwed. To prevent tampering, the nozzles are held shut
by pentagonal (five-sided) nuts that can be opened only with a
special wrench. At the top, there is a similar nut and sometimes a
wheel directly beneath it. Turning the nut and the wheel unscrews a
valve inside the hydrant. This allows water to flow up from an
underground pipe and out through whichever nozzles have been opened.
Unlike an ordinary faucet, a fire hydrant is designed to operate either
completely on or completely off.
Photo: Fire hydrants are like faucets that stop up water supplies
under high pressure. That's why the water really sprays out when they're opened.
Photo by Stephen Schester courtesy of US Air Force and Defense Imagery.
It can take an enormous amount of water, sprayed for several hours, to
put out a large urban fire—and time is always of the essence for
firefighters. Ordinary faucets could not possibly supply enough water
to do this job quickly enough: they are designed to supply small
amounts of water over short distances and at quite low pressures. In
this respect, fire hydrants are very different. Where a domestic faucet
can provide just enough water to power a garden hose around 2 cm
(0.75 inch) thick, a fire hydrant can fill a hose up to eight times
thicker. Even the most powerful domestic faucet can deliver only a few
gallons of water every minute. But a typical fire hydrant can supply
water up to a thousand times faster. The water from a fire hydrant is
at several times higher pressure than the water in your faucets at home:
it can come out of the hydrant at 80 psi or more (roughly six times
the pressure of the air we breathe).
Fire hydrants are the most visible part of our emergency water systems—but
they are not the only part. The water that supplies hydrants comes
from large tanks or reservoirs usually located on hilltops. Each of
these is designed to supply enough water to operate fire hydrants for
hours at a time. The tanks are connected to the hydrants by a system
of pipes laid out in a grid pattern. This means the water can travel
from any tank to any hydrant via several different routes, so a
hydrant will continue to work even if one of the pipes springs a
When a firefighter opens the valve on a hydrant, the force of
gravity makes water run downhill from the tank, through the grid of
pipes, to whichever hydrant nozzles are open. The higher the tank is
located, the more speed and pressure the water will build up, the
quicker it will be delivered—and the faster the fire will be put
Parts of a fire hydrant
Fire hydrants are just fire hydrants, right? Wrong! Here are some of the little details
you might not have noticed:
- Operating nut on top of hydrant turns main water valve on or off
- Hose is attached to one of the four sides of the hydrant. A clapper valve just inside the hydrant stops water from flowing backwards. Water can flow out of the hydrant into the hose but not in the opposite
- Raised metal body of hydrant ensures it operates at the same height as a fire engine's water inlet.
This helps to stop fire hoses from kinking.
- Breakable bolts on base are designed to snap if a vehicle strikes the hydrant.
- Safety chain stops nozzle caps from getting lost when hydrant is in
- Outlet nozzles have screw threads inside to which fire hoses can be securely attached. Remember that the
water is at very high pressure and the hoses will come off if they're not screwed on tight!
Photo: Key parts of a fire hydrant. Photo by Perry Aston taken at Joint Base Andrews, Md, and published courtesy of US Air Force and Defense Imagery.