I'm Jake O'Neal, creator of Aniamgraffs. And this is how a fire engine works.
There are many possible model variations for different needs, so I've chosen to focus on
a fairly standard pumper truck designed to transport crew, tools, water, and pumping
capabilities to the scene of an incident. First, let's have a look around the exterior.
Warning lights designed to alert drivers for safe fire truck passage
can be changed to steady beams for proper scene illumination when arriving at a destination.
The pump on this truck is located mid-ship, though front or rear mount pumps are also possible.
Ample rear storage compartments turn this rig into a mobile toolshed. There are folding steps
on the back for roof access, where the hosebed, ladders, and more tools reside.
Coming around to the front, there's an electronic speaker for various warning sounds, a preconnected
hose for quick access when responding to smaller incidents like trash or car fires,
there are loud air horns that can sound as needed by the driver, and a "Federal Q" siren,
which is a mechanical device that produces the classic, familiar "wailing" sound.
Now let's go into more detail, starting with the pump.
Some pumps have manual controls for every task, especially older pump models.
The intake pressure gauge is a compound gauge, meaning it can show values below
atmospheric pressure (or vacuum conditions) when sucking water up from a pool or mobile tank,
or positive pressure when connected to a pressurized source like a fire hydrant.
Since the truck's engine also drives the pump, engine temperature, RPMs, fuel,
and oil pressure are monitored. There's a manual engine throttle knob to control engine speed.
A master pressure gauge shows how much pressure the pump is producing
combined with existing pressure from any incoming water supply.
Various smaller pressure gauges keep track of the many outlets located around the truck,
with their corresponding pull handles and levers to open or close specific outlets.
There are knobs to divert some water for engine and pump cooling, as well as pump primer controls.
The tank filler knob allows incoming water to enter the built-in tank. There's an air
chuck connected to an onboard air compressor. A nearby radio and speaker provides communication
to the pump operator since they may not be able to see the fire scene from this side of the truck.
Supplying sufficient water pressure to any number of outlets
from varying supply sources is a difficult job that requires constant monitoring. So,
pumper trucks may have different levels of automation to aid the pump process.
A digital panel can automatically monitor engine vitals while also altering engine speed to keep
pump pressure constant. Electrically controlled valves can automatically adjust to keep pressure
at desired levels for specific outputs. And some of the newest systems are highly
automated, allowing a crew member to divert attention to other firefighting tasks.
This particular pump is a centrally located, midship design.
It's powered by the diesel engine through the drive shaft.
A metal rotating disc with internal fins called the impeller performs the pumping work.
The pump is rated up to 3,000 gallons (11,356 liters) per minute,
which is about 71 average sized bathtubs full of water every minute.
2 1/2 to 3 in. diameter hoses in a crosslay compartment
allow for quick access from either side, and may be preconnected for fast deployment.
A smaller 1 1/2" booster hose on a reel can be deployed for small fires or used to wash
hazardous substances from a fire scene or firefighting gear after an incident.
The master stream is used when water needs exceed 350 gallons (1591 Liters) per minute, which would
make a handline too difficult to control. A smooth bore nozzle can be attached for range,
or a fog nozzle to create a heat barrier, for example. The master stream is so powerful that
it's generally not safe for use while fire crews are inside a structure.
There are additional inlets and outlets on the other side of the pump,
as well as the front and rear of the apparatus.
An onboard water tank is situated at the back of the truck. It can hold
1,000 gallons (3,785 liters) of water. However, even a smaller handline hose
might deplete the supply in 8-10 minutes. The master stream would empty the tank in 1-3 minutes.
The tank delivers an instant water supply, but crews will be hooking up to a fire hydrant
for anything more than small trash or car fires. The interior of the tank is divided into sections
with baffle walls to tame the sloshing water as the truck travels to and from an incident.
Moving away from the pump and tank, let's examine the rear storage area.
Emergency response vehicles carry tools for the many different incidents they respond to.
This truck has a basic tool selection to give you the general idea.
Starting on the driver's side, there are assorted hose couplings and nozzles.
A concrete saw with gear and tool bags.
The middle compartment has respirator masks, a so-called fireman's axe with the
standard chopping blade on one side and a pointed instrument on the other for digging or prodding,
a fireman's maul which combines a hammer surface with a bladed side and a hook in the handle. A
standard sledgehammer, and a pair of bolt cutters. The last compartment has SCBA (meaning
"self-contained breathing apparatus") oxygen tanks and harnesses.
There are ABC extinguishers. The letters signify what class of fires the extinguisher can be used
on. Class A is for items like trash, wood, or paper. Class B is flammable liquids such as oil,
gas, paint, and so on. Class C is electrical equipment. The powder in these extinguishers
doesn't conduct electricity, making them effective to fight electrical fires.
In the passenger side compartments we have more hose couplings and hoses.
There's lockout and tagout gear for locking and labeling circuit breaker terminals or
main water valves in a building to prevent tampering during or after an incident.
Power tools, extension cords, air hose and pneumatic tools,
various hydraulic spreading and cutting tools sometimes referred to as the "jaws of life".
A purple K extinguisher, which is a dry chemical extinguisher especially suited
for class B or flammable liquid fires. There are various tool cases and familiar
hand tools. A hydrant bag with implements to operate fire hydrants. A high-rise kit for
standpipe valves. Standpipes are pipes linked to the water main inside buildings that function as
a sort of indoor fire hydrant, giving fire crews access to water in large or multi-floor buildings.
The CO2 extinguisher uses carbon dioxide to effectively push available oxygen out of the way,
drowning the fire. These extinguishers are used for electrical fires and sometimes liquid fires.
A high powered gas fan sits nearby, which firefighters place at doors or
openings to remove smoke, heat, or other combustible elements from a building.
On top there's hose beds for storing various hose diameters and lengths.
An average length of hose is 50 ft (15.2 m). A pumper might carry something like 800 feet of 2 ½
inch or larger hose, and 400 feet of 1 ½ to 2 inch hose. For comparison, the standard city
block in the U.S. is 660 ft. on one side. Also on top, there's ladder storage. On the
driver's side there are hard suction hoses for drafting.
Drafting means pulling water from a standing water source like a pool, pond, or portable tank.
When multiple emergency vehicles respond to one incident,
tanker trucks may deliver water to a portable reservoir that other pumper trucks can draft from.
Now let's head to the front of the apparatus, inside the cab.
The driver is tasked with safe driving to and from an incident. The large nearby switchbank
governs many standard items you might find on large trucks of a similar size. There's also a
push button gear shifter. A central panel with a screen monitors truck specific functions but
can also control many additional presets, for example, for different external lighting schemes.
A pull cord sounds the loud horns,
and a foot pedal controls the previously shown Federal Q mechanical siren. The
driver uses the road-to-pump switch to safely engage the pump when the truck is stopped.
The officer rides on the passenger side and handles things like siren control,
external radio communications, the public address speaker,
and command laptop. There's also an officer's side speedometer.
Crew members sit in special fire seats with a bracket and support padding that allows oxygen
canisters to be safely worn while riding to an incident. Brackets overhead stow firefighting
hardhats. There are headsets for communication, handheld radios, and flashlights for crew members.