Randoms Flashcards
Roles of a firefighter
Take action to save / preserve life
Take action to save / preserve property
Render humanitarian services
Protect the environment
What methods can be used to extinguish a fire
cooling
exclude oxygen
remove fuel
flame inhibitors / extinguishers
What is ventilation
is what can cause a fire to a flashover
by removing heated air, smoke or other airborne contaminants from a room or building and replacing with fresh clean air
we can use a few methods to do this open a window / door automatic vents natural ventilation like wind or use of a tactical fan
What are the positive effects of ventilation
PPV can assist in the venting of smoke and high temperature combustion products and make attacking the fire easier
Limits of flammability
lower explosive limit
upper explosive limit
ideal mixture
What are the three types of spreed
conduction
convection
radiation
What is a flashover
is the stage where the total thermal radiation from he fire plume, hot gases and compartment boundaries causes all exposed combustible surfaces to pyrolyse with the release of flammable gases and they will ignite when there is adequate ventilation
so all of a sudden it can go from a sustained position and transition to a growing fire and further to a fully developed fire
Signs of a flash over
supply of fresh air / ventilated fire lowering neutral plane remote surfaces pyrolysing flames visible rapid increase of temperature
what is a backdraft
with limited ventilation this can lead to a fire in a compartment, producing fire gases and containing sufficient proportions of partial combustion products having unburnt pyrolysis products, if these accumulate and with the admission of air when an opening
is made to the compartment, this is where it can lead to a sudden deflagration, this deflagration will move through the compartment and out the opening due to being drawn that way.
signs of a backdraft
low neutral plane blackened windows hot doors and windows pulsating smoke whistling sound in rush of air when an opening is made ghosting tongues of flames seen in the compartment under ventilated
When are wet and dry risers used
some maybe most buildings have a wet riser or wet standpipe system where the pipes are kept full of water for manual or automatic fire fighting operations
dry risers are used when water pressure of a building wouldn’t be enough for fire suppression and in unheated buildings where the pipes could freeze
used for buildings over 20m in height wet or dry risers can be used but dry risers are recommended
for buildings over 60m in height wet risers must be used
what branch techniques do we use to put out a fire
when a fire is ignited, the way to put it out depends on the fuel that is making th fire burn and then the location of the fire
fog attack - ideal for closed compartments where no wind
indirect attack - aimed at the ceiling, the water drops down and extinguishes the fire from above
direct attack _ suffocating the flames as the water is aimed at the base of the fire
combination attacks _ using bothe direct and indirect techniques to combat the overhead gases and flames simultaneously
What is the purpose of the spinning teeth on a hose reel
to provide a very wide protective fog pattern, with the water being directed to the outer portion of the pattern to gain a wide angle
What is a pump
centrifugal pump are the most common type of fir truck pump. water enters the pump through the inlet, then goes into the centre of an impeller spinning on a shaft. the water spins outwardly through the impeller vanes into a volute casing, which increases the pressure
advantages of a positive displacement pump
can move fluids that are not only higher in viscosity but also those that range from liquefied gases to water like fluids, sliding vane and medium to very-viscous fluids eccentric disc and sliding vane.
successful in chemical plants
less cost
can give a constant flow at a given speed
great for chemical-manufacture applications because they require precise dosage rates
wide array of transfer applications, fluid and chemical
