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Fire Apparatus Driver/Operator - Pumper Module 4
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FIRE APPARATUS DRIVER/OPERATOR -PUMPER MODULE 4 COMPLETE
DETAILED CASE STUDY
l One gallon of water weighs? - 8.33 lbs
Water freeze and boil temperatures? - Freezes: 32° F
Boils: 212° F
Water expansion ratio at 500° F. - 1,700 to 1
Law of Specific Heat - Ability of any substance to absorb heat. Water is the standard for measuring
specific heat and is given a value of 1.0
Specific heat is measured in British Thermal Unites (BTUs).
Latent Heat of Vaporization - The amount of heat needed to turn a liquid into a vapor.
It takes one BTU to raise one pound of water 1°, up to 212° F. Once water reaches 212° F, each pound
requires an additional 970 BTUs to convert it to steam.
Knowledge Check 1
1. Most extinguishing agents require less than one BTU to raise their temperature 1° F.
2. This is the heat absorbing capacity of a substance.
3. Water absorbs over 950 additional BTUs going from 212° F to steam.
,4. This is the amount of heat needed to turn a liquid into a vapor. - Law of specific Heat
1&2
Law of Latent Heat of Vaporization
3&4
Heat Absorption - Speed at which water absorbs heat depends upon the amount of water surface
exposed to the heat.
Example
Fog nozzle flowing at 100 gpm for a room 96x50x10 will fill a room with steam using the different
patterns. - Straight Stream: 9 Minutes
Narrow Fog: 6 Minutes
Wide Fog: 1.5 Minutes
Advantages of water as an extinguishing agent - Can absorb large amount of heat before turning to
steam
As surface area increases, heat absorption speeds up
Steam occupies 1,700 times its original volume as water
Water is plentiful in most areas.
Disadvantages of water as an extinguish agent - High surface tension limits its penetration into dense
materials
,Incompatible with or reactive to certain fuels and combustible metals
Ice makes roofs and ladders slippery an can make equipment malfunction
Conducts electricity and makes work with energized electrical equipment dangerous.
Knowledge Check 2
1. Water can absorb large amount of heat before turning to steam
2. Water is reactive to certain combustible metals
3. As water's surface area increases, its heat absorption increases
4. Water has a high surface tension - Advantage
1&3
Disadvantage
2&4
Water Pressure - Column of water
one inch (W) x one inch (L) x 12 inches (H) = 0.434 psi
12 inches (W) x 12 inches (L) x 12 inches (H) = 0.434 psi
one inch (W) x one inch (L) x 24 inches (H) = 0.868 psi
Characteristics of Water Pressure - B = Bottom
, E = Equal
D = Depth
P = Perpendicular
A = All
D = Density
Characteristics of Water Pressure Definitions - Bottom = Pressure at the bottom of a container
Equal = Pressure transmitted to a confined amount of water is transmitted equally in all directions.
Depth = Pressure of water in an open container is proportional to its depth
Perpendicular = Pressure on an amount of water is perpendicular to any surface it acts on
All = At any point in the water in a container, pressure is equal in all directions, including upwards.
Density = Pressure of a liquid in an open container is proportional to the density of the liquid. The
density of a liquid refers to the material's weight compared to that of an equal quantity of water. Water
is given the weight of "one"; other materials are either lighter (<1) or heavier than water (>1).
Knowledge Check 3
You're presented with a column of water three feet by three feet, with a height of one foot. The water
pressure of this column equals: - A. 0.145 psi
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