Chapter 4 - Water Supply Systems Flashcards
Despite the development of many new innovations and techniques for controlling and fighting fires, _________ continues to be the primary extinguishing agent.
water
p 77
Three reasons water is used as the primary extinguishing agent:
*
*
*
- availability
- affordability
- effectiveness
p 77
Water is _________ and has its ________ density close to its freezing point.
heaviest / highest
p 78
Water is __________ and has its _________ density close to its boiling point.
lightest / lowest
p 78
For fire protection purposes, ordinary fresh water is generally considered to weigh _____ lb/ft^3 or ______ pounds per gallon.
62.4 / 8.34
p 78
The primary way water extinguishes fire is by _________, namely ____________ _______ from the fire.
cooling / absorbing heat
p 78
Another way water extinguishes is _____________, which occurs when _________ is excluded from the fire.
smothering / oxygen
p 78
Smothering works especially well on the surface of burning liquids that are __________ than water.
heavier
p 78
__________ _________ is a measure of the heat absorbing capacity of a substance, which means the amount of heat required to change a unit quantity of a substance by 1 degree in temperature.
Specific heat
p 79
The amount of heat transfer is usually measured in _________ __________ ________ or in the International System of Units (SI) as _________.
British thermal units (Btu) / joules
p 79
A ______ is the amount of heat required to raise the temperature of 1 lb of water 1*F.
Btu
p 79
The _______, also a unit of work, has taken the place of the calorie in the SI heat measurement.
joule
p 79
The ratio between the amount of heat needed to raise the temperature of a specified quantity of a material and the amount of heat needed to raise the temperature of an identical quantity of water by the same number of degrees ?
Specific heat
p 79
This is the quantity of heat absorbed by a substance when it changes from a liquid to a vapor ?
latent heat of vaporization
p 79
The temperature at which a liquid absorbs enough heat to change to vapor is known as the ?
boiling point
p 79
In fire fighting terms, if water from a 100 gpm fog nozzle is projected into a highly heated area, it can absorb approximately ___________ Btu of heat per minute if all of the water is converted to steam.
934,600 Btu
p 80
The speed with which water absorbs heat increase in proportion to the _________ _________ exposed to the heat.
water surface
p 80
If water is divided into _______ _______, the rate of heat absorption increases hundred of times.
many drops
p 80
_____________ helps cool the fire by driving heat and smoke from the area.
Expansion
p 81
The _____________ of the fire area will determine the amount of heat expansion. At _____ *F, water expands approximately ________ times its original volume.
temperature / 212 / 1700
p 81
The density of liquids in relation to water is known as ________ _________. Water is given the value of _____.
specific gravity / 1
p 81
Liquids with a specific gravity less than 1 are _________ than water and therefore ?
lighter / float on water
p 81
Liquids with a specific gravity greater than 1 are _________ than water and will ?
heavier / sink to the bottom
p 81
If the other liquid also has a specific gravity of 1, it ?
mixes evenly with water
p 81
Most flammable liquids have a specific gravity of ?
less than 1
p 81
Advantages of water:
* _______ - __________ capacity - Water has a greater ______ - __________ capacity than other common extinguishing agents due to the relatively large amount of heat required to change water to ________.
- Heat-absorbing / heat-absorbing / steam
p 81
Advantages of water:
* _________ _______ - Water applied to a fire by fog patterns and deselected solid streams greatly increases its _________ _______ and causes heat to be absorbed more rapidly.
- Surface area / surface area
p 81
Advantages of water:
- ____________ - In most areas, water is plentiful and readily __________.
- _______ - Water is relatively inexpensive when compared to other commercially available extinguishing agents.
- Availability / available
- Cost
p 81
Disadvantages of water:
- _______ __________ _________ - Water does not readily soak into dense materials.
- ____________ - Water is ___________ with certain substances such as combustible metals.
- Low _________ and _____________ - Water allows radiant heat to easily pass through it.
- ___________ point - In cold climates, ice may form in and on equipment, causing the potential for malfunction.
- High surface tension
- Reactivity / reactive
- opacity and reflectivity
- Freezing
p 81-82
Disadvantages of water:
- ______________ - Water __________ electricity, which can be a hazard when fire fighting operations are taking place around energized electrical equipment.
- ______________ runoff - Water can carry ______________ away from the fire scene.
- _________ - Excessive water __________ can contribute to structural instability.
- Conductivity / conducts
- Contaminated / contaminants
- Weight / weight
p 82
In fire service terminology, _________ refers to the force that moves water through a conduit - either a pipe or hose.
pressure
p 82
A 1 in^2 column of water 1 ft high exerts a pressure _______ psi at its base.
0.433 psi
p 82
Six principles of pressure:
- First Principle: Fluid pressure is ______________ to any surface in which it acts.
- Second Principle: Fluid pressure at a point in a fluid at rest is the same intensity in ______ ___________ - In other words, fluid pressure at a point in a fluid at rest has no ___________.
- perpendicular
- all directions / direction
p 83
Principles of pressure:
- Third principle: Pressure applied to a confined fluid will be transmitted _________ in all directions.
- Fourth principle: The pressure of a liquid in an open vessel is proportional to its ________
- equally
- depth
p 83
Principles of pressure:
- Fifth principle: The pressure of a liquid in an open vessel is proportional to the ________ of the liquid.
- Sixth principle: The pressure of a liquid on the bottom of a vessel is independent of the _________ of the vessel.
- density
- shape
p 84
Principles of pressure:
Regardless of the shape of the container and its opening, the ____________ of the water column is the same for a given height.
pressure
p 84
Atmospheric pressure is greatest at ?
low altitudes
p 85