Flashcards in Chapter 6 What is Water and Where Does It Come From Deck (60):
Water is a compound of hydrogen and oxygen formed when:
two hydrogen atoms combine with one oxygen atom.
Water exists in a liquid state between:
32ºF and 212ºF (0ºC and 100ºC)
Water converts to a solid state (ice) below:
Water converts to steam above:
Water is lightest close to its boiling point – weighing approximately:
60 lb/ft3 (0.96 kg/L).
For fire protection purposes, ordinary fresh water is generally considered to weigh:
8.33 lb/gal (1kg/L)
What is specific heat?
A measure of the heat-absorbing capacity of a substance
What unit is used to measure amounts of heat transfer?
British thermal unit (Btu) or joule (J)
What is a Btu?
The heat required to raise the temperature of 1 pound of water 1ºF
What unit of measurement has the joule taken the place of in the SI (International System of Units)?
The latent heat of vaporization is:
The quantity of heat absorbed by a substance when it changes from a liquid to a vapor
What is the name for the temperature at which a liquid absorbs enough heat to change to a vapor?
Vaporization does not completely occur at boiling point. Each pound of water requires approximately ___ Btu (kJ) of additional heat to completely convert into steam.
970 Btu (1 023 kJ)
Approximately how much does water expand beyond its original volume when converted to steam at 212ºF (100ºC)?
The speed with which water absorbs heat increases in proportion to:
the water surface exposed to the heat.
Steam expansion is ___ inside a burning building.
What is specific gravity?
The density of liquids in relation to water
What kinds of liquids are lighter than water and therefore float on water?
Those with a specific gravity less than 1
What kinds of liquids are heavier than water and sink to the bottom?
Those with a specific gravity greater than 1
Most flammable liquids have a specific gravity of:
less than 1
How much pressure is required to reduce the volume of water one percent?
30,000 psi (210 000 kPa)
Friction loss in a system ___ as the length of hose or piping ___.
Flow pressure will always be ___ near the supply source and ___ at the farthest point in the system.
If an opening is made directly at the hydrant, as opposed to the nozzle, the flow will be much ___ at a ___ pressure.
If velocity is increased beyond practical limits, the friction becomes so great that resistance agitates the entire stream, creating:
What is water hammer?
The sudden stopping of water moving through a hose or pipe resulting in an energy surge being transmitted in the opposite direction, often at many times the original pressure
Close nozzles, hydrants, valves, and hose clamps ___ to prevent water hammer.
Equip apparatus inlets and remote outlets with ___ to prevent damage to equipment.
pressure relief devices
High-volume systems should be protected with:
Where can the primary water supply be obtained?
Surface water or groundwater
Which of the following is NOT a means of moving water?
A. Gravity system
B. Treatment system*
C. Combination system
D. Direct pumping system
Which means of moving water uses one or more pumps that take water from the primary source and discharge it through the filtration and treatment processes?
Direct pumping system
Which means of moving water uses a primary water source located at a higher elevation than the distribution system?
What is the fire department's main concern regarding treatment facilities?
hat a maintenance error, natural disaster, loss of power supply, or fire could disable the pumping stations
From where does the water supply distribution system receive water?
From the pumping station
When water flows through pipes, its movement causes friction that results in a reduction of pressure. There is much less pressure loss in a water distribution system when fire hydrants are supplied:
from two or more directions.
A fire hydrant that receives water from only one direction is known as a:
A fire hydrant that receives water from two or more directions is known as a:
A distribution system that provides circulating feed from several mains constitutes a:
___ are large pipes (mains) with relatively widespread spacing, that convey large quantities of water to various points of the system for local distribution to the smaller mains.
___ make up a network of intermediate-sized pipes that reinforce the grid within the various loops of the primary feeder system and aid the concentration of the required fire flow at any point.
___ make up a grid arrangement of smaller mains serving individual fire hydrants and blocks of consumers.
To ensure sufficient water, two or more primary feeders should run from the source of supply to the ___ districts of the community by separate routes.
high-risk and industrial
In residential areas, the recommended size for fire hydrant supply mains is at least 6 inches (150 mm) in diameter. These should be closely gridded by 8-inch (200 mm) cross-connecting mains at intervals of not more than:
600 feet (180 m).
In the business and industrial districts, the minimum recommended size is a(n) ___ main with cross-connecting mains every 600 feet (180 m).
8-inch (200 mm)
___ mains may be used on principal streets and in long mains not cross-connected at frequent intervals.
12-inch (300 mm)
Water mains as large as ___ may be found in major cities.
48 inches (1.2 m)
What is the function of a valve in a water distribution system?
To provide a means for controlling the flow of water through the distribution piping
Valves should be operated at least ___ to keep them in good condition.
once a year
Valve spacing should be such that:
only a minimum length of pipe is out of service at one time.
Which type of valve shows whether the gate or valve seat is open, closed, or partially closed?
Which type of valve is a hollow metal post that is attached to the valve housing?
Post indicator valve
Which type of valve has a yoke on the outside with a threaded stem that controls the gate's opening or closing?
Outside screw and yoke
Which types of valves are the most common types of valves used on most public water distribution systems?
Valves that are only partially open cause:
high friction loss.
Which of the following is NOT a material commonly used to make water pipes?
D. Cast iron
Friction loss of pipes is most frequently increased by:
encrustation of minerals on the interior surfaces of the pipe.
Friction loss can be reduced by:
flushing hydrants periodically.
Private water supply systems are NOT normally found on:
fire protection properties.