87 Questions
What is the primary mission of the District of Columbia Fire and Emergency Medical Service Department according to the passage?
To preserve life and promote health and safety through excellent pre-hospital treatment and transportation, fire prevention, and rescue activities
What is the vision of the DC Fire and Emergency Medical Services Department according to the passage?
All of the above
What is the purpose of the 'G.O. 2012-13' mentioned at the end of the passage?
It is a directive or order issued by the Department in 2012-13
Which of the following is NOT mentioned as part of the Department's mission or vision?
Providing the highest quality of fire suppression activities
What is the primary focus of the DC Fire and Emergency Medical Services Department's vision according to the passage?
All of the above
According to the passage, which of the following is a specialized area within the general field of hydraulics?
Hydrostatics
What is the main focus of the fire service's interest in the subject of hydraulics according to the passage?
The delivery of water in sufficient quantities to extinguish fires
What is the key danger mentioned in the passage that experienced firefighters recognize while operating a hose line?
Excessive nozzle pressure
According to the passage, which of the following is a specialized area of hydraulics that deals with the motion and action of liquids?
Hydrodynamics
According to the passage, which of the following is a specialized area of hydraulics that deals with the pressure and equilibrium of liquids?
Hydrostatics
What is the main purpose of the fire service's interest in the subject of hydraulics according to the passage?
To deliver water in sufficient quantities to extinguish fires
What fundamental principle of hydraulics is described by Pascal's Law?
Pressure is transmitted equally in a confined fluid
Why does a liquid remain at rest within a container?
Balance of forces along horizontal planes
Which property of water plays a crucial role in fire service hydraulics?
Incompressibility
What would happen to a flexible hose if pressure was not equally exerted on it?
It would collapse
How does the pressure of water in an open container change with depth?
Directly proportional to its depth
What is the weight of a cubic foot of water according to the text?
$62.5$ pounds
What force is required to reduce the volume of water by one percent?
$30,000$ pounds per square inch
'Pressure is defined as a force divided by the area over which it is distributed.' This statement implies that:
Pressure is directly related to force and inversely related to area
What geometric shape does a flexible hose assume when pressure is exerted equally on it?
Circular
In what way does Pascal's Law state pressure acts within a confined fluid?
Transmits with no loss equally to every part
What determines the friction loss in a hose line according to the passage?
The velocity of the water
What is the relationship between the pressure and the flow rate in a hose line according to the passage?
The pressure and flow rate are independent
How does the friction loss change along the length of the hose line according to the passage?
The friction loss increases linearly with distance
What is the effect of atmospheric pressure on the hydraulic system according to the passage?
Atmospheric pressure accelerates the water's entrance into the pump
How does the velocity of the water change along the length of the hose line according to the passage?
The velocity remains constant along the entire length
What is the purpose of the nozzle mentioned in the passage?
To deliver a specific flow rate at a given pressure
How does the pressure change along the length of the hose line according to the passage?
The pressure decreases linearly with distance
What is the relationship between the pressure and the friction loss in the hose line according to the passage?
The friction loss is independent of the pressure
What is the purpose of the pumper mentioned in the passage?
To discharge water into the hose line at a specific pressure
How does the atmospheric pressure change with elevation according to the passage?
Atmospheric pressure decreases linearly with elevation
What is the pressure at the base of a 2-foot column of water?
0.868 pounds per square inch
What is the pressure at the base of a 3-foot column of water?
1.302 pounds per square inch
What is the pressure at the base of a 20-foot column of water?
8.68 pounds per square inch
What is the formula to calculate the pressure in pounds per square inch (P) given the head (h) in feet?
P = 0.434 x h
What is the formula to calculate the head (H) in feet given the pressure (P) in pounds per square inch?
H = 2.304 x P
What is the height of a column of water that would produce exactly 1 pound per square inch of pressure?
2.304 feet
What is the pressure in pounds per square inch at the base of a column of water 35 feet high?
15.19 PSI
How does the shape of the container affect the downward pressure of water?
The shape of the container does not affect the downward pressure of water at all.
What is the pressure on the 6th floor of the standpipe system shown in Figure 7?
135 PSI
What is the engine pressure of the pumper connected to the standpipe system in Figure 7?
185 PSI
What is the weight of one U.S. gallon of water according to the passage?
8.35 pounds
What is the relationship between a cubic foot and a U.S. gallon according to the passage?
One cubic foot equals 7.481 U.S. gallons
Why is it necessary to position a pump at some distance above the level of water according to the passage?
Water has no tensile strength and cannot be pulled upward
What is the purpose of the physical connection between the pump and the water level mentioned in the passage?
To provide a pathway for the water to flow from the water level to the pump
What is the term used to describe the process of a pump drafting water from an open body of water located below the intake of the pump?
Suction lift
According to the passage, what is the relationship between a cubic foot and cubic inches?
$1 ext{ cubic foot} = 1728 ext{ cubic inches}$
What is the pressure loss per floor above the pump according to the text?
5 PSI
What is the pressure loss for 200 feet of 1 1/2" hose with a CVFSS nozzle?
135 PSI
What is the purpose of the check valves in the standpipe system?
To prevent backflow from the standpipe into the municipal supply
What happens when the pressure being delivered to the FDC is greater than the back-pressure on the clapper?
The clapper will open, allowing water from the pumper to enter the system
How does an increase in pressure at the pumper affect the pressure throughout the system?
It causes an increase in pressure at every other point in the system
What happens to the static pressure in the standpipe when a hose line is placed in service?
The static pressure decreases due to the friction loss in the supply lines and the standpipe
How does the introduction of motion or flow patterns affect the basic hydraulics of the system?
It causes a loss of kinetic energy that must be compensated for
What is the relationship between viscosity and the speed of different liquids?
Liquids with lower viscosity move faster in response to the same forces
What is the primary reason that mathematical solutions alone are often not sufficient for understanding flow phenomena?
Mathematic solutions are incomplete and cannot fully capture the complexity of flow dynamics
What is the relationship between potential energy and kinetic energy when motion is introduced in a liquid system?
Potential energy is partially converted to kinetic energy, with some energy being dissipated as heat
What is the primary purpose of a Pitot tube?
To measure the velocity and pressure heads present within a flowing stream
Which of the following gauges is used primarily on fire apparatus?
Bourdon gauges
What is the primary advantage of Bourdon gauges over other types of gauges?
They are compact and sturdy
What is the difference between a gauge that measures pressure only and a compound gauge?
A compound gauge measures both pressure and vacuum, while a pressure-only gauge measures only pressure
What do the calibrations on a gauge that measures vacuum only represent?
Inches of mercury
What is the relationship between the weight and quantity of water?
One cubic foot of water weighs 62.5 pounds and occupies a space of 1728 cubic inches
How many gallons of water are contained in one cubic foot?
7.481 gallons
What is the difference between a gauge that reflects relative pressure and one that reflects absolute pressure?
A gauge that reflects relative pressure is adjusted so that the needle pointer is at zero when only atmospheric pressure is present, while an absolute pressure gauge is not
What is the primary advantage of using a gauge that reflects relative pressure on fire apparatus?
It provides a constant source of information concerning the pressures present at different locations within the pump, relative to atmospheric pressure
What is the purpose of using different calibrations on gauge dials for measuring pressure, vacuum, and both?
It allows for easier identification of the type of measurement being taken
What is the relationship between the diameter of a hose and the velocity of water flow?
As the diameter decreases, the velocity increases.
Which factor contributes to the creation of heat due to water flow?
Internal fluid resistance
How does friction loss vary in relation to the diameter of a hose for the same discharge?
Friction loss varies inversely with the diameter to the power of five.
How does friction loss vary with the velocity of water flow within one given size of hose line?
Friction loss varies as the square of velocity increase.
What effect does increasing the size of a hose have on friction loss?
Decreases friction loss
How does length affect friction loss within one given size of a hose line?
Friction loss varies directly with length.
What contributes to friction loss in addition to internal fluid resistance?
"Bends in hose lines" and other factors like valves and rough interior linings
What impact does doubling the flow velocity have on friction loss within one given size of hose line?
Friction loss quadruples
In terms of friction loss, how would a hose line delivering a flow of 200 gallons per minute measuring 100 feet compare to an identical line measuring 200 feet?
The 100-foot line would have double the friction loss.
What causes greater 'friction loss' according to the passage?
Rubbing caused by faster water movement
What is the primary cause of resistance to movement in a liquid with high viscosity?
The natural attraction between the molecules in the liquid
What is the effect of an increase in velocity on the flow of a liquid?
It causes the flow to become more turbulent
What is the primary cause of friction loss in hydraulic systems?
The motion of the liquid along a smooth or rough surface
How does the velocity of flow in a carrier (such as a river or hose) change when the cross-sectional area of the carrier varies?
The velocity increases at narrower parts of the carrier and decreases at wider parts
What is the relationship between the volume and velocity of flow in a hydraulic system?
Volume and velocity are closely related and vary inversely with each other
What is the main factor that determines whether the flow of a liquid will be streamlined or turbulent?
The velocity of the liquid flow
What is the primary source of resistance to the motion of a liquid when it is in contact with a solid boundary?
The molecular friction between the liquid and the solid surface
What is the primary cause of eddy loss in a hydraulic system?
Abrupt changes in the flow of the liquid
Which of the following is NOT mentioned in the passage as a factor that can affect the transition from streamlined to turbulent flow in a liquid?
A decrease in the roughness of the carrier
What is the primary purpose of the concept of friction loss in hydraulics?
To quantify the reduction in pressure created by a pump due to the motion of the liquid
Learn about the mission and vision statements of the District of Columbia Fire and Emergency Medical Service Department and their goals for preserving life, promoting health and safety, and enhancing homeland security awareness.
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