FINAL EXAM | ACTUAL EXAM QUESTIONS AND CORRECT ANSWERS |
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Question 1
What does one cubic foot of water weigh?
A) 8.35 lbs
B) 14.7 lbs
C) 62.5 lbs
D) 7.5 lbs
E) 231 lbs
Correct Answer: C) 62.5 lbs
Rationale: According to standard measurements used in fire hydraulics, one cubic foot of
water weighs 62.5 pounds.
Question 2
How many cubic inches are contained in one cubic foot of water?
A) 231
B) 1,728
C) 7.5
D) 62.5
E) 2.304
Correct Answer: B) 1,728
Rationale: One cubic foot is a standard unit of volume, and it contains 1,728 cubic inches (12
inches x 12 inches x 12 inches).
Question 3
How many gallons of water are in one cubic foot?
A) 1.13
B) 8.35
C) 14.7
,D) 7.5
E) 62.5
Correct Answer: D) 7.5
Rationale: A standard conversion in fire hydraulics is that one cubic foot of volume holds
approximately 7.5 gallons of water.
Question 4
What is the approximate weight of one gallon of water?
A) 62.5 lbs
B) 7.5 lbs
C) 14.7 lbs
D) 8.35 lbs
E) 0.434 lbs
Correct Answer: D) 8.35 lbs
Rationale: One U.S. gallon of fresh water weighs approximately 8.35 pounds. This is a
fundamental constant for hydraulic calculations.
Question 5
One U.S. gallon of water contains how many cubic inches?
A) 1,728
B) 62.5
C) 231
D) 7.5
E) 8.35
Correct Answer: C) 231
Rationale: The standard U.S. gallon is defined as a volume of 231 cubic inches.
Question 6
How much pressure does a one-foot column of water exert?
A) 1.000 psi
,B) 2.304 psi
C) 0.434 psi
D) 14.7 psi
E) 1.13 psi
Correct Answer: C) 0.434 psi
Rationale: For every foot of vertical elevation (head), a column of water exerts a back pressure
of 0.434 psi. This is crucial for calculating head pressure or pressure loss due to elevation.
Question 7
How high can one pound per square inch (psi) of pressure elevate a column of water?
A) 0.434 feet
B) 1.13 feet
C) 2.304 feet
D) 14.7 feet
E) 34 feet
Correct Answer: C) 2.304 feet
Rationale: One psi has enough force to lift a column of water to a height of 2.304 feet. This is
the inverse of the head pressure calculation.
Question 8
What is the atmospheric pressure at sea level?
A) 0 psi
B) 10 psi
C) 14.7 psi
D) 34 psi
E) 62.5 psi
Correct Answer: C) 14.7 psi
Rationale: Standard atmospheric pressure at sea level is 14.7 psi. This is the pressure that
allows a fire pumper to draft water.
, Question 9
Theoretically, what is the maximum height that water can be lifted for drafting at sea level?
A) 10 feet
B) 14.7 feet
C) 25 feet
D) 34 feet
E) 62.5 feet
Correct Answer: D) 34 feet
Rationale: The maximum theoretical lift is calculated by converting atmospheric pressure
(14.7 psi) into feet of head (14.7 psi x 2.304 ft/psi ≈ 33.87 feet). For practical purposes, this is
rounded to 34 feet.
Question 10
How many feet of lift are created by one inch of mercury (Hg) on a vacuum gauge?
A) 0.434 feet
B) 1.00 feet
C) 1.13 feet
D) 2.304 feet
E) 14.7 feet
Correct Answer: C) 1.13 feet
Rationale: During drafting operations, each inch of mercury measured on the compound
gauge (in vacuum) corresponds to approximately 1.13 feet of vertical lift.
Question 11
What is the recommended minimum pressure that should be maintained on the compound
gauge when operating from a hydrant?
A) 0 psi
B) 5 psi
C) 10 psi