ASPE CPD Study Questions AH with Complete
Solutions.
Front - Correct Answer Back
What is the specific weight of water? - Correct Answer 62.4 lbs per cubic foot
What happens in a storm and sanitary system after it passes the water test? - Correct
Answer A smoke pressure test is recommended with a smoke pressure of 1 in wc to prove
the system gas tight.
Is an air test acceptable for a storm and sanitary system? - Correct Answer Yes, if a water
test is not possible, at a pressure of 5 psi, are tests are impractical and costly
What are the testing procedures for the storm and sanitary system? - Correct Answer A
water test upon completion of the rough piping and prior to concealment of 10 ft wc
minimum (except the topmost 10 feet of pipe), not to exceed 100 ft wc. If system is higher
than 100 feet, test plugs must be installed to facilitate testing, rarely are more than 7
stories tested at one time. A peppermint oil test may also be done with 2 oz of peppermint
oil and 10 qt boiling water, and searching for peppermint smell at leaks, however it is
difficult to pinpoint the leak by this method
The maximum length from the vent connection to any future drain outlet is required by
code, why, how long is the distance (listed in the book), and what’s the exception? -
Correct Answer To prevent a dead end where slime, sludge and fungi can grow, 2 feet,
unless the piping must be extended to an accessible location for a cleanout
A sanitary tee may be used in the vertical but what may not be used in the vertical and
why? - Correct Answer A double sanitary tee because the possibility of flow crossover and
excessive pressures when one branch is discharging and the other isn’t are possible
What are the slopes of pipe inside the building that correspond to 2 fps velocity? - Correct
Answer 1/4 in per foot for 3 in and smaller 1/8 in per foot for larger pipe all elbows, taps,
tees etc are tapped at a pitch of 1/4” per foot
Where should cleanouts be provided? - Correct Answer 1) Inside or outside the building at
the point of exit (use a wye branch) 2) at every change in direction greater than 45
degrees 3) every 50 feet for piping 4” and less, and 100 ft for larger piping 4)
,underground piping larger than 10 in should be provided with manholes at every change in
direction and every 150 feet 5) at the base of all stacks 6) as required by code
What size cleanouts are provided in piping? - Correct Answer Piping up to 4 inches, the
cleanout is the same size as the pipe. Piping greater than 4 inches, 4 inch cleanouts are
adequate.
What should be installed in the house drain if there is a danger of backflow of sewage into
the building? Whats the difference? - Correct Answer A backwater valve or a combination
BWV with manually operated gate valve. The BWV does not interfere with the airflow
throughout the system, and the gate valve is recommended where there is a history of
backflow as a positive means of protection.
Branch connections to the house drain should be made where and why? - Correct Answer
At the upper portion of the pipe (above the 1/2 - 2/3 full mark) because: 1) there is a lower
chance of stoppages in the branch 2) there is less flow interference at the point of
connection 3) When there is no flow in the branch, the full area of the pipe is available to
relieve pneumatic pressure fluctuations in the house drain
How many fixture units are equivalent to 1 gpm continuous or semicontinuous flow and
what are examples of these types of flow? - Correct Answer 2 FUs, sump pumps, ejectors,
air conditioning equipment, water cooled, equipment, etc
What minimum slopes are required for building drains and why? - Correct Answer 3 in
pipe and smaller: 1/4 in/ft 4-6 in pipe: 1/8 in/ft 8 in pipe and larger: 1/16 in/ft to maintain 2
fps scouring action if low flow fixtures are present, 1/4 in/ft for all is a good idea
House drains are designed to flow how full? - Correct Answer 1/2 full to 3/4 full max under
uniform flow conditions
What is a house (building) drain? - Correct Answer The lowest piping of a gravity drainage
system that receives the discharge from soil, waste, and other drainage pipes inside the
building that extends a short distance from the building and conveys the drainage to the
building sewer
What is the measurement from horizontal that separates horizontal and vertical drainage
stacks? - Correct Answer 45 degrees
,Does an interior drainage stack that offsets 45 degrees or less from the vertical require a
change in size? - Correct Answer No. Any more than a 45 degree offset requires sizing the
offset as a house drain.
What is a branch interval? - Correct Answer A building story or a distance between two
branch connections greater than 8 feet apart.
Describe the procedure for sizing interior drainage stacks. - Correct Answer 1) First size
the horizontal branches connecting to the stack 2) Determine the minimum size that will
accept each branch at one branch interval 3) Total all fixture units connected to the stack,
and determine the size. The minimum size must be at least equal to the largest diameter
required at the base. You may reduce in size at upper branch intervals, but never by more
than 1/2 the largest size.
What is the total recommended maximum permissible flow in a stack? - Correct Answer
7/24 of the total cross sectional area of the stack.
Where should and shouldn’t you connect branch connections to stack offsets? -
Correct Answer Not to the horizontal offset to the stack if at all possible, unless its at least
10 pipe diameters downstream, and ideally 2 feet above the offset or 2 feet below to avoid
pressure fluctuations.
What can minimize hydraulic jump? - Correct Answer Increasing the slope of the
horizontal drain. Connecting to a horizontal drain that is larger than the stack.
Any offset of the stack greater than what can cause hydraulic jump? - Correct Answer 45
degrees
When does terminal velocity occur in a drainage stack? - Correct Answer It is achieved at
approximately 10 - 15 fps and this velocity is achieved within 10 - 15 feet of fall from the
point of entry.
A drainage stack should never be designed for a capacity greater than what and why? -
Correct Answer One-thrid full, because the pressure fluctuations in the system could
greatly exceed the maximum 1 in water column criterion and lose their seal by siphonage
blowout
, What is one positive and one negative of a tee-wye fitting? - Correct Answer The long
radius tee-wye fitting gives the water a greater downward component than a sanitary tee,
but also has a greater probability of siphoning the traps
How are horizontal branch connections to the stack made? - Correct Answer With a
sanitary tee (a short radius tee-wye, vertical position only) or with a long radius tee-wye
(vertical or horizontal position). (The tee-wye is also called a combination wye and one-
eighth bend)
What is the difference between soil stacks and waste stacks? - Correct Answer Soil stacks
collect wastes that contain fecal matter, and waste stacks collect wastes that do not
contain fecal matter (lavatories, sinks, etc)
What is a vent stack? - Correct Answer A vent stack prevents the development of
excessive pressures in the lower regions of the drainage stack by relieving the air that is
rapidly carried down the drainage stack. It does not include vertical fixture drains and
branch vents that do not pass through more than two stories before being connected to
the soil or waste stack or vent stack.
What is a general term for any vertical line of soil or waste piping that collects water and
wastes from fixture drains and horizontal branch drains from two or more floors of a
building? - Correct Answer A Stack.
Properties of uniform flow apply to branches of what length and longer? - Correct Answer
5 feet
Special wastes, tank overflows, tank emptying lines, releif valve discharges, etc. should
discharge where and why? - Correct Answer Through an air break to an appropriate
receptacle (floor drain or other) to prevent overpressurization of the drainage system.
High temperature wastes should be cooled to what temperature before discharging into
the drainage system? - Correct Answer 140F
When interior drainage piping developed length reaches 100 feet, what should happen
and why? - Correct Answer A vent to atmosphere should be provided. It should run
independently through the roof, this is to prevent the rapid fouling of the pipe due to the
growth of slime and fungi in the absence of air circulation.
