ASPE CPD Study Questions AH and 100% Correct
Answers
Where should cleanouts be provided? - ✔✔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? - ✔✔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? - ✔✔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? - ✔✔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? - ✔✔2 FUs, sump pumps, ejectors, air
conditioning equipment, water cooled, equipment, etc
,What minimum slopes are required for building drains and why? - ✔✔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? - ✔✔1/2 full to 3/4 full max under
uniform flow conditions
What is a house (building) drain? - ✔✔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? - ✔✔45 degrees
Does an interior drainage stack that offsets 45 degrees or less from the vertical require a
change in size? - ✔✔No. Any more than a 45 degree offset requires sizing the offset
as a house drain.
What is a branch interval? - ✔✔A building story or a distance between two branch
connections greater than 8 feet apart.
Describe the procedure for sizing interior drainage stacks. - ✔✔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? - ✔✔7/24 of
the total cross sectional area of the stack.
Where should and shouldn’t you connect branch connections to stack offsets? -
✔✔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? - ✔✔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? - ✔✔45 degrees
When does terminal velocity occur in a drainage stack? - ✔✔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? -
✔✔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? - ✔✔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? - ✔✔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? - ✔✔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? - ✔✔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? - ✔✔A Stack.
Properties of uniform flow apply to branches of what length and longer? - ✔✔5 feet
Special wastes, tank overflows, tank emptying lines, releif valve discharges, etc. should
discharge where and why? - ✔✔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? - ✔✔140F
When interior drainage piping developed length reaches 100 feet, what should happen
and why? - ✔✔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.
Answers
Where should cleanouts be provided? - ✔✔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? - ✔✔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? - ✔✔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? - ✔✔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? - ✔✔2 FUs, sump pumps, ejectors, air
conditioning equipment, water cooled, equipment, etc
,What minimum slopes are required for building drains and why? - ✔✔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? - ✔✔1/2 full to 3/4 full max under
uniform flow conditions
What is a house (building) drain? - ✔✔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? - ✔✔45 degrees
Does an interior drainage stack that offsets 45 degrees or less from the vertical require a
change in size? - ✔✔No. Any more than a 45 degree offset requires sizing the offset
as a house drain.
What is a branch interval? - ✔✔A building story or a distance between two branch
connections greater than 8 feet apart.
Describe the procedure for sizing interior drainage stacks. - ✔✔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? - ✔✔7/24 of
the total cross sectional area of the stack.
Where should and shouldn’t you connect branch connections to stack offsets? -
✔✔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? - ✔✔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? - ✔✔45 degrees
When does terminal velocity occur in a drainage stack? - ✔✔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? -
✔✔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? - ✔✔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? - ✔✔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? - ✔✔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? - ✔✔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? - ✔✔A Stack.
Properties of uniform flow apply to branches of what length and longer? - ✔✔5 feet
Special wastes, tank overflows, tank emptying lines, releif valve discharges, etc. should
discharge where and why? - ✔✔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? - ✔✔140F
When interior drainage piping developed length reaches 100 feet, what should happen
and why? - ✔✔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.
