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ASPE CPD Study Questions AH.
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ASPE CPD Study Questions AHFront - 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.
The sizing for indirect wastes is the same as direct-waste connections with what exception?
- correct answer-Due to the low velocities usually present in indirect wastes, stoppages are
more prevalent, and cleanouts should be provided at every possible location.
For an indirect waste, the discharge outlet should be what? - correct answer-A minimum of
1.5 times the indirect pipe size above the flood level of the receptacle.
How can the fixture unit flow rate be calculated? - correct answer-By dividing the total
discharge flow in gallons per minute of a single fixture divided by 7.5 gal/ft^3
What factors do FUs account for? - correct answer-Application in conjunction with the
probability of simultaneous use of fixtures.
For interior drainage systems, the rate of flow in a fixture drain should be what? - correct
answer-The same as the rate of flow discharged at the fixture outlet.
For interior drainage systems, the minimum fixture drain size is what? - correct answer-The
minimum size of the fixture trap (often given in a table)
What is the recommended value of n, the coefficient of roughness, for storm drains of all
sizes? - correct answer-0.0145
The designer must know what as related to the sewer, water, and gas inverts and locations?
- correct answer-The actual elevation of all of the floors of the building.
What is the minimum velocity of flow to achieve scouring action in piping? For keeping
grease in suspension in greasy wastes? For suspension in Storm Sewers? - correct
answer-2 fps, 4 fps, 3 fps. Dont forget to limit the length of runs for 1-1/2 and 2” pipe to
maintain scouring action.
What is the conversion for uniform flow velocity and capacity in sloping pipe going from from
1/4 in/ft slope to 1/8 in/ft? 1/2 in/ft? - correct answer-0.707 and 1.414
The hydraulic mean depth of flow or hydraulic radius is what ratio and what value? - correct
answer-The ratio of the cross sectional area of flow to the wetted perimeter of pipe surface,
expressed as D/4 where D is diameter in feet. It is the same ratio for full and half flow.
How is the quantity “rate of flow” expressed? - correct answer-Cross sectional area of
flow times the average velocity.
What formula determines the velocity of uniform flow in sloping drains? - correct answer-The
Manning Formula
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