DWV Flashcards
What is a Fixture Outlet Pipe?
Is the section of drain pipe bn the drain outlet of a fixture and the trap serving it.
What is the max length of a fixture outlet pipe? and why?
Max length = 4’ (1200mm)
Why? = Prevents velocity of the water draining via fixture outlet / siphoning the trap (aka self-siphonage)
What are the rules for a fixture drain in a 3 compartment commercial kitchen sink?
Fixture outlet pipe is increased in one size.
What is a P-trap about?
It is a non-mechanical device that prevents odours, animals / drafts from entering a building.
It should not affect the flow from the fixture when draining.
Why are there limitations to how far below the fixture a trap can be?
To control the velocity of water moving through the trap
-Too much velocity = self siphoning
Why does the trap arm have to be nominally horizontal?
Again, dt water velocity + self siphoning
Where would you find a integral trap?
Toilet and urinal. It is a trap that is built into the fixture
What is the pipe bn the trap weir + the vent pipe serving the fixture?
A trap arm
What is the min trap arm length?
Shall not be less than two pipe diameters
What does the max length depend on?
Size
The total fall of a trap arm shall not…
exceed one pipe diameter
What is a Fixture Drain?
the section of drainage pipe between pipe bn the outlet of a single fixture trap / another section of drainage system (ex: another fixture drain, a branch or a SOWS)
Tell me all about the Branch
A soil-or-waste pipe that serves at least 2 fixtures located on a single story
Downstream = connects to a stack, building drain, another branch or sewage sump.
Upstream = connects two fixture outlet pipes or fixture drains
SOWS EVERYWHERE (what is it?)
When a fixture drain or branch carries waste through at least one story.
Where must a clean out be located on a SOWS?
At the lowest vertical point
What must be located at the top of a SOWS?
Stack vent
What is a slug of water?
A high inflow rate of water that moves from horizontal –> vertical.
(branch/ fixture drain –> SOWS)
What is gravitational force?
When a sheet of water accelerates until frictional force (exerted by the pipe wall) = gravitational force
What is terminal velocity?
When falling water remains at a constant (when no additional flow enters the stack)
What is terminal lenght?
The distance that maximum velocity is achieved
Term. velocity of 3 - 4.5 m/s (10 to 15fps) achieves term length at 3 - 4.5m (10 -15ft)
What is Hydraulic jump mean in drainage?
When flow goes from vertical stack to a horizontal branch /building drain at stack term. velocity.
As the horizontal drain pipe increases the flow slowly decreases
What happens if a trap is installed to close to the base of the stack?
There’s potential for trap seal loss dt static pressure caused from turbulence (from hydraulic jump)
DT the above fixture drains / branches be prohibited from being connected to a branch or sanitary building drain within 1.5m (5’) of the bottom of the SOWS
What is a Sanitary Building drain?
- Connects to a sanitary building sewer at its downstream end
- Becomes the main horizontal sanitary collection pipe within the
building. - A c/o must be installed to serve the sanitary building sewer
Where should the c/o that serves the sanitary building sewer be installed?
On the 1m portion of the sanitary building drain outside the foundation wall.
Which part is considered the Sanitary Building Sewer?
Pipe that extends from the end of the Sanitary building drain (from 1m/39” outside the building)
Continues to either a public sewer, private sewer, on-site wastewater disposal system or other point of disposal.
Where is the c/o placed on a Sanitary Building Sewer?
Between the building wall + the main sewer
c/o is 4” w/ a water/gas tight cap
What prevents sewer pipes from settling / losing there grade?
Installing over compacted sand.
Who is in charge of installing the sewer from the property line to the sewer main?
Municipal sewer crew
Plumbers take care of pipe from foundation –> property line
What is a Sewage Sump Basin?
Used when fixtures are installed at a lower elevation than the gravity building drain.
What is another name for Sewage Sump Basin?
sub-drainage system
How does a Sewage Sump Basin work?
It lifts sewage up to the buildings gravity drain via automatic pump equipment.
True or False: A sewage sump basin must be airtight to prevent gas from escaping.
True
What is the min size of vent pipe to a sewage sump basin?
Vent pipe has to be one size smaller that the largest pipe that drains into sump.
Min size = 2 inches
Max size = 4 inches
How many sump pumps would a commercial building have?
2 (duplex), one as back up. If 2 pumps are needed at once then 3 (triplex) pumps would be installed.
How many sump pumps would a residential house have?
A single (simplex) pump. Flow here can easily be controlled by restricting usage.
What do c/o provide?
They provide access to all parts of a drainage system so that obstructions can be removed
What is the difference between a One-way rodding and a Two-way rodding?
One-way rodding = using a wye as a c/o
two-way rodding = using a line c/o or a manhole
What changes when line c/o or manholes are used?
allowable distances bn c/o doubles
When are Manholes used?
They are used for underground piping that is 8” or larger in diameter.
What is Benching mean?
Is when a concrete channel is poured to direct flow.
Is shaped like a half-pipe and is left open at the top, which allows access.
True or False: Manholes must be vented to open air when installed inside a building.
True!
What does Vent piping allow?
Allows the building to breathe which limits the pressure differential on trap seals (max 1” WC/ 250 Pa)
Also lessons the chance of trap seals being siphoned out.
What is an Individual vent?
A vent (duh) that serves only ONE fixture
Is connected to a horizontal trap arm.
How is an Individual vent connected? (3 points)
- Has to be installed into the trap arm in a nominally vertical
fashion. - May extend from fixture being served –> outside air w/o being
connected to other venting system. - May connect to another part of the venting system.
What are Dual vents about?
Serves TWO fixtures
A double symmetrical fitting must be used when connecting the 2 fixtures to the branch. (like a Wye)
Explain Continuous vents
Extends from a vertical SOWS
Can serve either one or two fixtures on the same storey
Where is the most common application of a Continuous vent?
Seen in wet-vented branches.
If a Continuous vent isn’t connected to either a dual or individual vent, it’ll be connected to either a fixture drain/wet vent or branch/wet vent.
Explain a Individual and Continuous vent
Serves only a single fixture connected to a vertical soil-or-waste pipe (using a single sanitary Tee) page 59 Learning task 3
Explain Dual and Continuous vent
Serves 2 fixtures that connect to a soil-or-waste pipe
(Uses double sanitary tee) Page 59 Learning task 3
Roughly explain Circuit venting… (You can do it!)
Is a method of commonly venting multiples of floor outlet fixtures (mostly w/c)
How are Circuit vents connected?
Connected to the trap arm of the most upstream fixture.
Once connected, it can either:
A) extend upward to open air
B) Tie into another vent that connects to open air
Page 60 Learning Task 3
What is a Relief vent?
Required in Circuit vented branches to assist w/ air circ. and to relieve pressure fluctuations dt fluid flow in the branch. (pg 60)
How are Additional Circuit vents used?
They are required on Circuit vents when:
a) There are more than 8 fixtures connected bn vent pipes
b) There is a cumulative change in direction of more than 45 degrees bn circuit vent / relief vent
What is an Offset relief vent?
- Provides additional air circ to a SOWS w/ a nominally
horizontal offset.
When is an Offset relief vent needed?
- If an offset is more than 60” (1.5m) long
- The upper portion of the stack passes through 3 or more storeys
- Has more than 100 fixtures on it.
How is an Offset relief vent connected?
At the lowest end of the upper stack (after last SOW connection)
At the upper end of the lower stack at a point that’s higher than any drain connection. (page 62)
What are Sump vents?
Serves the sewage sump basin only to ensure that the basin operates at atm pressure. (pg 63)
What are Branch vents?
- Is formed by combining 2 or more vent pipe.
- The vent pipes cannot be stack vents or vent stacks.
- Only some types of vents will become branch vents when tied into other vents.
What is a Stack Vent?
It is the main vent for the SOWS
Where does the Stack vent begin?
- At the highest fixture connection to the sows
- Typically extends through the roof
- Can also connect to a vent stack or another stack vent = vent header –> open air
Page 63
What is a Vent Stack?
Protects the base of a sows
How does a Vent stack protect the base of a sows?
Relieves positive pressures that are created when a slug of discharge travelling down the soil stack.
Where is the most effective connection of a Vent stack?
- Is at or immediately below the lowest vertical drainage connection to the soil stack.
- The above location has the highest pressure in the soil stack.
When is a Vent stack required?
When SOWS has fixtures draining into it from more than four storeys
Wet vent sows are exempt from this…
What is a Vent Header?
- Is the result of 2 or more vent stack or stack vent being joined together.
- Is Queen of the castle in the venting system
- Always leads to outside air
- Similar to stack vent, named differently in order to be sized by different rules
Stack vent + stack vent = vent header
Stack vent + Vent stack = Vent header
Vent stack + vent Stack = Vent header
