Quiz 3 Flashcards
A sanitary drainage and vent system = drain, waste and vent (DWV) system:
A network of pipes that carries away sanitary wastes from within a building to a public sewer or to sewage disposal plant.
A sanitary drainage and vent (DWV) system consists of
● Sanitary drainage side
● Vent system side
Sanitary drainage side
Carries wastewater away from the plumbing fixtures and out of the building.
It consists of
● Traps at each fixture
● Fixture branches
● Stacks
● Building drains
Vent system side
Introduces and circulate air in the system to
● Maintain atmospheric pressure in the drain lines
● Ensure adequate gravity flow of wastewater
● Prevent a negative pressure (suction) in the system that could suck water from fixture traps and allow sewer gases to infiltrate the building
● Exhaust sewer gases to the outdoors
Trap
A portion of piping in U shape and filled with a water seal.
The water column in a trap is between 2 – 4 in. deep.
Prevents the backup of sewer gas into a building through the drainage connection of plumbing fixtures.
Water closets, Bidets, Urinals have an integral trap:
Other plumbing fixtures use external traps:
Traps are made of
copper
plastic
steel
wrought iron
brass
Q-traps (sometimes called ¾ S-traps) and S-traps
S-traps are generally not permitted
because they can easily be siphoned.
Each trap must be
Each trap must be vented to the atmosphere.
Reason:
To prevent the liquid seal being sucked dry if a pressure differential is created between the building and the sewer.
Fixture Branch
Drain line which connects horizontally the fixture to the sanitary drainage system.
Branch slope
1/8 to ½ in. per ft (10.4 to 41.6 mm per meter) beginning from the fixture.
Branch piping material: copper, approved plastic, galvanized steel, cast iron
Branch piping location: under the floor
Stack
Vertical pipe connected to the fixture branches.
Soil Stack
Stack that carries human waste from water closet.
Waste Stack
Stack that carries all waste except human waste
Stack Info:
Stack material: copper, approved plastic, galvanized steel, cast iron
Stacks are connected to the building drain and fixture branches.
The connections should be angled 45* or more to allow smooth flow of wastewater.
A stack must be supported at 10-ft (3 m) intervals to limit movement of the pipe.
Pipe Chase
Space that is left to put the pipes in, it runs from the first floor to the roof of the building.
A drain stack connected to an underfloor building drain.
There is a floor cleanout at the base of the stack.
Building Drain
Horizontal pipe from the drain stack to building sewer. It extends 2 to 5 ft (0.6 to 1.5 m) outside the foundation wall of the building.
Building drain slope: 1/16 to ½ in. per ft (5.2 to 41.6 mm/m)
1/8 to ¼ in. per ft (10.4 to 20.8 mm/m) are common in most buildings.
Building Sewer
Extension of the building drain that carries wastewater from the building drain to a community sanitary sewer main.
Building sewer slope: 1/16 to ½ in. per ft (5.2 to 41.6 mm/m).
Sanitary Sewer Main
Pipe through which the wastewater flows to the wastewater treatment plant.
Cleanouts
Screw-type fittings with a cap that can unscrew to allow access to the inside of the sanitary drain pipes.
Cleanouts are generally required:
● At the base of soil and waste stacks.
● At the upper end of building drains.
● At changes in direction where the cumulative bend exceeds 120o.
● No more than 50 ft (15 m) apart in the long building drains.
● At the junction between the building drain and building sewer.
Vents
Pipes that introduce sufficient air into the drainage system.
Reasons of venting
● To protect the trap seal
● To reduce air turbulence from siphoning or back pressure
● To release sewer gases to the outside
If traps do not exist in a drainage system, venting could be eliminated.
Types of venting methods:
- Individual vents
- Common vents
- Wet vents
- Circuit vents
- Combination drain and vent
Individual venting
Installation of a vent pipe for every trap or trapped fixture.
It is the easiest method to ensure the preservation of a trap seal.
It is the most costly method because it requires many vent pipes in the system.
The way to reduce the cost of venting is to combine vents into the system.
Common venting
Individual vent that serves no more than two traps or trapped fixtures located on the same floor.
Wet venting
Single vent pipe to provide venting for all of the fixtures of one or two bathroom groups located on the same floor.
The vent pipe for the lavatory typically serves as the vent for the other
fixtures in the bathroom.
Circuit venting
Horizontal venting pipe serving up to eight fixtures.
Each fixture must be connected to a single horizontal drain.
Combination drain and vent system
In this system there is a distance from trap to vent and this distance can be extended infinitely.
Codes limit the distance between the trap and the vent.
The drain is in the horizontal direction.
The vent is in the horizontal branch.
Vent Stack
Extends vertically through the building and up through the roof to the
exterior of the building.
It must extend beyond the roof at least 6 in. and terminate to open air.
The vent stack can also begin at the soil or waste pipe, just below the lowest
horizontal connection, and may go through the roof or connect back into the soil or waste pipe not less than 6 in. above the top of the highest fixture.
Sewer ejection
Pumping system to lift wastewater to the level of the main drain or sewer.
It is used in buildings where a fixture or a group of fixtures are installed below the level of the nearest available sewer line.
A sewer ejector can pump solids from 2 to 4 in. in size or grinds solid wastes before passing them through the ejector.
The value of DFU for a particular fixture depends on
● The rate of drainage discharge
● The duration of a single operation
● The frequency of operation
