Quiz 3

Question 1

A sanitary drainage and vent system = drain, waste and vent (DWV) system:

Answer 1

A network of pipes that carries away sanitary wastes from within a building to a public sewer or to sewage disposal plant.

Question 2

A sanitary drainage and vent (DWV) system consists of

Answer 2

● Sanitary drainage side
● Vent system side

Question 3

Sanitary drainage side

Answer 3

Carries wastewater away from the plumbing fixtures and out of the building.
It consists of
● Traps at each fixture
● Fixture branches
● Stacks
● Building drains

Question 4

Vent system side

Answer 4

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

Question 5

Trap

Answer 5

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

Question 6

Q-traps (sometimes called ¾ S-traps) and S-traps

Answer 6

S-traps are generally not permitted
because they can easily be siphoned.

Question 7

Each trap must be

Answer 7

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.

Question 8

Fixture Branch

Answer 8

Drain line which connects horizontally the fixture to the sanitary drainage system.

Question 9

Branch slope

Answer 9

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

Question 10

Stack

Answer 10

Vertical pipe connected to the fixture branches.

Question 11

Soil Stack

Answer 11

Stack that carries human waste from water closet.

Question 12

Waste Stack

Answer 12

Stack that carries all waste except human waste

Question 13

Stack Info:

Answer 13

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.

Question 14

Pipe Chase

Answer 14

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.

Question 15

Building Drain

Answer 15

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.

Question 16

Building Sewer

Answer 16

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).

Question 17

Sanitary Sewer Main

Answer 17

Pipe through which the wastewater flows to the wastewater treatment plant.

Question 18

Cleanouts

Answer 18

Screw-type fittings with a cap that can unscrew to allow access to the inside of the sanitary drain pipes.

Question 19

Cleanouts are generally required:

Answer 19

● 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.

Question 20

Vents

Answer 20

Pipes that introduce sufficient air into the drainage system.

Question 21

Reasons of venting

Answer 21

● 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.

Question 22

Types of venting methods:

Answer 22

1. Individual vents
2. Common vents
3. Wet vents
4. Circuit vents
5. Combination drain and vent

Question 23

Individual venting

Answer 23

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.

Question 24

Common venting

Answer 24

Individual vent that serves no more than two traps or trapped fixtures located on the same floor.

Question 25

Wet venting

Answer 25

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.

Question 26

Circuit venting

Answer 26

Horizontal venting pipe serving up to eight fixtures.
Each fixture must be connected to a single horizontal drain.

Question 27

Combination drain and vent system

Answer 27

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.

Question 28

Vent Stack

Answer 28

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.

Question 29

Sewer ejection

Answer 29

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.

Question 30

The value of DFU for a particular fixture depends on

Answer 30

● The rate of drainage discharge
● The duration of a single operation
● The frequency of operation