306A Drainage and Venting Systems

Question 1

What is the primary purpose of a vent system in a drainage installation?

Accepted Answer

To equalize air pressure in the drainage system and protect trap seals

Answer

To supply fresh air to the building interior

Answer

To increase the flow rate of waste water

Answer

To provide access for drain cleaning

Question 2

What is the minimum slope required for a 2-inch horizontal drainage pipe?

Accepted Answer

1 in 25

Answer

1 in 100

Answer

1 in 50

Answer

1 in 10

Question 3

What is the maximum number of fixture units permitted on a 2-inch vertical waste stack?

Accepted Answer

16

Answer

4

Answer

8

Answer

24

Question 4

What is a 'stack vent' in plumbing terminology?

Accepted Answer

The extension of a soil or waste stack above the highest horizontal branch connection

Answer

A separate vent pipe running alongside a soil stack

Answer

A vent connected at the base of a stack

Answer

A mechanical vent device installed on the roof

Question 5

What fitting is required when connecting a horizontal branch to a vertical soil stack?

Accepted Answer

Sanitary tee or wye fitting

Answer

Standard tee

Answer

Cross fitting

Answer

Reducer coupling

Question 6

What is the minimum diameter of a vent serving a 3-inch trap?

Accepted Answer

1½ inch

Answer

1¼ inch

Answer

2 inch

Answer

3 inch