306A Drainage and Venting Systems 2

Question 1

What is the difference between a soil stack and a waste stack?

Accepted Answer

A soil stack carries water closet discharge; a waste stack does not

Answer

Soil stacks are underground; waste stacks are above ground

Answer

Soil stacks are vertical; waste stacks are horizontal

Answer

There is no difference

Question 2

What is the purpose of a circuit vent in a multi-fixture drainage system?

Accepted Answer

To serve as a single vent connection for a group of fixtures on a horizontal branch

Answer

To vent each fixture individually

Answer

To replace the main vent stack

Answer

To connect the drainage system to the building sewer

Question 3

What is the maximum distance that a vent can run horizontally below the flood level rim of the fixture it serves?

Accepted Answer

No horizontal vent is permitted below the flood level rim

Answer

150 mm maximum

Answer

300 mm maximum

Answer

Any distance if properly graded

Question 4

What is an 'island vent' (loop vent) used for?

Accepted Answer

Venting a kitchen sink in an island counter where a traditional vent cannot rise directly to the roof

Answer

Venting fixtures on a rooftop

Answer

Venting outdoor plumbing fixtures

Answer

Replacing the main vent stack

Question 5

What must be done if a vent pipe is exposed to freezing conditions where it terminates through the roof?

Accepted Answer

Increase the vent size by at least one pipe diameter before it passes through the roof

Answer

Insulate the pipe only

Answer

Install a heat trace cable

Answer

No special treatment is required

Question 6

What is the purpose of a fresh air inlet (fresh air vent) in a building drainage system?

Accepted Answer

To introduce fresh air into the drainage system near the building trap to promote air circulation

Answer

To provide combustion air for gas appliances

Answer

To exhaust sewer gases above the roof

Answer

To supply ventilation to the basement