306A Drainage and Venting Systems 3

Question 1

What is a 'combination waste and vent' system?

Accepted Answer

A system where oversized horizontal waste pipes serve as both drain and vent for floor drains and similar fixtures

Answer

A system where all pipes serve both functions simultaneously

Answer

A system that uses mechanical vents exclusively

Answer

A system with no vent connections at all

Question 2

When connecting two drainage pipes at a junction, why is a wye and 45-degree bend preferred over a tee?

Accepted Answer

It provides a smoother flow transition and reduces turbulence

Answer

It is cheaper to install

Answer

It takes up less space

Answer

It is easier to solder

Question 3

What is the maximum offset angle permitted in a soil or waste stack without special venting?

Accepted Answer

45 degrees

Answer

22.5 degrees

Answer

60 degrees

Answer

90 degrees

Question 4

Why must a vent pipe always rise above the fixture flood level rim before connecting horizontally to the vent stack?

Accepted Answer

To prevent waste water from flowing into the vent during a fixture backup

Answer

To reduce pipe material costs

Answer

To make installation easier

Answer

To improve aesthetics

Question 5

What is the minimum grade required for a vent pipe that runs horizontally?

Accepted Answer

1 in 100 back toward the drainage pipe it serves

Answer

No grade is required

Answer

1 in 50 toward the drainage pipe

Answer

1 in 25 toward the drainage pipe

Question 6

What is the minimum distance a vent terminal must be from any openable window, door, or air intake?

Accepted Answer

900 mm

Answer

300 mm

Answer

600 mm

Answer

3 m