Master Plumber Exam Drain, Waste, & Vent Systems 4

Question 1

Under the IPC, what is the minimum height above the roof surface for a vent pipe termination in a climate where frost closure is not a concern?

Accepted Answer

12 inches

Answer

Vent pipe terminations must extend at least 6 inches above the roof surface, or 12 inches if within 10 feet of a roof-mounted equipment intake.

Question 2

Which condition most commonly causes a trap seal to be lost by evaporation rather than siphoning or back pressure?

Accepted Answer

A fixture that is seldom used for extended periods

Answer

Infrequently used fixtures allow water in the trap to evaporate over time, breaking the seal and allowing sewer gases to enter the building.

Question 3

What is the function of a revent (individual vent or back vent) in a DWV system?

Accepted Answer

It provides a separate vent connection from a trap back to the vent stack to prevent siphonage

Answer

A revent connects the trap arm or drain of a fixture to the vent stack, providing a dedicated air path to prevent trap siphonage caused by negative pressure.

Question 4

According to the IPC, at what interval must cleanouts be installed in a horizontal drain run?

Accepted Answer

Every 100 feet

Answer

The IPC requires cleanouts to be installed every 100 feet on horizontal drain piping to ensure the entire run can be accessed for clearing.

Question 5

A double sanitary tee (double tee-wye) fitting is used when connecting back-to-back fixtures to permit flow in which directions simultaneously?

Accepted Answer

From both sides into a common vertical drop

Answer

A double sanitary tee allows simultaneous waste discharge from fixtures on both sides of a wall into a shared vertical drain, each entering the tee from opposite sides.

Master Plumber Exam Practice Test

Master Plumber Exam Practice Test

Master Plumber Exam Drain, Waste, & Vent Systems 4