Journeyman Plumbers Drainage, Waste, and Venting Questions and Answers

Question 1

What is the primary purpose of a plumbing vent system in a drainage, waste, and vent (DWV) installation?

Accepted Answer

To equalize atmospheric pressure within the drainage system, protecting trap seals.

Answer

To provide a direct path for sewer gas to escape the building.

Answer

To increase the velocity of wastewater flowing through the pipes.

Answer

To serve as an overflow for the drainage system in case of a blockage.

Question 2

A plumber is installing a horizontal 3-inch drainage pipe. According to most model plumbing codes, what is the minimum required slope or grade for this pipe?

Accepted Answer

1/4 inch per foot

Answer

1/8 inch per foot

Answer

1/2 inch per foot

Answer

1 inch per foot

Question 3

Based on the Uniform Plumbing Code (UPC), what is the maximum allowable developed length of the trap arm for a 1 1/2-inch P-trap?

Accepted Answer

5 feet

Answer

3 feet, 6 inches

Answer

6 feet

Answer

8 feet

Question 4

A residential bathroom group consists of a standard toilet (3 DFU), a lavatory (1 DFU), and a bathtub with a shower (2 DFU). What is the total Drainage Fixture Unit (DFU) load that must be used to size the horizontal branch drain serving these fixtures?

Accepted Answer

The sum of the individual fixture DFU values

Answer

4 DFU

Answer

5 DFU

Answer

6 DFU

Question 5

Which of the following is a code requirement for the installation of cleanouts in a horizontal drainage system?

Accepted Answer

Cleanouts are required for each run of piping more than 100 feet in total developed length.

Answer

A cleanout is required every 50 feet on straight runs.

Answer

Cleanouts must be installed at each 45-degree change in direction.

Answer

The minimum size for any cleanout is 2 inches.

Question 6

A plumber needs to install a cleanout for a 4-inch horizontal drain pipe located in an accessible space. According to the International Plumbing Code (IPC), what is the minimum required clearance in front of the cleanout for rodding?

Accepted Answer

18 inches

Answer

12 inches

Answer

24 inches

Answer

36 inches