Journeyman Plumbers Exam Drainage, Waste, and Vent Systems 5

Question 1

Under the IPC, what is the maximum number of fixture units permitted on a 3-inch horizontal branch drain sloped at 1/4 inch per foot?

Accepted Answer

20 DFUs

Answer

A 3-inch horizontal branch at 1/4-inch-per-foot slope can carry a maximum of 20 drainage fixture units per IPC Table 710.1(2).

Question 2

Which of the following best describes back-pressure (positive pressure) in a drainage stack?

Accepted Answer

Pressure that builds below a slug of falling water and can push trap seals into the room

Answer

As a slug of water falls down a tall stack, it compresses air below it, creating positive pressure that can force trap seals out of lower-floor fixture traps.

Question 3

A floor drain trap primer is used to:

Accepted Answer

Periodically supply water to a floor drain trap to prevent the seal from evaporating

Answer

Trap primers supply small amounts of water to infrequently used floor drain traps to replace water lost to evaporation and maintain the sewer gas seal.

Question 4

What material is NOT permitted for use as a DWV pipe under the IPC in a concealed location?

Accepted Answer

Galvanized steel threaded pipe

Answer

Galvanized steel threaded pipe is not listed for DWV use under the IPC; approved materials include cast iron, ABS, PVC, and copper drainage tube.

Question 5

A combination waste and vent system is typically used for:

Accepted Answer

Floor drains and sinks in slab-on-grade commercial kitchens where conventional venting is impractical

Answer

Combination waste and vent systems use oversized horizontal drain pipes as both the drain and vent, and are commonly applied to floor drains in slab construction where vertical venting is difficult.

Journeyman Plumbers Exam Practice Test

Journeyman Plumbers Exam Practice Test

Journeyman Plumbers Exam Drainage, Waste, and Vent Systems 5