Journeyman Plumbers Exam Drainage, Waste, and Venting 2

Question 1

What is the minimum slope required for a 3-inch horizontal drain pipe per the Uniform Plumbing Code?

Accepted Answer

1/4 inch per foot

Answer

The UPC requires 1/4 inch per foot (2% grade) slope for horizontal drain pipes 3 inches and larger.

Question 2

A wet vent is permitted to serve which combination of fixtures?

Accepted Answer

Bathtub and lavatory on the same floor level

Answer

A wet vent commonly serves a bathtub and lavatory located on the same floor, where the drain also acts as the vent.

Question 3

When installing a drum trap, where must the outlet be located relative to the inlet?

Accepted Answer

At least 2 inches above the inlet

Answer

The outlet of a drum trap must be located at least 2 inches above the inlet to maintain the water seal.

Question 4

Which type of vent is installed on the downstream side of a fixture trap to prevent siphoning?

Accepted Answer

Back vent (individual vent)

Answer

A back vent, also called an individual vent, connects to the fixture drain on the downstream side of the trap to prevent trap siphoning.

Question 5

What is the maximum developed length of a 1.5-inch trap arm from trap weir to vent?

Accepted Answer

42 inches

Answer

Per the UPC, a 1.5-inch trap arm has a maximum developed length of 42 inches (3.5 feet) from the trap weir to the vent.

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