Journeyman Plumbers Exam Drainage, Waste, and Vent Systems 2

Question 1

What is the minimum slope required for a 3-inch horizontal drain pipe under the IPC?

Accepted Answer

1/4 inch per foot

Answer

The IPC requires a minimum slope of 1/4 inch per foot for horizontal drain pipes 3 inches in diameter.

Question 2

A wet vent is permitted to serve which type of fixture combination?

Accepted Answer

Bathtub and lavatory on the same floor level

Answer

A wet vent typically serves a lavatory and bathtub/shower combination where the drain pipe also functions as the vent for the upstream fixture.

Question 3

What is the primary purpose of a P-trap in a drainage system?

Accepted Answer

To maintain a water seal that blocks sewer gases

Answer

A P-trap retains a water seal that prevents sewer gases and odors from entering the building through the fixture drain.

Question 4

Under the IPC, what is the maximum distance a trap can be located from its vent?

Accepted Answer

The distance depends on the pipe size and slope

Answer

The maximum trap-to-vent distance is determined by the pipe diameter — for example, 3.5 feet for a 1.25-inch pipe and 6 feet for a 2-inch pipe.

Question 5

Which fitting type is prohibited for use in a horizontal-to-horizontal drain change of direction?

Accepted Answer

Sanitary tee used on its side

Answer

A sanitary tee used in a horizontal plane (on its side) does not provide proper flow direction and is prohibited for horizontal drainage.

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