Master Plumber Exam Drain, Waste, & Vent Systems 2

Question 1

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

Accepted Answer

1/4 inch per foot

Answer

The IPC requires horizontal drain pipes 3 inches and smaller to slope at a minimum of 1/4 inch per foot toward the point of discharge.

Question 2

A wet vent serves which dual function in a DWV system?

Accepted Answer

It carries both wastewater and acts as a vent for another fixture

Answer

A wet vent simultaneously carries wastewater from one fixture while serving as the vent pipe for another fixture on the same branch.

Question 3

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

Accepted Answer

6 feet

Answer

The IPC limits the distance between a P-trap and its vent to a maximum of 6 feet for a 1.5-inch trap arm.

Question 4

Which type of vent connects the vent stack to the soil or waste stack at a point above the highest fixture's flood-level rim?

Accepted Answer

Stack vent

Answer

A stack vent is the extension of the soil or waste stack above the highest horizontal drain connection, terminating outdoors as the vent termination.

Question 5

What is the primary purpose of a cleanout installed in a horizontal drain line?

Accepted Answer

To allow inspection and clearing of obstructions without removing piping

Answer

Cleanouts provide access to drain lines for rodding and jetting to clear blockages without dismantling the pipe system.

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